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In need of some desperate advice. Glass Aq. reseal doubts 6/7/11
I hope someone can give me some advice. I have perused so many websites looking for answers to my questions and came across this site and have been reading every query on this site for the last couple days.
I'm sure I know the answer you are going to give me, but I guess I'm hoping that you may alieve my concerns. Problem is; I purchased a used 90 gal. tank/canopy/stand
off of craigslist a week ago. The tank was being used just prior to my purchasing (or so he says!) After getting it home and checking it out thoroughly, I noticed all the seals were lifting on the edges and were stained green.
<Likely this tank was treated w/ a medication including Malachite Green...>
I found it to be unattractive and decided I would reseal the tank myself. Having never done this before, and not really knowing how to go about doing it, I checked out a couple websites on how-to's (regrettably not this one) and watched a video clip on how to do this. The guy on the video made it look so easy....looked like he was slicing bread when he cut the old silicone out!
<Is easy... well easier, given tools, experience>
He did not emphasize thoroughly scraping/cleaning off any residue left on the glass nor did he say anything about being careful not to cut any silicone in between the glass pieces.
Well guess what??? I don't think I may have scraped/cleaned all the residue off before resealing (which was much more difficult than I thought!) although I did wipe all the seams w/alcohol.
<Not generally useful, "strong" enough. Other organic solvents are suggested>
Also, on one of the sides, As I brought the blade down on the side glass & cut away the silicone I realized that there was about an 1/16"-1/8" gap between the bottom & side glass almost the whole length of the side, which was filled with silicone (that I accidently cut into, although I don't believe I sliced all the way through it-just scraped off the top layer!) Didn't think there was supposed to be a gap this size-but obviously it had been holding like this for the 8 yrs. the previous had it set up???
<Could be; though, as you state, 1/8" is a big gap>
Also, on the front panel...same thing, there is one area on the seam approx. 3/4" long that the bottom glass was chipped off leaving a small gap there too! After resealing the whole tank and letting it sit for about 8 hrs. I realized I missed sealing approx an inch on the bottom on one side near the corner. My LFS guy told me to cut that side out but leave the corners sealed still and reseal the side again. After reading many times on this site that old/new silicone do not adhere I am worried that I will get a leak where the two meet.
<Not likely so, no>
I did go all the way across and over the silicone in the corners again...do you think that will help?
<Mmm, yes. The "actual" seal is the small bit of Silastic squeezed twixt the panes, not the corner bead, which mainly functions to protect the real seal from overzealous algae scraping/scrapers>
LFS guy says that 8 hours was not long enough for it to cure completely and should adhere.
<Mmm, no... this material "skins" in about an hour>
So with this advice, I decided to go over the one side with the gap & the front piece w/a small gap with the silicone again as an added protection. What do you think?
<Same as above. Not likely a big deal in any case>
I have the tank outside on the patio currently, and has been 3 days since putting on last coat of silicone. I am so afraid that the tank will burst when I fill it!
<Don't be... test fill outside on the stand, making sure the support underneath is planar and level; leave like this for a few days. No sense living our lives in fear>
Would it be best to just put in a couple inches of water first to see if it's going to leak and wait a day or two before filling all the way or should I just go for the full Monty and filler up?
<You could... but I'd place some sheets of newspaper (to detect water) and fill to the top>
Really can't afford a new tank and really want to save this tank if possible. Any suggestions would be greatly appreciated.
<Welcome. Bob Fenner>
re: In need of some desperate advice, Glass Aq. seal job 6/8/11

Hi Bob,
Thank you for writing back so soon and thank you for your advice! This morning (I got impatient) I thought I would just go for it. One way or another I needed to find out if it was going to leak/burst or not. So I leveled it sitting on the concrete patio not on the stand
(or so I thought) and filled it all the way up. Unfortunately, after filling, I discovered it wasn't as level as I thought.
<Very bad!>
The side that is in question (with the gap) sits about 3/8" lower than the other side but the front to back is pretty level (Guess my patio isn't as level as I thought)
<None are. Drain this tank immediately (if not sooner) and place as was suggested to you previously>
Well it has been about 9 hours now and so far so good....NO leaks!! Is this a good sign or is there still a chance that after another day or two it could still spring a leak/break from being this un-level?
<May break in its present placement period>
Should I empty-relevel and fill again?
<Read here: http://wetwebmedia.com/aqstands.htm and the linked files above>
My next question to you is; although I don't see any bubbles in the new seal I put down (well maybe just one little one about 1/8" but does not go into the seam) I do see many, many microscopic bubbles in the seal between the panes on all four corners the whole length of the seam and some seem to have connected and formed a little larger bubble. Is this normal?
<Read here: http://wetwebmedia.com/glstksilasticf2.htm
I checked my other tank (purchased new a few months ago) and it also has these microscopic bubbles although no where near as many as this tank, I'm assuming this is common?? Is there still a chance that this tank will hold while set up outside but after emptying and bringing in the house and filling up that it could still leak/burst or is it safe to assume if it held outside it will hold inside? Was hoping to empty & bring in on Friday, is 3 days long enough to wait and see if it's going to leak? I will definitely make sure it is sitting perfectly level on the stand when I do bring it in! Thank you so much for all your expert advice, you definitely have a new follower and I will be checking out your web for any new ideas or suggestions to others on a frequent basis. Have a great night!
<Keep reading. BobF>

My Reseal Job 6/4/2011
<13 plus megs of images...>
I recently purchased a used 90 gallon tank, and I didn't like the look of the seals so I resealed them. I actually did the process a couple of times because I am a perfectionist and I wanted it done right. Every time that I reseal it there are air bubbles in the silicone and I am paranoid that this could be a problem in the future. They are not in the main bracing just between the bracing and the silicone on the inside, but it happens every time. Here are some pictures of it, could you tell me if it will be ok?
<S/b fine. Bob Fenner>

Re: My Reseal Job 6/4/2011
Thank you for the lightning response.
<Gots to respond quick to delete your massive file, make space for incoming... But welcome. I have used MANY cartridges of Silastic, making, repairing glass aquariums, sumps and such... some are quite "bubbly"... the sealant in the corners (as opposed to the actual joints themselves) functions mainly to prevent sharp tools getting into the joints. Cheers, BobF>

Poisoning from silicone sealant 4/10/11
Maybe somebody in the crew has had experience with this. I had purchased a used aquarium that had apparently been resealed with silicone that is not of aquarium-grade. (Same situation Neale addressed a week or two ago.) I have since replaced the tank with a brand new one (also bought new substrate), and I kept the affected fish inside a breeder net in a known good tank for several days.
Most of the fish recovered quite a bit. Friday I began moving them into the new 10-gallon tank, but they still seem to be impacted by the same kind of poisoning, only slower, indicating a lower concentration. I wonder if the anti-mildew chemicals might have seeped into the plastic of the box filter, thermometer base, heater end caps, and perhaps the plants and are now leeching back into the water?
<No. Just the non-aquarium Silicone>
Last night I did an emergency 90% water change and replaced the box filter with a brand new still in the box, as well as replacing the silicone air tubing and adding a filter bag with activated carbon above the box filter.
The shimmying and fin clamping symptoms seem a little better this morning, but I think I need to continue to do water changes at least daily for a while. If anyone has dealt with this issue before, I'd appreciate some insight on how long it might take to purge the chemical down to a negligible concentration.
(Sigh. I lose way too many fish due to things other people have done.)
<Can indeed be toxic. See WWM re. B>
Re: Poisoning from silicone sealant 4/10/11
Hi Bob, it's been a while since I heard from you. Nice article in TFH this month, and I also found a copy of your book and am reading. Excellent, but needs a freshwater companion volume! ;)
<I do wish the times (economically) were more propitious. It would be greatly enjoyable to produce such a work>
As I said, the inappropriate silicone is long gone but the effects seem to be lingering, which is why I think it may have at minimum adsorbed onto some plastic/rubber surfaces. Maybe I'm already at a low PPM but some of the fish probably still weak from the previous tank. (Bought used, as I said, not repaired by me--I know better.)
<Do run some (a few ounces) of good quality activated carbon in you filter or flow path. BobF>

