Glass vs. Acrylic
Hi Bob et al,
I am going to be buying an 800g aquarium in the near future and am pretty much sold on glass versus acrylic for the sole reason of scratch resistance.  I am concerned about the seals of the aquarium and how long they typically last.  I would really rather not have to drain this large reef aquarium in the future to reseal it.  Any idea how long silicone seals typically last in saltwater tanks?  Do you know of any acrylic tank manufacturers that sell tanks with more scratch resistance than the older acrylic tanks?  Thanks for your time! Dave
<This is pretty straight forward..... The seals are a non-issue. They last as long as you will. The problem with your logic is, glass scratches too, and is permanent. Acrylic can be scratched easier, but can be polished (even under water) to resolve the problem. It is also lighter, stronger and better resistant to earthquake if that is a concern. It is easier to drill, install overflows, plumbing, etc. It is also more expensive. The scratch issue isn't as vital as you think. I have a few acrylic tanks and I don't have any visually distracting scratches or any I've had to polish. I *have* returned glass tanks with permanent scratches.
Hope this helps!  Craig>

Acrylic questions
Bob,
A couple of questions for you regarding acrylic and its use in sump/tank construction:
1) What type/brand of acrylic would you recommend for aquarium construction.
There are many types: Plexiglas, Acrylite, Optix, etc, and I'm not sure which one (if any of these) are appropriate for aquariums (i.e.. transmit PAR light, maintain rigidity-avoid warping, avoid discoloration, etc).
<Hmm, actually most acrylics are pretty much the same. What people call them are more brand names then different formulations. I am a big fan of Reynolds as a manufacturer...>
2) What type of acrylic cement is best for capillary bonding acrylic in aquariums (Weld-on#3 ?).
<Weld-on for sure... Number three is okay... look for/use a "gel" type if this is one of your first tries at making acrylic anything>
3) What type of acrylic would you recommend for filtering UV while allowing other light to transmit freely (esp. PAR).
<Again, just whatever type you can find that is reasonably inexpensive of about the right thickness. I would not transmit "useful" light through the acrylic... shine it directly into the water>
Lastly, I've found a fluidized bed filter used in the shrimp aquaculture industry that's rated at handling 2 lbs of shrimp feed per day. Any guess at how much raw live rock this filter could handle if I used it in the curing process - along with heavy skimming (i.e.. skimmer output set to 5 times the number of gallons of water, with 1 gallon of water per lb of Fiji rock in the curing tank).
<A guess is "a bunch"... Shrimp are very dirty animals to culture... I'd guess if the folks who engineered this are saying "two pounds of shrimp feed", this equates to hundreds of pounds of live rock. Really. Bob Fenner>
Thanks!

Suitable Epoxy Paint for Plywood Aquariums
Bob,
<Anthony Calfo in your service while Bob travels>
I've been looking over your fine website and have not yet been able to pin down any brand names for epoxy (or otherwise) paint to seal plywood tanks. I've made inquiries to various paint dealers here in Kansas City and they're all very gun-shy about selling epoxy paint for an aquarium--Sherwin-Williams wants me to have a meeting with the tech rep before they'll sell it to me! Thanks for any assistance! Mark Lynn
<Mark... for smaller aquaria under 200 gallons, tub&tile epoxy (advertised as Baby safe once cured) is commonly used in aquaria. Available from your local DIY store, it is convenient if not inexpensive. For a larger project, I would take the paint rep up on the offer to protect your investment. You'll want to avoid paints with anti-fouling agents in them (for mold and mildew...very toxic to aquatics). Best regards, Anthony>

Suitable Epoxy Paint for Plywood Aquariums II
Thanks--the tanks I'm working with are around 100 gallons. Is this a paint
used for repairs to tubs, etc? MRL
<exactly, my friend. For cement laundry/wash tubs and the like. You may be a little restricted by popular home decor colors (grey, tan, white, black) but as long as it says Baby safe when cured as most do, you will be fine. Even if it doesn't you are likely safe if you are willing to test. Worst case scenario is you have to give another good coat over it. Best regards, Anthony>

Suitable Epoxy Paint for Plywood Aquariums III
Thanks, Anthony--I'll check out Lowe's and Home Depot tomorrow. I've also considered lining them with countertop laminate ($2.00/sq ft) and sealing the joints with silicon. I'll do some price comparison and go from there. Thanks again, Mark
<For what it is worth... I have used Olympic brand swimming pool paint in concrete ponds and know that they at least have a product that is fish safe. I'm just not sure if it adheres to wood as well. It was designed for concrete applications specifically.>

