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FAQs about Marine Substrates: Silicate Sands

Related Articles: Marine System Substrates (Gravels, Sands) by Bob Fenner, Marine Substrate Options by Sara Mavinkurve, Deep Sand Beds, Live Sand, Biofiltration, Denitrification, Live Sand, Live Rock, Biominerals in Seawater, Understanding Calcium & Alkalinity

Related FAQs: Marine Substrates 1, Marine Substrates 2, Marine Substrates 3, Marine Substrates 4, Marine Substrates 5, Marine Substrates 6, Marine Substrates 7, Marine Substrates 8, Marine Substrates 9, Rationale, Selection, Reef  Substrates, By Type: Aragonite/s, Coral Sands, Dolomites/TapAShell, Southdown & Such, Collecting Your Own, & Physical Make-up, Size/Grade, Location, Depth, Marine Substrate Cleaning 1, Marine Substrate Cleaning 2, Moving/Replacing/Adding To, Marine Substrate Moving/Replacing/Adding To 2, Substrate Anomalies/Trouble-Fixing,

Silicates are pretty much chemically inert (won't add Ca, Mg... or Alkalinity), and too smooth to host much in the way of microbes, a bit too sharp for some animals...

Florida Sand/Substrates 2/16/12
<Hello Braiden>
 I am new to starting an aquarium.  I am going with a 90 gallon reef ready with a 30 gallon sump.  I Googled and looked through many articles and found some stuff about Florida sand and somebody (Mike D I believe) asked if the person was from the Fort Walton Beach area.  That is where I am gathering my sand from and I would like to know if anyone knows what the composition of the sand is from that area.  Do you know if it is silicate based?
<The sand on the Emerald Coast beaches is comprised mainly of quartz washed down from the mountains by the Apalachicola River, 130 miles east of Ft. Walton Beach. It is this quartz, ground to a perfect oval in each grain of sand, that makes the beach "squeak" when you walk on it.>
I hear silicate sand is bad.  Do you think this sand would be ok to put in the aquarium after boiling it or another cleaning method if you have a recommendation?
<Silica sand will cause diatom blooms and is not recommended.  The quartz sand on your beach is actually silicon dioxide, a type of silicate.>
If you do know what the sand from that area is made of, what pros/cons would it have using it?
<For one, it has no buffering capability to help maintain pH and dKH.>
I was going to add a scoop or so of live sand from the LFS to get it going if that would help.  It is very white and very fine sand with a few tiny little black specs in it.
<Likely iron oxide.>
Also I was wondering if sand that fine would make my water look cloudy or if it would stay settled at the bottom with no problems.  Any advice would be greatly appreciated.
<I would use aragonite/crushed coral sand.>
Thank you.
<You're welcome.  James (Salty Dog)>

Which Sand? - 08/13/05 Hello Again, <<Greetings>> Your site has been the best thing for the hobbies since glass aquariums! <<Thank you>> My question: I will need aprox. 300LBS of sand for a 5" base, I wanted to put down the first few inches with Home Depot sand to save money, and then top off with live sand.  I cant find Sanddown <<Southdown?>> name by me.  But I have found "silica free" sand.  Is this ok? Thank-you in Advance as Always. Dan P <<Should be fine, silica-free or otherwise.  I have done this very thing with the refugium on my frag system.  EricR>>

Tahitian Moon Sand 8/5/04 Anthony, you are awesome as always. Thank you. <always welcome my friend> I have been totally unsuccessful at finding Southdown up here in the NH/MA area.  Maybe I'll look into this moon sand more. It's black and sure looks neat. Thank you... Part 2: I called CaribSea and asked about the Tahitian Moon Sand. It is silica based and not recommended by them for use in a DSB.   <silica sand is not harmful per se... just not helpful> Just thought I would pass the info on.   <yes... thanks kindly> They said that if you want a darker look you can use their Indo-Pacific which is a mixture of aragonite and volcanic materials.   <ironically... volcanic matter is far more risky than silica. DO stick with straight oolitic aragonite for best overall benefits/results> I'm sticking to the oolitic aragonite. :-) Wes <best regards, Anthony>