Using Silicone Within A 'Live' System -- 02/25/11
Dear Crew,
<<Hiya Joe>>
Is it safe to use aquarium-grade silicone sealant in a temporarily dry part of an established system,
or are there considerable risks, due to spillage/seepage?
<<Considerable'¦nah. Just be sure to let the silicone cure completely before getting it wet'¦and this mainly so you don't spoil the repair versus any big dangers to the system re>>
The work in question would be at the top of the weir, to replace old combing with new. I will drop the water level a few inches, but will be working quite close to it.
<<This is not a problem>>
Apart from taping freezer bags to protect the rocks near the weir, and working slowly and carefully, is there anything else I can do/should be aware of in attempting this?
<<Sounds like you have it under control>>
All the best.
<<Cheers'¦ EricR>>

Resealing a 55 gallon tank 1/30/11
Hi crew,
I received a used 55 gallon about a year ago that has no bottom center brace
and just the plastic one at the rim..
<Ah! This is "par for the course". Typically 55's only have a top brace>
It was placed on a cast iron stand that also had no center brace. I didn't think anything of it until I redecorated the tank and moved some rocks into the center. Three hours later, it began streaming water from the sides. The water leak stopped when the water level was brought down to about 1/2.
After putting green terrors into the turtle tank (everyone's fine!), we (okay, my fiancée) started following the suggestions at
The inside silicone got scraped away and cleaned off, at which point she noticed two things:
1) An almost semicircular chip on the interior face of one of the small panes of glass. It starts at 2 5/8" down and ends at 3" from the top. The radius at its longest point is 3/8", starting at the edge of the glass and extended towards the middle of the pane. She hypothesizes that it was totally covered by the previous sealant. It is above the place where the water started leaking by at least a foot.
<Mmm, maybe>
2) On that same corner, if she applies force near the corner, the small pane of glass moves slightly.
<What?! Very dangerous!>
We haven't resealed it yet because we're worried about these two problems.
I'm debating a planted tank, which can be heavier, if more equally distributed, than what I did before. You've mentioned that 55 gallons are "competitively priced". Are these fixable issues that aren't likely to make
problems later? I'd hate to drain the tank onto the floor.
<Mmm, I'd be shopping about... depending on what you consider "your time is worth", a tank of 48 L by 13 W nominal inches and whatever height may well be better to buy than try re-sealing this one... Which I would reseal and use partially filled... for a paludarium, vivarium, perhaps an aquatic turtle system>
Many thanks for your awesome site,
<Welcome! Bob Fenner>

Silicon<e> and dying fish??? 12/28/10
I was reading about artificial plants on the net. There is this site that describes using silicone as a base for fake plants. My husband went and used GE silicone II as a plant base and put the plant in. The tube said
that the stuff was not "aquarium safe" My husband then said that meant it wasn't safe to seal an aquarium with and the manufacturer does not want a lawsuit if a huge tank explodes from the wrong silicone.
Anyway, the plant was in there all night and the fish were acting weird this morning. One was hanging out under the filter, the other two were acting normal. I checked on line and found out that this silicone is toxic
to fish, so I removed the plant and did about a 90% water change and replaced the salt. The three mollies are just hanging out now, but that may be the stress from the huge water change. Anyway would Epsom salts help or do I just wait to see if it is too late. I will no longer let my spouse
make any aquarium decisions again. Thank you!!!
<Greetings. Yes, it is true that you need to use only aquarium-safe silicone around fish. The silicone itself isn't toxic so far as I know, but the anti-fungus chemicals added to the silicone usually are toxic, and the
aquarium-safe silicone lacks these. Removing the silicone from the tank, and then doing one or more large water changes, should bring things back down to normal. The addition of fresh carbon to the filter would also be very helpful. After a week, remove that carbon and throw it away. Cheers, Neale.>
<<RMF would like to try correcting misstatements I have made re the use of various "Silicone" formulations... They are NOT necessarily toxic, but often unsuitable in other ways. Please see the discussion here: http://www.gtaaquaria.com/forum/showthread.php?p=107998
Mea culpa, but I have misunderstood that 100% Silicone on labels was and is NOT the same product/formulation. ONLY ones distinctly labeled FOR AQUARIUM USE should be employed for such>>
Re: Silicon and dying fish??? 12/29/10

I was e-mailing yesterday about a fake plant with a silicon base, that was toxic to fish. I mentioned I removed the plant and did two water changes yesterday that replaced about 90% of the water each time. Two of the three mollies are back to normal this morning, but one is at the bottom and will not come to the top even for food. She is just there. The other two mollies are adult size. I got this smaller molly in a tank with a group of adults and the guy at the store said she is either a baby or a runt. Anyway it doesn't look like she will make it. My question is: Is the fish suffering??
In that case is it better to put it too sleep or should I wait until she passes on her own??? Thank you!!
<Only you can tell if the fish is suffering. But yes, if she's doomed, there's no point waiting. Do read here:
The ice method mentioned in old aquarium books isn't humane, but the clove oil method is, and 30 drops in a litre of aquarium water quickly sedates and then kills suffering fish. I highly recommend this method because it's safe, cheap and reliable. Drug stores sell clove oil, sometimes as Eugenol.
Cheers, Neale.>

20 year old fish tank `12/27/10
You guys are really great! I couldn't find an answer on previous posts, so I hope I'm not wasting your time with my question. I recently bought from Craigslist a 150 gallon tank (72" long) which was never used, but is 20 years old. The silicone does not seem to have yellowed (I have some experience in fish tanks and handy work), and is still soft to the touch.
Besides for that, I bought it to upgrade from my 75, but having no room in my house for it, it's sitting on my back porch covered, but in freezing temperatures (NJ) until I build a new stand for it. Do you think it will be a problem? Do I need to replace the silicone?
<Mmm, I'd take a/the small risk of this tank having some issue with the old/er Silastic/Silicone here. I know of many such sized glass thanks of this and older age that are fine>
If I can one more question, it has a chip on the long glass (like a rock hitting a windshield) less than 3mm wide, and a little more than a finger nail deep. From reading previous questions the answers are mostly for
chipped corners, but couldn't seem to find one real similar to mine. I filled the tank for about 24 hours to test it, but I don't know for sure when the chip got there. Before or after the water fill.
<I'd re-test, refill it to check>
I'm pretty sure before, and I just didn't notice it. Should I worry?
<Not likely, no>
Thanks so much!! Your answers are real helpful, and sometimes lifesavers (for the fish of course)!!!! Keep up the great work.
<Thank you for your positive comments, input. Bob Fenner>
Re: 20 year old fish tank `12/27/10
Thanks so much for the fast reply! Just to be clear on the first part, the fact that the tank is outside in freezing weather (plus snow) is not a problem? Thank you so much again for your time!! Eric
<Not a problem with the cold weather. Silicones, once "cured" are fine to very gold temperatures. Think on their "other" main application: Holding glass windows in place in buildings... at times in very cold settings.
Cheers, Bob Fenner>