Suitable Epoxy Paint for Plywood Aquariums IV
I tried some UGL --formulated for concrete-- it seemed to work fine for several months, then I got a small leak. It looks like the paint cracked along some grain lines and the plywood got soaked. I let it dry for a couple of weeks, the gave it another couple of coats. Worked fine for a couple of weeks--until I added the rock--I think the extra weight of the rock caused the wood to flex just enough to make the paint crack again. MRL
<Ahhh.. yes, thank you. I'll remember that for the next query on the subject. We'll stick to ponds with it <wink>.>

Most Everything You Ever Wanted To Ask/Know About Acrylic Aquariums
Dear Bob, I have tried to put all my questions in one list. Can you help me with any of these? Thanks for your help. Mike
<<Greetings, Mike. JasonC here, and I will do my best... >>
1) What thickness of acrylic is used for 20 gallon, 50 gallon and 100 gallon tanks? 
<<Well... the answer depends on the actual dimensions of the tank. On a general rule of thumb, perhaps 3/8" for a 20 up to 1/2" for the 100 - if there were one long panel, perhaps 5/8" or up to 3/4" for larger tanks. Probably best to break out the calculator and the acrylic manufacturer's spec sheet and do some homework.>>
2) Are the top, bottom and sides of the tank all the same thickness?
<<Again, this depends on the desired dimensions of the tank. The safe assumption is that IF you are making a perfect cube, all walls can be the same thickness. If you start stretching the cube into a rectangle, then the assumption changes.>>
3) Do they use regular acrylic glue or a special glue?
<<As far as I know, it's a standard acrylic glue - creates a molecular bond.>>
4) Are the corners bent to a different radius for different size tanks?
<<Corners are bent to a different radius for different thicknesses of material and visibility.>>
5) Can a small tank be made that has glued corners instead of bent corners? <<Sure.>> 
Why are bent corners usually sold? 
<<Easier than jigging up and adhering four walls with perfect 90 degree joints.>>
5.5) What is the radius of the bend of 20, 50, and 100 gallon tanks?
<<Depends on the material.>> 
6) Is the radius of the bend for strength or for looks?
<<Both... the material would maintain is strength for a while beyond a bend that ceases to look clear.>> 
7) Is the acrylic bent on a specialized machine or is it heated with a local heating element and bent over a mold?
<<Depends on the application. On smaller panels, I have seen a blow torch used. On larger, curved aquariums a large walk-in oven is used.>>
8) Can the acrylic be trimmed to fit after it is bent or does it have to be bent perfectly?
<<Well... the whole job has to be done perfectly. Cuts, joints, bends, you don't really get a second chance on the same piece of material.>>
9) Is it very hard to bend acrylic over a mold and get a perfect bend?
<<Let's just say that it is a skill, and one that can be learned. But not so simple that you'd get it on the first try.>>
10) Are there any special tricks that you know that help in bending the front piece of acrylic? 
<<Patience, lots of patience, that and a fairly exacting eye for detail.>>
11) After the front piece is bent, are there any special difficulties gluing on the top, back and bottom? 
<<Well, you want the thing to hold water... it's not as easy as it might seem.>> What order is best? 
<<Probably front to the back, and then that assembled piece to the bottom.>>
12) Have you heard of someone setting up a small shop to make acrylic aquariums? 
<<Uhh... Jason Kim of Aqua C comes to mind. He makes a fine line of protein skimmers, but also makes custom tanks and sumps. If I'm not mistaken, he started out as a one man operation. His skimmers are quite popular, and so he's not a one-man-show any more.>>
13) What fraction of aquariums sold in the US are acrylic now?
<<Couldn't tell you... but a quick mental survey says: depends where you live. If you live in an earthquake zone, you might not have a choice. Acrylic tanks are more expensive than their glass cousins so income plays a factor.>>
14) What is the difference in wholesale price of glass and acrylic aquariums in the US? What is the difference between the internet price and the wholesale price? 
<<I really don't have that information. You'd do best to ask the actual wholesalers and retailers.>>
14) What are the major advantages of acrylic? 
<<Two come to mind... acrylic is a better insulator. That and it is also much more clear than glass tanks which become more green as the glass gets thicker.>>
 Disadvantages? 
<<There are three disadvantages. One, price - acrylic tanks are much more expensive than glass tanks of the same size. Two, acrylic is easy to scratch and it's easy to do with a large chunk of live rock. This also means you need special cleaning pads. Third, and if you keep a reef tank, coralline algae has a strong attraction to plastics, acrylics included. This means that you either need to clean the viewing panels constantly, or go after them with special scrapers when you can't see the inhabitants any more like I do ;-) >>
15) Approximately how many manufacturers of 20-100 gal stock acrylic aquariums are there in the USA: 5, 10, 25? 
<<That's a good question, but I just don't know the market that well. I'd bet there are more than five, but not 25. Maybe more than 10 but not many more. Just a guess though.>>
16) Is it better to use a router, table saw or a panel saw to cut the acrylic?
<<A precision table saw with special blades for cuts. Router for cleaning the edges. Hope that helps. Cheers, J -- >>