Silica based sand for marines? likely pass 5/5/04 thanks for all the help in the past <always welcome> I live in RI. I know that the beach sand here is full of silicates and possibly iron. would this be bad to use in a refugium. <perhaps... but worse still is the fact that there are millions of people living behind that coast to which everything runs (to the sea). Yikes! And beyond pollution, coastal waters are hot-spots for parasites and disease. (need 4 week QT bare minimum). Sure seems like a lot of risk and a lot of work. I'd advise against it> will the silicates feed diatoms in the main tank if I use the beach sand in the sump. <possibly> I hope to grow macros and mangroves in the sump and keep starfish and other inverts in the sump to eat up any detritus. if you have any thoughts on this, any help would be great. thanks <do spend the few dollars on a carbonate based sand. We have Aragonitic "Southdown" sand at so many of the N.E. Home Depot stores... $4 for 60 lb Anthony>

TAHITIAN MOON CAUTION. . . Hi gang: <Chuck> A reader queried about Tahitian Moon oolitic sand yesterday. . . Just a note of caution: In my experience (fortunately limited to a 12 gal. nanoreef) it looks incredible in bag at the LFS [beautiful jet black]. . . and incredibly AWFUL in the tank. Imagine buying a black car you could never really wash. This is worse. The upper layer goes murky gray. . . regardless of normal/frequent cleaning. Even worse, the 'optical illusion' seems to be the eye 'thinks' all the sand is the color of the grungy top layer. . . Call it a case of the beauty of theory hitting the mess of reality. I junked the stuff and started over. Chuck <Thank you for your input. Bob Fenner>

Silica and the use of it in aquariums 11/05/03  Hi there, my name is Mohammed.  <howdy>  I have had numerous discussions with friends and users on the WetWebMedia forum about sand and substrates, and my impression was always to stay away from silica sands. I am setting up my 80gal tank right now (curing rock at the moment) and I just received this article from a friend of mine and wanted to get your input on the matter. Thank you very much in advance Mohammed.  < I agree that silica sand compositionally poses little or no harm. The problem, rather seems to be that its angular shapes (in contrast to spherical oolitic matter) is somewhat more conducive to the settlement of diatoms. Anthony> 

Silica and the use of it in aquariums II 11/7/03  But the article does talk about diatoms and silica sands, and says that there is no obvious diatoms inhibitor shall we say in using silica over aragonite sands. And that is exactly what I wanted to get your input on!<I think one of us is missing the point here, my friend... not sure who though <G>. I am not commenting on the anecdotal concerns of silica sand as a source of elemental silica for the growth of diatoms (composed of silica), but rather that the structural shape of the grains (angular versus oolitic) is the reason for algae like diatoms to settle faster (more conducive on sharp sand)>  So is it or is it not (silica) a diatoms conductor?  <I believe the question is moot... neither. I say this because any minor favor of grain size to diatom growth is minutia compared to the much bigger issues of nutrient control in an organically rich aquarium. Again, it is moot because your/our aquarium husbandry including nutrient export processes (skimming, water changes, carbon/ozone, etc) should be easily good enough to handle any small disadvantage or not to using silica sand. I cannot be any clearer than that, mate. Use silica sand confidently if you like. Most folks will benefit from the more natural media of aragonite instead (shape and composition, buffering ability, etc)>  thank you Mohammed  <wishing you the best. Anthony> 

Silica and the use of it in aquariums III 11/11/03 Thank you very much for all your help. You are a greater resource. <always welcome, mate> Can I use the silica sand for a DSB? <yes... if you compensate otherwise in the system (dosing) for the lack of buffering/ALK support> I don't see why I wouldn't be able to, or why it would act any different than aragonite sand in a DSB, but I thought I should ask just to be in the safe side. <the aragonite is an excellent buffer and source of calcium... silica offers none> Also, Is there a link that you can refer me to for DSB's. I just needed to know how the DSB process works. thanks Mohammed. <please do a keyword search for "DSB" and "aragonite sand", etc on the Google search tool on our home page at wetwebmedia.com for many links to information on this topic. Anthony>

Silica in my puffer tank Hi ..I have a new Tank (4 weeks after maturing) and I have 3 puffers in there...before I knew any different I used tap water and that has resulted in horrible brown water ..I have since moved on to RO water .. although reassures it will not hurt my cherished puffers I wondered if there was anything we can do top speed up the process of getting rid of the silica ..we have a poly filter and have put carbon into the filter .. thanks a lot Steve <Mmm, there are a few things... some chemical filtrants, using other organisms to take up the silicate... but I would just wait... time and regular maintenance will resolve/solve this issue best. Bob Fenner>