Need asap help with joint structural seam on used tank! 9/16/11
I just bought a 3 years old 175 gallon oceanic Bowfront from the LFS. The silicone was worn in one of the corners, so I decided to re-seal it. I cleaned it off really well and applied the new all-glass clear silicone and the next morning, I noticed the black silicone that holds the joint between the front to the side pane has small air lines. Is this something to be concern about?
<Mmm, no; not really. Those shown in your excellent images are small, inconsequential functionally>
I am hoping I do not have to remove the joint silicone, that would be more work. After having to redo the seams 3 times due to my lack of experience hence sloppy silicone, the air gaps in the joints grew a small amount approx .3mm. Or it could be the fact the tank hasn't been filled for 2 months since it was filled for 3 straight years.
But...based on a quick evaluation, there appears to be enough support to keep the glass in tact given these facts:
1.) The trim from oceanic is built like a solid
2.) The weight of the front glass is heavy
3.) The inner joints are thick and RTV 103 (Adhesive silicone) is used I couldn't see how a few small air gaps in the seam structural joints could cause this tank to fail.
Can anyone chime in on this? thoughts?
Pics are attached.
<Not a worry; you can see some similar examples to real trouble posted on WWM. Bob Fenner>

Re: Need asap help with joint structural seam on used tank! 9/16/11
Ok last questions,
I already removed one corner (vertical) seam, and attempting to reseal. How thick should the seams be and do I have to redo all the seams because I removed 1 seam?
<Depends on your purpose/s. Read here: http://wetwebmedia.com/glstksilastic.htm
and as much of the linked files above as you'd like/need. BobF>
Re: Need asap help with joint structural seam on used tank! 9/16/11

What do you mean purpose? I want my tank to hold water and not leak.
<... Heeeee!>
I don't want to redo all the seams inside the tank just because I removed a vertical seam. The tank wasn't leaking, the seam was just worn.
<Then don't reseal>
I read the link but I got conflicting info.
<Not to worry. B>
For a 175 gallon Bowfront using RTV adhesive silicone, how wide should the seam/beads be?
<... these are not functional... keep reading>
Also, will I have to replace all the silicone inside because I stripped one corner off?
Please help.
Re: Need asap help with joint structural seam on used tank! 9/17/11

Ok this is great news! So I should be ok without redoing all interior because I scraped off the one corner seam? (Not the Joint seam as original suggested)
<I would not be doing/re-doing all>
I have been stressing. This is Bob correct?
<Yes; no to low stressing. ;), B>

Re: Need asap help with joint structural seam on used tank! 9/23/11
Hello Bob it's me again. A few final questions...sorry for the paranoid emails but I had a 90 gallon bust on me 2 yrs ago causing a lot of damage so I wanted to take extra pre-caution before taking next steps.
<No worries>
So I have redone the seams to one corner of the tank w/ Momentive Adhesive RTV-103 silicone. This is very popular silicone among aquarist to build tanks and supposingly the strongest based on my research.
I only redone that one seam because the rest looked great condition.
I have let the silicone cure for 5 full days and no smell is present.
I know old silicone does not adhere to new silicone.
<Not much, no>
The tank is
presently in water leaking phase and has survived 12 hours so far.
The 175 gal Bowfront tank was purchased used and is only 3 years old made by oceanic.
<A good maker IMO>
My questions are:
1.) The new corner silicone connects on and right over the old bottom silicone sticking to the glass. So I believe this would over rule having to re-do all the inner seams since new silicone is placed right on the glass above the old bottom seam. (Especially the RTV is 40lbs tensile strength psf)
2.) Would it make sense to see if it survives 24-48 hour water leak test and empty and let the silicone cure more?
<No need... is fully cured in 24 hours>
Is 5 days long enough for RTV 103 to cure?
3.) When can I say its fully safe and start stocking the tank?
Hopefully the new seams are strong. By the touch and look of it, it sure feels it.
<When the system is cycled... but ready to set-up now>
4.) How does new adhesive silicone stick to old sealant silicone.
<In terms of physics?>
5.) Does it make sense to seal the outside corners just incase?
<No... or only where there are chipped areas, to prevent possible snagging of clothing, cutting of fingers, hands>
Opinions and advice are needed! Thanks again for reading and alllll your help!
<Certainly welcome. Bob Fenner>

Re Joint Structural Silicone Seam inspection (URGENT) 9/27/11
Hello Bob!
Thanks again for all your help. You are a life saver, especially during times such as these...I have finally filled my tank upon your approval saying that the silicone seams are good to go. Its been 5 days now and the tank is still holding water. But for some reason, I just needed further assistance with the silicone seams again given that it's been submerged in water and hopefully the new pics can tell the story on its condition.
Do you know if its okay to completely set up this tank now with substrate etc.,?
<Yes; should be fine to do so>
I have attached pics.
Pics guide:
1 top.jpg is a pic of the higher end of the joint seam
2 lower.jpg is lower end of the joint seam
Inside 2.jpg is on the inside of the tank
Inside.jpg is another shot of the inside work
tank.jpg is the tank
two weeks ago.jpg is the old silicone using the AGA silicone and same spot as the 1 top.jpg
Thanks again Bob! You're the best!!!
<Welcome! BobF>

Scott, your too-large image files are taking more than ten minutes to download here in Fiji... Have deleted to make room in our too-small mail server... Please resize to the guideline standard of a few hundred Kbytes and re-send all. Bob Fenner
Subject: Sealing of my tank 9/4/11
I recently bought a used tank and saw something that concerned me. The sealant used on the glass is black and one corner of the tank the black appears to have faded away. I just would like someone with experience (namely you :) ) to confirm that this isn't a problem. I've attached two pictures of the area where the black is faded and another corner of the tank for contrast.
On a side note, I've got some Liverock from my last system that I'm looking
to sell. For whatever reason I couldn't keep snails alive in that tank. I was worried the previous owner used copper in the tank, but there are feather dusters growing all over the Liverock and no copper could be detected in the water column using a test. Do those facts eliminate the possibility of copper being in the tank or copper infecting the Liverock--I just want to make sure I don't sell someone Liverock with copper!
Thank you,
Re: Sealing of my tank 9/4/11

Sorry about that.
Please find the attached resized pictures.
<Ah, thanks>
Also, I have a third question: is there any chance that pure white distilled vinegar could erode the silicone seams?
<Dilute acetic acid? Nah, not much>
I'm using it to clean off stubborn algae and just concerned that not diluting the vinegar with water could affect the seams.
<Again...>> Hi,
> I recently bought a used tank and saw something that concerned me. The sealant used on the glass is black and one corner of the tank the black appears to have faded away. I just would like someone with experience (namely you :) ) to confirm that this isn't a problem. I've attached two pictures of the area where the black is faded and another corner of the tank for contrast.
<The orange area... biota is a worry>
> On a side note, I've got some Liverock from my last system that I'm looking to sell. For whatever reason I couldn't keep snails alive in that tank.
I was worried the previous owner used copper in the tank, but there are feather dusters growing all over the Liverock and no copper could be detected in the water column using a test. Do those facts eliminate the possibility of copper being in the tank or copper infecting the Liverock--I just want to make sure I don't sell someone Liverock with copper!
<Not likely at all a problem>
> Thank you,
> Paul
<Welcome. Bob Fenner>

Re: Sealing of my tank 9/5/11
Thank you so much for your advice. How much of the orange area is a problem?
<All of it if it expands, extends into the "real" seal... which is the joint twixt the glass>
Should I just scrap the tank?
<Mmm, I wouldn't, no... this part or run of sealant can be easily removed, replaced. Read here: http://wetwebmedia.com/glstksilasticf2.htm
and the linked files above>
I was going to fill it today, but now I'm pretty scared.
<Mmm, well, you could fill, add some chlorine bleach, perhaps "kill" off the orange area... >
Would more pictures help?
<Nope. BobF>