Aquarium Frames
I was thinking about building a 20 gallon long aquarium to use as an Hospital/Quarantine tank. The only problem is I don't know where to find an aquarium frame for the tank.
<A frame...>
Would you happen to know where I could find one?
<Such plastic edging can sometimes be purchased from manufacturers like All Glass Aquarium, Oceanic... perhaps by way of your retailer...>
Are they required to have a tank like that? If not is there any other way I could put my hood on the top?
<Not required... by and large not functional... used more to put the glass, silicone together (like a jig)... you can build a system w/o such a frame, insert/silicone some glass strips to support a light unit. Bob Fenner>

I used the wrong Silicone sealant Hi Bob, I was just reading the articles on "One hundred percent Silicone... no mildewcides, other additives" under Building your own tanks, enclosed is a picture of the tank setup I made using 3/4 marine ply oak faced, then fiber glassed, epoxy painted and then I used silicone for Bath and Kitchen. <To just place the viewing panel?> It of coarse made me sick when I read the thread on mildewcides. My question is the equipment, base rock and live rock which was in this tank , I have the rock in a new tub with fresh saltwater "hoping" and the equipment has been clean completely What is your feeling on any of these items being reused in another tank ?? Thanks Tony <Mmm, should be fine. But I encourage you to cut away the exposed sealant and silicone over the old with 100% if/when you have all out of this aquarium. Bob Fenner>

Homemade Aquarium Supplies
Robert,
<Steven Pro answering today.>
I've been researching through the internet to find tips on do-it-yourself or make-it-yourself aquarium supplies, mainly to cut down the cost of some of the manufactured products like filter bags/cartridges, gravel/substrate, and decorations. I have lots of different types and sizes of filters (Marineland Penguins, AquaClears, Whispers and recently 2 canisters: a Fluval 303 and a Magnum 350), but I don't have any filter media or cartridges for them. I'm also pretty short on substrate material and decorations like rocks and wood. Do you have any recommendations for books or websites addressing make-it-at-home aquarium supplies and decorations?
<There are plenty of DIY sites, but those are usually about actually building something like a light, tank, sump, overflow, etc. not a filter cartridge. You are probably best of buying mail-order in bulk.>
Any advice on creating my own filter bags/cartridges/media?
<I have used polyester pads and other materials used for HVAC applications for prefilter material in aquarium trickle filters and pond filters.>
How can I get or make activated carbon in bulk?
<You can buy it many places, making it is a completely different thing. It is processed at extremely high temperatures and for part of the process in a vacuum, not something you could do in your kitchen.>
Can you offer any tips regarding gravel, rocks, wood, metals, etc. that are easily obtainable, cheap, and safe for fish?
<Metals are categorically bad. Many rocks and gravel contain metal as a contaminant. You will need to research the rock you want to use and identify their makeup to see if they are safe. You may also want to consider doing a bio-assay (as Bob says) and test the material in a tank with a few inexpensive fish.>
Thanks in advance for any help you can give.
<Your best bet is to look in the back of trade magazines for ads aimed at freshwater hobbyists with fish rooms, buying in bulk. -Steven Pro>