Silicate based sand Robert, I'm looking into silicate based sands for my marine FOWLR tank. The only reason is that I can fill my 80 gallon long with 3 to 4 inches of sand for $5 versus the $200 for any of the local aragonite sand. Some people say this is fine. Others say it isn't. I realize that with silicate based sands I'd get no PH buffer and I could have a problem with nuisance algae. Then again, I've also read that the algae won't be any more of a problem than with aragonite sand. I can seed the sand with GARF grunge (I live about 5 miles from GARF so that's not an issue at all) but I'm curious to know if there is any reason silicate sand wouldn't make a good live sand bed. Any thoughts? I'll probably get the aragonite anyway, but I'm just really curious. <Please read here: http://www.wetwebmedia.com/marsubstr.htm  I would not use a silicate based substrate in nearly all types of marine set-ups... for the reasons you have listed above and others in the article cited. Bob Fenner> David Rencher

Re: Silicate based sand Oh, you mean I could have just read the website for the answer? DOH! How silly of me to forget. Thanks <Thank you my friend. Be chatting. Bob F>

Alternative sand substrate Hi Mr. Fenner, I've been reading in your daily FAQs, and older FAQs from lots of people that use the Southdown play sand from Home Depot. <Yes, a dear acquaintance is quite "buff" (she) from hefting several pallets about this far to the west (California)> Unfortunately, I live in Montreal, Canada, and we do not have that brand here. Although we do have the Home Depot store chain here. <Do make inquiries... if you can get a few pet-fish friends together, perhaps a whole pallet or two can be special ordered, shipped up> They do carry the line of different types of sand of another brand that is called Quikrete. I've looked at the sands, and while they do have what they call a common blend of sand that has a warning on the label that says it contains silica in it,  <It does, in high concentration> they have another blend that is labeled for sand-boxes that has been washed, cleaned, and dried, and does not say anything on the label about any silicates in it. Have you ever heard of this brand because the company is in the States?  <This natural product is not consistent... you can look with a magnifying glass, low powered microscope to easily assess how much silicate/sand is present... the shinier, flatter, smoother "poker-chip" like pieces...> Would the fact that nothing is on the label for the play box type about silicates make it safe enough to use in a reef-tank, or it means nothing, and I would be better off not chancing it?  <Worth investigating further. Please do post your query to our: http://talk.wetwebfotos.com/ and other bulletin board, chatforums in the hobby... some folks will certainly have recent personal experience here> I figured that if this sand is catered to sand-boxes, they would know enough not to make it health hazardous for the children that will be playing in it, since the silica is a known cancerous agent. <Umm, actually... most everything is a "cancerous agent" (in point of fact our bodies are quite cancerous... not a joke)... in quantity, type of exposure... In the grand scheme, scale of things, large particles of silicon dioxide (a very common, ubiquitous component of the surface of this planet) are relatively non-toxic> I would really like to find an alternative to buying something like the CaribSea brand because around here, the cheapest I've found for CaribSea is $32.00 for 15lbs., while the Quikrete brand for instance costs $4.95 for 50lbs. What a difference in price eh!!!! <I'll say! See my comments above...> I've also looked online at the CaribSea brand, and while it is cheaper a bit, once you add in shipping etc. it comes out to the same price. I just think it is crazy to pay that high price for sand, ( while the composition of the CaribSea brand might justify the high price, I would really prefer an alternative if it would do just as well, as this hobby is expensive enough!!). <Agreed... but not for the industrious! Bob Fenner> Thanks in advance, Greg N.

Sand: Aragonite vs. Silica I just setup my 65gal saltwater tank yesterday, planning for a reef setup. Nothing is in my tank but water and sand. The sand I bought was from Home Depot but it's not the Southdown sand like people have mentioned in your faq's. I tried looking for it in the garden section but I couldn't find it, so I bought 100 lbs of some other sand. What worries me is that it is silica based. I didn't notice this till everything was done. Is this going to cause me troubles with a reef setup, or should it be ok?   <I prefer and recommend aragonite sand because it does dissolve over time and add beneficial things (calcium, alkalinity, magnesium, etc.) to your water. Although, it has been thought by many (including myself) that with silica sand you may fuel diatoms, I no longer believe this to be the case. I have recently read some very convincing articles by Dr. Rob Toonen, Dr. Ron Shimek, and James Fatherree disputing this. So relax. Your silica sand will not dissolve and create a problem, though it will not have all the benefits of aragonite material.> Thanks, Jason
<You are welcome. -Steven Pro>

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