Re: Sealing of my tank 10/8/11
I've read the three pages on the website dedicated to Silastic. I have a few remaining questions if you don't mind. I still don't know what could be causing this discoloration. You said I could kill it with bleach, does that
mean it's caused by something such as algae?
<Could well be... though a biological agent is most logical>
How can I prevent its spread?
<Remove the present colony>
If I use bleach should I fill the tank with ten parts water and one part bleach?
<This is about right... for household strength chlorine bleach... do take care to not spill... leave windows open... Use in the tank w/ all else removed>
From the inside I can see some discoloration too (attached as image 053), but from the outside it still looks like no discoloration in the seam between the glass panels.
Also, if you notice in the pictures the silicone looks thin; I can see the glass pane. The corners look all black when I'm not inspecting it closely, but on the two front corners of the tank when I look close I can see the glass pane, just like you see in the pictures. Is this a sign of the silicone thinning and becoming unreliable, or am I overthinking things?
<Could well be that the seal here has been compromised... IF in doubt, you might want to consider (carefully) cutting apart the glass to glass seal and replacing>
Sorry for all the questions. I've been torturing myself over what to do with this tank over the past couple weeks. I've put a lot of seat and blood into it and I'd like to use it if possible. I've filled it and drained it and it holds water, I just want to know if I can go ahead and start my first reef tank. Thanks again for the time you take to answer e-mails like these.
(I've reattached the pictures just in case they don't show up in this reply
e-mail; picture 0015 and 0017 are pictures of the front of the corners and silicone should be visible there. Picture 0016 is a side picture of the corner and the visibility of the glass pane shouldn't be a concern.
<Cheers, Bob Fenner>

Proper Storage Of Glass Fish Tank -- 06/30/11
My husband is in the military and we anticipate moving frequently in the next two to three years.
<<Ah yes'¦>>
We would like to put our 220 gallon glass fish tank into long-term storage, but have been told that storage will ruin the silicone seals. Is this true?
<<Mmm, perhaps under 'extreme' conditions'¦but not something I have ever seen or experienced. As a 20-year veteran myself, I had occasion to store aquariums for long periods and never had problems with the silicone from such storage>>
If so, is there anything that can be done to preserve the seals during storage?
<<A bigger concern I think is to make sure the tank is cleaned thoroughly. Any leftover mineral deposits will only become that much harder to remove, and may even mar/etch the glass. A good scrub with a mild vinegar solution, followed by a good rinse with clear water, is in order here. Other than cleaning, I don't think there's much else you need be concerned with (or can do much about) here>>
Thank you,
<<Happy to share'¦ EricR>>

Removing silicone (RMF, anything to add?)>><< 09/29/10
I was given a 38 gallon home made tank. It's basically a wood box with a large window in the front. I really like it, but, alas, it had a small leak at the bottom of the window. Here it is with my newest fish in it. ;)
<Looks remarkably like a some kind of human livebearer, perhaps an immature male of the species Homo sapiens.>>>My guess as well. RMF<<
That little fish is the actual budding hobbyist here. I'm definitely not too upset about it, though. I'm actually enjoying it a lot, too! I can't wait to get this big tank up and running!!
<I bet! It's a good size, and shallow but long shape will be neat for a mountain stream type set up with lots of small fish such as Danios, a good strong current from one end, and some boulders and sand on the bottom.>
I've gotten the glass out and used a razor blade to scrape out the bulk of the silicone out. Any suggestions on how to remove the rest off of painted wood
<Do read here:
There are tips there like using hot but not boiling water to soften the silicone and then letting the tank soak for a while. You can use an old fashioned razor blade or a wall scraper to work away the silicone. The main thing is to remove as much silicone as is practical and then seal, cure, and above all test the repaired tank somewhat waterproof (a patio or garage is great) before bringing it indoors.>
The folks that made it and gave it to me swear getting the bulk of it out will be sufficient, but I do NOT want to have to do this again, and rather trust the many, many times I've seen it said on your site and others that it must ALL be removed.
<Yes, this is generally the best approach. Even if one part isn't leaking now, it may do so a year from now, so you may as well replace all the silicone with fresh sealant.>
Right now I'm trying a pumice stone and a bit of Isopropyl alcohol and it seems to be working much better than the razor blade (but oh my the mess!)
but I also don't want to scratch all the paint off of the wood if I can help it.
<Understandable. But I suspect you'll need to patch up some of the paintwork anyway.>
<Hope this helps. Cheers, Neale.>>>Take your time... lots of single edged razor blades... maybe a good holder for same. Keep out of reach of the child/ren. RMF<<


Re: More re: Removing silicone 9/29/10
How long would you let the silicone cure before a test fill?
<Will state on the package. Typically 24 hours, but may be longer. Be sure to use aquarium-safe silicone rather than generic silicone, the latter containing antifungal chemicals toxic to fish. Cheers, Neale.>
Re: More re: Removing silicone... and sand again
Thanks, Neale! I got impatient and did the test fill last night. It had been 24 hours. Used the GE 1* W&D. SUCCESS!!!! :D My very first repair job and no leaks!!
<Well done!>
Granted this has to have been a much easier repair than an all glass aquarium, and I also have the benefit of water pressure pushing the joint tighter instead of threatening to pop the seam.
I've been looking at sand, and I think play sand will be the best I can afford as I'll need over 50lbs of it.
<Many people have indeed used play sand, pool filter sand, and various other types of sand.>
I see it mentioned as safe on many sites, do you concur? It also looks like Natalie (if memory serves) uses it regularly?
<The bottom line is that is if it is [a] non-calcareous and [b] smooth rather than sharp (technical terms that mean precisely what they sound like) then any sand should be fine in an aquarium. You can test the lime-content of sand easily enough yourself by adding some vinegar and seeing if the sand fizzes; if it does, then it's not non-calcareous and will raise the carbonate hardness and pH over time. That may or may not be a deal breaker depending on the types of fish you're keeping. As for sharpness, if it feels smooth and silky rather than abrasive, then it's probably smooth sand, and therefore unlikely to scratch burrowing or bottom-dwelling fish. I have to admit that I resolutely stick to recommending only horticultural smooth silica sand precisely because you can guarantee it'll be lime-free and non-abrasive. Other types of sand may or may not be safe, but there's no copper-bottomed guarantee I can offer you via e-mail. For what it's worth, a 25 kilo (~50 lb) bag of smooth silver sand from my local garden centre costs about £4, or about $6. Whatever sand you plan to use, be sure to clean it thoroughly before use. Cheers, Neale.>

black spots in silicone sealant [RMF, better idea?] 7/8/10
I had a newly glass tank last month ago. I raised the one green Arowana ( 9 inches long ) and 15 Koi ( 3 inches long ) since last month. After 2 weeks, I noticed the blacks spots on silicone sealant. At first , it is small in number and their sizes were also small. But after some days these black spots become numerous and becoming bigger in size ( now they are 5 mm in diameter, but some are bigger ). I've tried many methods to get rid of them ( rubbing , scratching ,............) , but all were failed. These black spots are seemed to be buried into the sealant.
Please , inform me " what is this problem and how to solve it " with regards
Mr. Myint Aung
<Hello. My guess would be that the black spots are algae or fungus. If there are gaps between the sealant and the glass, water will seep in. If that happens, algae and fungal spores will get into the gaps. They are harmless, but unsightly. If you want to get rid of them you will need to scrape the affected sealant off and re-seal the panes of glass together.
Cheers, Neale.><<Mmm, I'd return/exchange this tank with the dealer it was purchased from... the likelihood of structural failure is small, but... BobF>>