Can I build a 400 gal tank?
Hi, could I construct a glass aquarium 72in. by 36in, by 36in, according to garf.org's directions? << I believe you could. >> I really want to build a huge aquarium so that I wont have to pay as much for a manufactured one, and so that I can keep huge marine fish. On GARF's calculator on aquarium capacity, this size tank came out to be 404 gallons I think. Do you think building a tank this size according to their directions would break? << Well it all depends on glass size.  I would consult a glass shop before purchasing the glass, and get their input.  Obviously 1/4 glass would break, and 8 inch glass is way too big.  So the key is finding that intermediate. >> I want to set it on the carpet floor. Is this possible? << Yes, but I prefer to put large tanks right on carpet padding, not on the carpet. >> Would 2 400 watt metal halides hanging over the tank be enough lighting for live rock, and to light up the tank? << No way.  Not to me, it wouldn't.  I would have more like six 400 watt bulbs on a tank that size. >> Thanks, Adam
<<  Blundell  >>

Acrylic Wall Thickness for Large Tank 7/17/04
I am building a very large tank in the shape of an equilateral triangle.  The dimensions are 24 feet long by 8 feet to the point of the triangle by 4 feet high (or deep).  It will be placed on a strong 18 inch concrete floor.  I am guessing that 2" for the sides and 1 inch for the top and bottom should hold well but I am just basing that on my limited engineering experience.  Do you know how I could find out if these dimensions will be OK.  Can you recommend any structural engineers if I need one or is it not that complicated if I know how to figure it out.  Thanks Dimitrios
<Hi Dimitrios!  I hope when you say that you are building this tank, that you mean you are having it built.  This is not a DIY project!  I would begin by contacting some of the following:  A large public aquarium, Reynolds Polymer and San Diego Plastics.  I would consult a structural engineer about the floor.  A public aquarium should be able to direct you to large tank manufacturer (SD Plastics is one, but this project may be beyond even their capabilities).  Reynolds polymer makes very large, very thick acrylic material for public aquariums.  They can probably direct you to a manufacturer that deals in large display tanks.  There are wall thickness calculators on the 'net for acrylic tanks, but they only apply to rectangular tanks.  Good luck!  Adam>

Tip for checking for tempered glass
Hello all:
Reading the attached response I recalled a nice tip that I used when drilling my own glass aquarium.
You can easily identify whether a piece of glass has been tempered or not by using 2 polar lenses. I used a camera polar lens and a polarized lens from
a pair of cheap sunglasses.
Place a lens on each side of the glass and rotate one while looking through it. If the glass is tempered you will notice a distinctive pattern that
shows as you rotate the lens that was formed when the glass was tempered. If it isn't tempered, it will just look clear.   Try it out on
an automobile window that is marked as safety glass to see what the pattern is like that you are looking for. Works like a charm. On my 90 all glass,
none of the panels were tempered, I had the bottom drilled by a glass company for $10 / Hole.
The glass company was even unaware of this little trick.
Just thought I'd share.
Have  a good day!
Bill
<Thank you for this. Will post for all's edification. Bob Fenner>

Plywood tank
Hi guys..
<A.J.>
Thanks for putting your time and resources into the best aquatic information website ever...So many of my questions have been answered (some I didn't even know I had) by happily perusing the posts on your web site. I do have a question I could not find answered anywhere though...
<Okay>
I am planning on building a large plywood tank and do have some experience building them, as well as glass and acrylic tanks/sumps etc. I think I have looked at every plan available that I could and that find that many of them are structurally sound and tested methods. The main problem I see with building these tanks is of course sealing the non glass portion of these tanks. There are many methods the best I've used being several layers of epoxy or fiberglass resin, all of these work for sealing the wood but are very labor intensive.
<I've used a few methods with plywood constructed tanks... like wood-glue or such jointing of corners along with good metal screws, then pre-made rolls (usually four inches wide) resined into the inside joints...>
I had an idea, as yet untested that I thought I'd run by you. Basically it consists of structuring the plywood box with a glass front, but instead of sealing the inside with epoxy, line it with a 1/8 inch layer of acrylic or pvc. structurally this thin layer would do nothing. It is only to seal the wood. this would have the advantage of being easily drilled for overflow/bulkhead fittings. The obvious problem I see is what to do the actual sealing of the front glass to the acrylic sides and bottom. I don't think silicone will do the trick. Do you know of any kind of sealant product that will adhere to both glass and acrylic well enough to be used in this type of application?
<I don't... though if you use PVC sheet instead (cheaper, and just as strong, serviceable for what you have in mind here), there are reasonable "welding" options for making the "shell" within the plywood/structural box as you describe... BTW there have been a few companies that fabricated tanks in a similar fashion (Aqua Decor and their mainly "bubble" tanks, our old company's Nature Etc, Inc. spun polyethylene tanks within furniture stands... They can/do work>
Please tell me if you think this is impossible so I can get it out of my head, Thanks.
A.J. Ginther
<Look into the PVC sheeting possibility... a few folks use this material as a stand alone structural component (Quality Marine in Los Angeles most innovatively). Bob Fenner>

Re: Plywood tank
Thanks for the reply..
<Welcome>
Am I understanding this correctly? Are you suggesting I do the whole inside with pvc including the front piece, or are you saying I can adhere a front glass panel to the inner pvc panels somehow?
<The latter. The glass/viewing panel (acrylic if you want) can be nestled into a bead of silicone, against the PVC sheet, with the PVC sheet in turn being supported (all but the cut-out for the glass) by the structural frame>
I looked at clear pvc panels for the front and they are a little pricey for my needs. I already have the glass.
<Look at the opaque sheets... you don't need the clear... and shop around (maybe online) for larger distributors. They're much cheaper. Bob Fenner>
Thanks again
A.J. Ginther

Aquarium Sealant, Epoxy  9/29/05
I have a tube of DAP silicone that is rated as suitable for aquariums.  However, it says on the tube that it is only good for aquariums that are less than 18" deep and 35 gallons.
<An issue of implied liability limitation>
   My tank is considerably larger than that.    Who makes a silicone that is suitable for deeper tanks?  
<Nothing really>
  When one visits the shark tank at a public aquaria, the corners seem to be sealed with silicone.    Which brand?
<Brand is unimportant... 100% is 100%... I have used many different makers/licensers...>
Are fish and aluminum incompatible?  
<Mmm, not in all cases... with certain water quality, the presence of this metal can be quite toxic>
And if so, what kind of epoxy would be suitable to coat the aluminum?
Thomas W. Warner
<Mmm, those made for underwater use ("boat") that lack anti-fouling compounds. Bob Fenner>

Drilling an AGA follow up 10/7/04
Thanks for the response.  Is drilling the back of the tank something I can attempt, or is that best left to professionals?
<It is fairly simple to do if you have a drill press (possible, but not recommended with a hand drill).  Most of the professionals have tripod mounted drills that avoid the problem of the depth of the neck on a drill press.  Price this service against the price of a diamond edged hole saw for drilling glass, and you will find that it is often cheaper to pay someone else.>
Alternatively, I was thinking of upgrading to a 65 gal (36x18x24) which would fit my stand, with some modifications, and use the 40 gal (36x12x20) as a sump (plumbed thought the wall in my finished basement).  Any thoughts on that?  <Sounds like a nice plan.  Putting the sump in an basement or adjacent room cuts down on noise and often allows for much easier access.>
Also, you say that MH are not necessary...I know, but I love the aesthetics that they deliver over VHO, PC (fluorescence in general).  Kind of like a computer...what's a kick-@#$ computer if you're staring at a 15 in Kmart special monitor!<Too true!  I certainly wasn't knocking MH or recommending against their use (I use them), I have just seen way too many examples of folks that think they need 1.21 Gigawatts of light over their tanks!  If you like the "glimmer lines" or other aesthetics of MH, go for it!>
Although, someone from the LFS told me he didn't like MH because they Hum too loud (along with the sound from a couple of fans for cooling).  Then he says I'll need a chiller. That may be true, but the Chiller would be in the adjacent room anyway. <Most ballasts produce very little noise, and electronic ones are silent.  Super quite cooling fans can be had, and since you are plumbing through an adjacent wall anyway, you could put an exhaust fan in your "fish room".  If you have central AC and give some consideration to ventilating your hood, a chiller is not likely to be necessary.>
 Personally, I like the hum of POWER...just not TOO much sound! Just can't beat the shimmer MH produce and you must admit, most corals benefit from MH...or is that not true?
<Ahhh... the soothing sound of 60 cycles!  Some corals benefit from MH, some it doesn't matter and some may be harmed.  There is not lighting scheme (or any aspect of husbandry) that is ideal for all animals.  Be sure to acclimate low light corals to bright lights carefully.>
Any preferences on in-sump skimmers?
<Euro-reef, All-seas G series and Aqua-C all make very fine products.  Euro-reef (and the all-seas knock offs) are pricey, but keep in mind that they include a pump).>
Thanks for the advice. <Always a pleasure.