Re: black spots in silicone sealant [RMF, better idea?] 7/8/10
Thanks a lot for your kindly reply. Your suggestion is very useful to me.
Please instruct me how to prevent the growth of algae or fuge. My glass tank's size is 84 inches ( Length ) x 2.5 inches ( width ) x 3.5 inches (height ) . I don't want to use antialgae or antifugal agents because I'm afraid of that will harm to my fish somehow in long term. Is daily water change ( 20 %) needed to prevent the further growth of algae or fugi . Or should I need to add the table salt to water every time after water change?
Or other suggestions
with regards
Mr. Myint Aung
<The only process I've had luck/success with is taking such tanks "down"... removing livestock... and chlorine bleaching them over a few days time. Unfortunately, in almost all cases, the "spots" will/do return. BobF>
Re: black spots in silicone sealant [RMF, better idea?] Neale's go 7/8/10
Thanks a lot for your kindly reply.
<Happy to help.>
Your suggestion is very useful to me. Please instruct me how to prevent the growth of algae or fugi.
<You can't.>
My glass tank's size is 84 inches ( Length ) x 2.5 inches ( width ) x 3.5 inches (height ) . I don't want to use antialgae or antifugal agents because I'm afraid of that will harm to my fish somehow in long term.
<Correct. This is why aquarium sealant is different to sealant used in homes and cars.>
Is daily water change ( 20 %) needed to prevent the further growth of algae or fugi .
<Will make no difference.>
Or should I need to add the table salt to water every time after water change ?
<Won't make any difference.>
Or other suggestions
<There are none. As Bob Fenner said, you may want to return this aquarium.>
with regards
Mr. Myint Aung
<Cheers, Neale.>

Re: black spots in silicone sealant [RMF, better idea?] 7/10/10
Thanks a lot for your kindly useful reply
As you advice, I'll plan to bath my glass tank with bleach for 3 days.
Before starting , let's me know some points as follow :
(1) can bleaching procedure affect the adhesiveness of sealant to glass
<Not appreciably, no>
(2) which type of bleaching types shall I use ( sodium hypochlorite or calcium hypochlorite....etc.)
<Either is fine. I prefer the Sodium for lack of "scaling">
(3) how strength of bleaching shall I use ( roughly )
<Five to ten percent by volume should work from stock, liquid, consumer concentration>
with regards
Mr. Myint Aung
<Bob Fenner>

enquiry 7/11/10
As your advice , I'll plan to bath my tank with sodium hypochlorite.
Here, I sent these photos of black spots on sealant .
with regards
Mr. Myint Aung
<Okay... you might want to check w/ whomever made this tank re the sealant product he used. BobF>

Can I fix my aquarium? Crack... Plexi for glass repairs... 6/29/10
<Hello Helen.>
I have read, read, and reread, the many posts on how to fix cracked aquariums. Now I am just totally confused! Please tell me what you think.
It is a 125 gallon that has a u shaped crack on each end of the bottom. I have no money to replace this tank and so must either fix it or forget it.
It is was originally fixed with a Plexiglas panel that measured 12 x 18 and which was sandwiched with silicone over each crack. The panels were thin and not really done properly, I think.
<They are not. If this is an acrylic tank then silicone should have never been used. If this is a glass tank (which I am assuming here) then Plexi should have never been used. Silicone will not bond to plastics in any sort of meaningful way.>
One of them came off very easily but the other took some work to get off.
I have removed the interior silicone and am now wondering what to do. I don't need any more disasters as these past couple of years have been pretty traumatic for me but I would so love to get this tank up and going. Fish can be so wonderful and very therapeutic, and this tank is my dream tank.
Although this aquarium is an oldie I feel it deserves a chance to be fully functional again, sort of like me!
So, what do you suggest?
<If this is indeed a glass tank the only thing I would personally be comfortable with is replacing the whole panel. A full panel patch may work, but the bottom of a tank is nothing to take a chance on. If the bottom panel is "boxed in", that is inside the side panes you may well be able to break it out, cut out all silicone in the tank, replace the panel and then reseal the entire interior of the tank. If this tank was built with the sides sitting on the bottom you will need to carefully dismantle the entire tank, remove all silicone and then reassemble with a new bottom.
Either way it is a ton of work and a new bottom panel may not be cheap (glass varies widely, call all you can for quotes). Knowing what many will charge for such a panel you may very well be better off buying a new tank used. This is the time of year to look, you may be surprised at how cheap you can find one of these. I in fact have one that I just want to get rid of! If you are anywhere near the center of California do let me know!>
Thank you for the chance to ask.
Helen Tucker
Virginia Beach, Virginia
<Welcome, dang, nowhere near CA! Do look a bit for used tanks, local classifieds or Craigslist. It will be less trouble and quite possibly
cheaper for you. Scott V.>
<Bob, if you would not mind posting, I do actually have a 125 tank stand and canopy free to a good home in Fresno, CA if anyone is interested they can email me at acrofrag@gmail.com><<Will do, have done. B>>

proper way to store a tank 6/25/10
I have a 58 gallon tank that I want to store in my garage for maybe a year.
What should I do so the silicone seams stay ok?
<Just keep the tank in a cool/er, dry area... maybe up, off the floor, with cardboard under it, perhaps around the sides, to discount easy breakage>
<Welcome. Bob Fenner>

Emergency leak in my 180 gallon! 4/20/10
Dear WWM crew,
First of all, let me congratulate you on being *the* source for all things marine related. =)
I had my 180 gallon reef tank spring a leak near one of the bottom seams last night...NIGHTMARE. Fortunately, I had recently set up a 70 gallon reef nearby (I loved the big one sooooo much, I had to set up another) and I was able to corral all the critters, remove the live rock, and drain the big tank to re-silicone the seams. My concern stems from two factors; 1. The new tank had only been cycling for 2 and a half weeks
AND 2. I have a lot of animals in a 70 gallon aquarium.
Here is the list:
Mandarin Dragonette (2 inch)
Lawn Mower Blenny (3 in)
Naso Tang (8 in)
Sohal Tang (6in)
Yellow Tang (4 in)
Snowflake Eel (16 in)
Humbug Damsel (2 in)
Lunar Wrasse (5 in)
Rabbit Fish (4 in)
Yellow-Tail Damsel (2 in)
30 hermits
12 snails (Turbo, Nass., Astrea)
4 serpent stars
1 sand-shifting star
<Feed VERY sparingly if at all... Monitor ammonia, nitrite... Have a good deal of water on hand, pre-mixed>
The coral is all in large 30 gallon tubs with 1 powerhead in each for water movement. I didn't want to put the coral or LR in the new tank, as the old one had a touch of the Aiptasia and I didn't want to contaminate the new tank. The Sohal and the Naso don't seem very happy about these developments.... and I can't say I blame them. Would I be better off moving the two large guys to separate tubs with the coral?
<Mmm, maybe float the Sohal in a large plastic colander in the 70>
The silicon takes 48 hours to set and harden, but I am worried about keeping this much livestock in an uncycled tank until tomorrow night.
The coral and LR is in the original big tank's "old" water...the water in the smaller tank is only a few weeks old, but it has been cycling with 40 lbs of LR almost the whole time. Should I do a water change in the smaller tank tonight to help alleviate the burden?
<Depends on NH3, NO2 readings>
Keep the lights
on, or off?
<I'd leave some outside light on, the tank light/s off>
Is the full 48 hours to let the silicone set necessary in your experience?
I feel very anxious about all of this, lol. I appreciate your help.
Thank you,
Kevin Clark
<Steady on. Bob Fenner>

Need help with Possible Cupramine Interaction 3/27/10
I have been looking for a possible solution to a situation I recently had that resulted in the death of multiple fish while in quarantine. I have looked on numerous places on the net but have not been able to find anything that matches what happened.
I purchased 3 red striped Cardinalfish and 2 neon gobies. My plan was to place them into a QT tank first as I had issues with marine Ick in the past and don't want to rip down my main display tank again. Learned my lesson. All new purchases go into quarantine first.
<Okay... you might peruse WWM re this issue. I am not a strict adherent to this mantra... there are several fish families/groups that are better NOT quarantined... the Gobiosoma/Elacatinus among them>
I mixed new salt water using tap water (I know I should use RO but don't have a RO unit yet) filled the QT
<I'd use water from a clean, established system for quarantine, unless I could/was very sure of its quality>
and then added Stress Zyme to remove any chlorine that may be in the tap water. I then waited a couple of days before adding the fish. I also tested the water parameters prior to adding the fish and the ammonia, nitrite, and nitrate where all 0, PH was at 8.4, salinity was 1.023 and temperature was 77F. So everything looked good.
I then purchased and slowly acclimated the fish into my quarantine tank (bare tank) and then watched them for two days so that they had a chance to adjust and I could make sure they were eating OK. Everything was look good. Fish were eating, swimming and breathing normally. Basically looking good. My plan then was to do a treatment with Cupramine
<And I would not expose Gobies, and again that Middle English derived word, several fish families/groups to copper products. Read here:
and the linked files above>
after they settled so I could ensure that I would not have an issue once put into my display tank.
<You won't, because they'll likely be dead>
I was doing this as I have had issues with fish acquired from our only LFS store in the past and don't want a repeat. I should also note that I have used Cupramine in the past without issue.
Since I am aware that fish like gobies can be sensitive to a copper treatment I started with 1/2 of the recommended amount
<Copper strength is a threshold event experience... i.e., not having a physiological dose (concentration) does no good... Is actually harmful. Do you understand this?>
(Cupramine: 1/2ml per 10.5 gal instead of 1ml per 10.5 gal recommended) for the first day.
The quarantine tank is 30 gallons so I added 1.5ml. I was going to add the other half dose after 48hrs and then again to achieve a final concentration of 0.3-0.4 mg/l, slightly under the recommended 0.5 mg/l.
I had tested the water after a couple of hours after adding the initial copper dose and it was at ~0.1 mg/l
<This with a chelated copper test kit?>
which is where it should have been at. I am using the Salifert copper test kit. Within 24 hours all 3 of the red stripped Cardinalfish were dead and the gobies (not dead yet) looked like they had copper poisoning. I had not yet added the second dose. One was sitting lifeless at the bottom and the other looked like it was convulsing. After I discovered that the fish died, I immediately tested for ammonia, nitrite, nitrate and PH. Ammonia: 0, nitrite: 0, nitrate: 0, PH 8.4, temp 77F. I also retested the copper and it was still at 0.1 mg/l.
<Mmm, I'd be reading re testing for Cu++... and checking your test kit against one of known accuracy, with test batch water and the Cupramine added>
Both gobies have also died so obviously something went really wrong in the QT. Right now I am at a loss as to what may have gone wrong.
<... Likely copper poisoning>
So I would like to know if the stress-zyme caused the Cupramine to go from Cu+2 to Cu+ and become lethal.
<Mmm, don't think so... am very familiar with this API product, its constituents... if anything, if there was some active StressZyme left in solution, it would serve to precipitate the Cu>
I did find that you can't use Amquel as this will happen
<Really? What specific component does what with the free copper or its alkano-amine complex?>
so is it possible that using stress-zyme prior to adding the Cupramine caused this to happen or is it possible that there may have been something in the tap water that caused this. Any insight would be appreciated as I don't want a repeat.
Thanks Dan
<Again... please read where you were referred. I would NOT quarantine these two families of fishes period... Dips/baths and summary placement is advised. Bob Fenner>

Re: Need help with Possible Cupramine Interaction 3/28/10
Thanks for the insight. I was not aware that exposing gobies and Cardinalfish to Cupramine was a bad thing.
<Is too toxic for these fishes to be safe, effective>
I am not exactly sure what you mean about " not having a physiological dose does not good... Is actually harmful"
If you mean that to have it remain below the level that works then I understand.
<In part this is so, the other element is that instead of "achieving" anything positive, sub-clinical concentrations poison the hosts. Think of successive approximation events instead... a little kiss from your aunt may not count as a kiss to you, but pregnant is pregnant... This latter is akin to sufficient ranges of copper exposure... a threshold event>
My thought that building up more slowly would be a better approach but apparently this is incorrect. I will not pursue this in the future.
In regards to your question about Amquel, there was a post on the Seachem forums and also on multiple other boards about this.
<Would you please send along this/these links?>
But the one thing that I did not indicate in my first post (as I did not consider it an issue at the time) and I believe may have actually added to the problem is that this was a tank I just re-sealed. I used GE Silicone II glass (100% pure silicone - clear). I did let it dry for several weeks before using it so I dont think that was the issue but, upon a closer read on the tube I noticed that it contains a mold inhibitor.
<Mmm, the 100% product should not>
I should note that this is not obvious and was only something I discovered after re-reading the tube several times and was clued into after looking for a possible answer to my initial problem. I have re-sealed numerous tanks over the years and always used GE clear silicone without incident but it seems that all the new GE silicones have this inhibitor which before they never had.
<This mold inhibitor IS toxic>
So I think what happened was when I removed the carbon and added the Cupramine, the inhibitor combined with the Cupramine caused the water to turn poisonous.
<Is toxic on its own... I don't know of any synergistic effect/s>
I do not have a way to know for sure so I can only assume. I think the reason that everything was OK for the first few days was due to having carbon in the filter. It was probably absorbing anything that was being leached.
Again thanks for the information. I am always trying to learn more to do the right thing.
<Thank you, BobF>

Re: Need help with Possible Cupramine Interaction - 03/28/10
Thanks for the explanation on the sue of Cupramine. Much Appreciated.
As for the use of GE II clear, it is listed as 100% silicone but if you look at the fine print on the back of the tube, then you will see where it says "...that also provides mold free product protection". This is on the Silicone II Clear Premium Waterproof Silicone for Window/Door/Attic/Basement and listed as 100% Silicone.
<Oooh, I sense a big lawsuit here... How can anything be 100%... plus something else?>
Here are the links you requested.
Here is the response from Seachem on their forum:
Re: after Cupramine dosing, can Amquel be added
Once you have finished treating with Cupramine and the copper has been removed from your tank, it is safe to add a water conditioner, such as AmQuel, to combat ammonia. We do not recommend using both products at the same
time, as water conditioners are reducing agents that could reduce the copper to a toxic form.
If you need to perform a water change to lower ammonia levels during the course of treatment, just be sure to re-dose the Cupramine to bring it back up to a therapeutic level.
<Mmm, yes... conversion of Cu++ to Cu+...
Back to my standard suggestion to not use such "Dechlorinator et al. products"... and just pre-mix and store new synthetic seawater if this is the purpose, or skip such conditioners altogether, as both chlorine and "amines" are complexed almost immediately on contact with seawater. Bob Fenner>

Resealing a turtle tank - tiny bubbles in seal 3/2/10
Hello, I just love reading all the questions and answers on your site.
Really helps! But I am paranoid and wanted to ask a question that I didn't see answered.
I have a 55 gallon aquarium, 16 years old, which used to house desert reptiles (chuckwallas).
<Mmm, first question, was this tank built/intended for aquarium use? There are "reptile tanks" that are of thinner glass construction that are dangerous to "fill all the way" w/ water. The glass should be at least 3/8" if this tank is 22" tall>
It's been used for my red-eared slider turtle for the past 9-10 years. It is only filled halfway and has never had a problem.
I was doing a very thorough cleaning and noticed the silicone was stiff, shredding and coming loose from the glass in a few places, probably from the years of dryness and tiny digging claws.
<Mmm, this should be "okay"... it's the Silicone "between the glass" at the joints/corners that is really the functional seal>
I took a razor blade and some alcohol and removed all the old interior seals. What an arduous process!
<Yes... there are worthwhile tools for holding single edged razor blades>
I applied fresh aquarium silicone using a masking tape border and mostly it came out okay, but I didn't realize how quickly it sets so in a few places it is lumpy and rough where I tried to "smooth" it after it has started curing. I plan to water-test it after 72 hours.
<? Was it actually leaking before? If so, it's best (though not necessarily needed if the tank is only half filled) to cut the panes apart and re-seal all>
This morning when I inspected it I saw some small air bubbles in the vertical seams, the largest is maybe 1/8 inch wide and 1/4 inch tall. Most are teeny and along the joints, which are clean and unbroken.
<Ah, good>
Do I have to start over? I am exhausted, and my turtle is so unhappy in his temporary house! Thanks so much for your time!
<No to starting over. You should be fine here. Do take a read:
and the linked files above if you'd like further input. Bob Fenner>
Re: Resealing a turtle tank - tiny bubbles in seal

Thank you SO much for the prompt reply!
<Welcome Becca>
I had read everything in the Silastic forums and the FAQ but I was still nervous. The glass is 1/4" in the front and back, and 3/16" side panels, so it probably was originally meant for terrarium use.
<Yes. Am glad I asked, and that you have measured, responded>
I keep it filled about 40% full. It will never be filled with water in my house! It has very solid plastic frames on the top and bottom with good braces. It sits on a solid base of 3/4" plywood on a metal stand. It hasn't leaked in 10 years, so I am just hoping I didn't somehow screw it up by replacing the inner seals!
<Not to worry>
I didn't stick the
razorblade into the joints, I'm just respectful of Murphy and his Law! :)
<Heeee! I wish I were more often>
Thank you again,
Rebecca and her turtle Number Nine (he was a rescue and had a nine painted on his shell for ID, the name stuck)
<Ahh, thank you for your further input, sharing. BobF>

Re: Tank seal -- 09/03/09
Have I offended you guys somehow?
<Mmm, don't think so>
Maybe I simply wasn't clear enough in my question. I replied to a previous email from the crew with an update question two weeks ago and have yet to hear back. I thought maybe I'd rephrase here.
<Okay! I do think, BTW, that I'd remember your email if I saw it... Have a friend here in San Diego with a son with your same name. For you and browsers... our ding dang (pardon my language) spam-sorter has a "mind of its own"... and though I try (when I do it) to sort through what it has pulled for discarding; methinks a good deal of real mail is not getting to us>
I put together a glass only tank a year ago and filled it up to test. It did hold water for about 2 months. So I decided to drain it in preparation for moving it into the house to set up. At that point I noticed some fatigue/stress in the glass to glass seams. I emailed pictures and the verdict was that the risk was too great. I subsequently let it sit until I could decide what to do next. One option was to cut the seams, separate the glass, clean, and reseal.
<Am with you so far>
I haven't done that to date and frankly, it looks to be a nearly impossible job.
<Nah, just a pain in the keester... have done it a few times m'self>
I have a glass workers special tool that he said I could use to cut the seam (basically, a glorified razor blade with an extended handle). But there is essentially no gap in the glass to glass silicone seal. I view this as very difficult if not nearly impossible to separate as I wouldn't even be able to get the razor blade in between the glass panes in order to separate.
<Mmm... with care to not cut yourself, such blades can be forced... actually do make a gap...>
One other thought I had was that perhaps I might just take off the inner seal, glue in another full pane of glass next to the original side panel of the aquarium, and then redo the interior seams.
<A worthwhile possibility!>
It seems to me this would reduce some of the pressure load on the original piece of glass, basically an extended bracing job. I just don't know if this will work or not.
<I do think it would. Such repairs are done on Acrylic tanks that fail... with good success>
In your experience, has this type of action been done successfully and saved a tank from catastrophic failure?
<Am not familiar with such attempts with glass... but don't see why it would not work>
I know it wouldn't be the most visually appealing tank (at least from the side), but would it provide the desired functionality?
<If in a back corner or corners not likely obvious at all... and if done well in all four corners, might well be ornamental in appearance... In all cases, in time I doubt anyone will notice.>
Tank was 1/2" thick all panes. 72" L x30" W x29" H all panels resting on a tempered glass bottom panel. Side panes in between front and back panes
of glass.
<Do please take some pix of the before and after job and send them along for others edification. Bob Fenner>
re: tank seal
Wow, quick reply. Thank you. I'll let you know how it turns out.
<Please do Mike. BobF>

Washing Newly Built Tank 7/9/09
I have just built my first aquarium, and I was wondering what the best thing to wash it with to make sure there are no toxins coming from the silicone? (before I put my fish in it)
<No need to wash with anything, just allow the silicone to fully cure and rinse out the tank with fresh water.
James (Salty Dog)>

Sealant, for FW decor and SW tank f's 7/7/09
Dear Mr. Fenner,
In the Daily FAQ's today I noticed a question about aquarium safe silicone. While 100% silicone is most often perfectly safe, I'd like to point out that trace ingredients and curing agents do not factor into this analysis (pigments also may leach into water). In my experience, GE Silicone 1 Clear WITHOUT Bioseal is the fastest-curing, strongest, and safest silicone (no, I'm not paid by GE). I believe this is a slight variant of the All-Glass tank silicone, which is contracted out to GE.
Just my 2 cents,
Will N.
<Thanks much for this input Will. Will post, accumulate. BobF>

Small hole in silicone bubble [Scott V] 6/11/09
Hey Scott, how's it going???
<Great! Hello Jeremiah.>
How is the "without borders" thing going for ya??
<Wearing, but recovering, just about there.>
Well figured I'd give an update and of course ask another question hehe!?
Finally picked up a 75 gallon Starphire tank from Glasscages down in TN.
Got all my plumbing stuff from Mike, got all excited, started filling it, letting it run with water. The Starphire looks so good you really can't tell there is water in it!
<It is some neat glass.>
Unfortunately the guy drilled the closed loop hole in the wrong spot, there was a few scratches on the glass, 2 in the front, all over the top brace, all the silicone looked like my 1st grader did it and the list goes on. I can deal with all this so far though, I was warned by you and others that it wasn't top notch finish work.
<I could tell you of many similar stories.>
Well I noticed there were a few bubbles in the silicone between the 2" glass brace that goes all the way around the bottom and the bottom pane of glass on the inside. One of those bubbles has a hole the size of a pin head in it and leaks a very small amount of water between the glass panes, not reaching the outside where I can feel it or anything though.
<Between the glass panes, panels of the tank, or between the panel of the tank and this goofy brace?>
The bubble is about 1/8" wide. Question....how do you recommend I fix it?
<I would not.>
I don't want it to get any worse! Will silicone adhere to silicone, can I just fill the small hole or silicone completely over the bubble to where the silicone reaches uncaulked glass?
<Silicone does not really adhere to already cured silicone. I would extend this beyond a bit if you can.>
Should I silicone over the other bubbles just in case? What do you suggest?
Thanks in advance again for your help in? another tank trauma!!!? Chat soon.
<If the seam between the actual panels of the tank is ok and intact I really would not worry at all about this. I do suspect what you are saying is it is leaking between the brace along the bottom and the tank? These braces are not really needed, installed along the wrong plane to prevent the deflection they are meant to prevent anyhow. IF it is indeed letting water in between the actual panels of the tank DO call Glass-Cages ASAP.
It is a manufacturing defect that should be taken care of. You can yourself, but it is so much work, this is why you paid somebody else to do it!>
<Talk soon>
Re: Small hole in silicone bubble [Scott V] 6/11/09

Hey Scott, good to hear everything is going good and thanks for the reply!
Ok, Yes it is a goofy brace, and I've already let Glasscages know, they replied with a one line incomplete sentence saying "you didn't say it was leaking, just that you seen a bubble?" AAAHHHHHHHHHH!!!!? When you said "I do suspect what you are saying is it is leaking between the brace along the bottom and the tank?" YES, it is above the bottom panel, below the stupid brace, the hole being on the inside of the tank! Not actually coming out where the tank panels meet. I could see the water between panes, granted its a small amount, but I got a little nervous thinking it would eventually get/make things worse etc! That's why I wanted to fix/correct the problem now while its small. So you think this won't be a problem?
<Not at all, this brace does not even need to be there.>
Fingers crossed!!! You are absolutely right kind sir, that is why I paid them, unfortunately, with their BBB score of F, they are less than easy to deal with! So ultimately, whatever problems I end up having with this tank, they ARE MY problems and my problems alone.
<Unfortunately this again is what I hear re.>
I'm starting to think to heck with gambling with my Starphire and going and getting a stock tank and drilling it myself.
<This is their big draw, a cheap source of Starphire.>
I don't know, I just don't want to get knee deep in this hobby etc and start having tank malfunctions and have to start all over again. Is this the reef blues? Gives complete meaning to, if its not one thing...its another! Thanks again Scott!
Talk with ya soon man! A maybe future reefer!
<Welcome my friend. Do not let this concern/worry you. It is just a cosmetic issue. Of all the things I have heard over the years about this company I have never heard one single story of any of their tanks failing.
Scott V.>

Re: Misaligned seams 02/08/09
Mr. Fenner,
Here are a couple pictures of the seam that is misaligned (first two pictures). I also attached two pictures of a small defect/crack on the edge of the other side panel where it joins with the front panel (last two pictures) that I noticed shortly after I had it filled and stocked about a year ago, but I thought I would get your expert opinion on this one as well.
<This crack is more problematical... appears to be about mid way in depth... I would Silicon a small piece of glass (maybe two inches wide) over this area, about six or more inches in height... over the area, flush to the edge, on the outside>
It caused a small bubble in the silicone, and has showed no signs of expanding. I appreciate your advice. I bought the tank with little experience unfortunately and not realizing a thorough inspection was so important. But the more I
have read, the more I start noticing things and I wanted a little reassurance on these two flaws. Thank you so much for your quick reply!
<The misalignment itself is not a worry here. Bob Fenner>

Re: Misaligned seams 02/08/09
Mr. Fenner,
<Msieu Krispinsky>
In your experience, have you seen cracks like that lead to complete failure of the seam or just a leak if not reinforced? This should be my last question.
Thanks again!
<Rarely... but on a few occasions... ergo, best to make a comment, be "safer" than sorry. Understanzee? BobF>

Re: Misaligned seams 02/08/09
Say no more....thank you sir.
<Welcome Luke. BobF>

Re: 45-40 then back to 45 Buying Silicon For Tank Repair 1/16/2009 Hi again, i was just wondering, what types of silicone are toxic, and what should i do? Will it eventually fade away and be fine, or do I have to redo the whole tank? Thanks. < When you buy silicon you need to look at the labels for a silicon that is stated that it safe for aquarium use. This is usually sold at aquarium shops and sometimes sold at hardware stores. Most of the silicon sold at hardware stores is for use around bathrooms and sinks. It is used in areas that are prone to mold. They add an ingredient to prevent mildew and fungus from growing. Look at the brand of silicon you bought and look for a website. Look up the website and try to find a contact. Ask them about the their silicon and if it is safe for aquarium use. I would still do water changes to dilute any toxins and probably add some good quality carbon to the filter.-Chuck>
Power Blue silicone eater, aquarium integrity 12/07/08
I have a 95 gal. with a xl power blue tang who has decided that the silicone seals in my tank taste good. He has been removed but now I am looking at my tank and in some places he ate it pretty clean. I am worried about it leaking and plan to replace it just not right away (not an option unless it explodes). How safe/unsafe is my tank in your opinion?
The seal is still intact between the glass just very worried as it is toward the very bottom of the seals. I have never seen anything in a reef go at the silicone seals have you seen this before? Thanks a lot.
<The sealant in the corners is more to protect the real structural bond... which is between the glass faces... In fact there are a few very fine lines/manufacturers of aquariums (e.g. Juwel) that don't have the corner beads at all. Not to worry. Bob Fenner>

Re: Power Blue silicone eater 12/07/08
Thanks a lot u r awesome. I renamed that fish "Hollywood" (full of silicone).
You are great for what u do and know Thanks again
<Heeee! Welcome. BobF>

Silicone, use 11/30/08
Can a person use 100% silicone caulking from Lowes in a aquarium?
<Sure can, just be sure it is truly 100%. Many will have mildewcides or "biocides" in them, marked somewhere on the tube.>
<Welcome, Scott V.>

Tank Seam 10/27/08 This is a glass only tank I glued together with silicone. I water tested it freshwater only for 2 months with no leaks. As I was draining the tank to move it back indoors, I noticed some concerning signs of stress in the seams where glass meets glass. I thought I'd run it by you for your comments regarding. Do you think this is a safe based on the picture? <The seam is questionable, too much so IMO. The tank may serve well for years, or (more likely) it could fail catastrophically in short order. Was the seam fine before filling it? If so it is indicative of a seam that is failing, will get worse and bust in time. When the glass was cut was there room left for the silicone? There should not be, the glass should fit snug. Leaving room for the silicone is not necessary and makes for a weaker joint. Scott V.>
Re: Tank Seam 10/28/08 No gap left for silicone during construction. Snug fit glass to glass. <Good.> Seam was ok prior to filling with water and didn't see it to this extent during most of the test time. <A telling sign, the seam is changing/will fail.> By catastrophic failure...does that mean the tank essentially explodes, cracks, or slow leak? <The first two.> I'm assuming it means the whole panel could burst at some future point in time. <Yes.> Funny thing is it seemed to get worse as I was taking water out of the tank. Not sure what that might mean. <The seam was stressed with water in the tank, came apart when emptied.> This is a 280 gallon tank, so I'm afraid it might not be worth the risk. <It is not, I would take this apart a redo. Quite a bit of work, but worth it. Scott V.> Re: Tank Seam 10/28/08 Do you think it is possible to just redo the one glass panel or must it be all panels from scratch? <You can just cut out the one panel and redo. The problem is that silicone will not adhere to cured silicone well, it will eventually leak. So, if you are going to go this route you will need to cut out/clean off the entire inner seal (the bead run around the inside of the tank). Your repair will hold the panel in place, the replacement of the inner bead will seal it. Scott V.> Mike Cox

Tank Reinforcement 10/3/08
I have a 225 gallon homemade tank. It is 6 feet long 24 inches wide and 30 inches high. The glass is 14mm thick. The seals between the glass panels don't look too good. There are a lot of bubbles and some gaps that go almost all the way across the thickness of the glass.
<Not good.>
There is no center support on the top on the tank. Can I silicone a strip of glass (1/2in x1/2in x length of seam) in all the corners to reinforce all the seams.
<While you could silicone glass at each joint, ½' strips just will not do the trick. Given the sound of these joints I would just disassemble the tank, thoroughly clean off all the old silicone and start over. This is a ton of work, but it is the only 'right way'. Re-dos and time is the price we sometimes pay for DIY! Some bubbles in the seam are normal, but many (especially the larger ones) will spell disaster. If you have never tackled a project like this before I highly suggest either practicing first on a smaller scale or employing the help of somebody with experience. Do also be sure that the glass is fit well together; do not leave a small gap for the silicone. This is a common mistake, this gap will only weaken the joint and allow the air bubbles.>
I read what you said about adding a center support.
<I would definitely add the center support for a DIY tank of this size. Good luck, Scott V.>

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