# A chemistry question about silicates **URL:** \ **Category:** Factual Questions\ **Created:** [March 30, 2016, 1:41am UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595 "2016-03-30T01:41:01Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [March 30, 2016, 1:41am UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/1 "2016-03-30T01:41:01Z")
Silicates are blamed for many things in the marine aquarium. I just read, “Brown algae feeds on silicates!” on a web site. Admonitions abound against using normal sand instead of sand composed of dead coral. I don’t know of silicone combining with other elements. Is the silicone in sand lying in wait to pounce on some other element or a compound and wreak havoc in my aquarium? ---
**Author:** ![boffking](https://avatars.discourse-cdn.com/v4/letter/b/858c86/32.png) [@boffking](https://boards.straightdope.com/u/boffking)\ **Post date:** [March 30, 2016, 2:20am UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/2 "2016-03-30T02:20:33Z")
If brown algae feeds on silicates, wouldn’t it eventually eat through the glass walls of the aquarium and cause a leak? ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [March 30, 2016, 2:41am UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/3 "2016-03-30T02:41:48Z")
Well, yeah. How readily does silicone combine with other elements? ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [March 30, 2016, 2:52am UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/4 "2016-03-30T02:52:52Z")
> [@boffking](#): > > If brown algae feeds on silicates, wouldn’t it eventually eat through the glass walls of the aquarium and cause a leak? No. It’s going after the soluble silic **ates** in the water, not the solid silic **a** in the glass. > [@carnivorousplant](#): > > Well, yeah. > How readily does silicone combine with other elements? There is no silic **one** in your tank unless you’ve caulked it. All of these compounds have wikipedia articles. ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [March 30, 2016, 2:54am UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/5 "2016-03-30T02:54:59Z")
Silicone is the synthetic compound used in, e.g., breast implants. It could also be used as a sealant, possibly even in aquariums, in the form of silicone rubber. The element silicon (note the spelling!) naturally combines with many other elements such as oxygen to form silicon dioxide SiO[sub]2[/sub] also known as silica. One can use silica as precursor to make glass, possibly for even for the aforementioned aquarium. Silicon and oxygen could also be polymerized to make silicone (note the spelling!), previously discussed. Silicates are compounds of silicon and (usually) oxygen. Most of the earth’s crust is made up of silicates. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [March 30, 2016, 2:57am UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/6 "2016-03-30T02:57:31Z")
> [@Ruken](#): > > There is no silic **one** in your tank unless you’ve caulked it. I don’t actually know if that’s true, not knowing much about aquarium chemistry. Silicon is the element. Silicone is a siloxane polymer Silica is the main component of sand and glass Silicate is an anion that may be part of a soluble compound ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [March 30, 2016, 2:59am UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/7 "2016-03-30T02:59:33Z")
Yes, I note the spelling, thanks. 🙂 Are silicates sitting around waiting to mess with my aquarium? ---
**Author:** ![Ornery\_Bob](https://avatars.discourse-cdn.com/v4/letter/o/da6949/32.png) [@Ornery\_Bob](https://boards.straightdope.com/u/Ornery_Bob)\ **Post date:** [March 30, 2016, 3:01am UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/8 "2016-03-30T03:01:39Z")
> [@boffking](#): > > If brown algae feeds on silicates, wouldn’t it eventually eat through the glass walls of the aquarium and cause a leak? No, we’re talking about silicates dissolved in water and the algae doesn’t actually feed on the silicates, it uses the silicon the same way we use calcium. As for the OP, it’s silicon, not silicone, that we’re concerned with. Silicon is an element (and mineral) but silicone is an adhesive. The silicon in silicone doesn’t leach. As for the actual question, I would recommend starting with: [Silica In Reef Aquariums - By Randy Holmes-farley, Ph.D.](http://www.advancedaquarist.com/2003/1/aafeature1) Silicates in the marine environment is a complex subject and while silica sand can release significant amounts of silica, it’s not unusual for reef tanks to rapidly use up soluble silica. Read the Randy Holmes article - he knows what he’s talking about and doesn’t shortcut. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [March 30, 2016, 12:23pm UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/9 "2016-03-30T12:23:30Z")
Thanks, Bob. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [March 30, 2016, 3:04pm UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/10 "2016-03-30T15:04:17Z")
> [@Ornery\_Bob](#): > > As for the actual question, I would recommend starting with: > > [Silica In Reef Aquariums - By Randy Holmes-farley, Ph.D.](http://www.advancedaquarist.com/2003/1/aafeature1) Is uM thousandth of moles/liter? ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [March 30, 2016, 3:46pm UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/11 "2016-03-30T15:46:46Z")
> [@carnivorousplant](#): > > Is uM thousandth of moles/liter? Millionth. m 10[sup]-3[/sup] μ 10[sup]-6[/sup] > **[Metric prefix](https://en.wikipedia.org/wiki/Metric_prefix)** > > A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or submultiple of the unit. All metric prefixes used today are decadic. Each prefix has a unique symbol that is prepended to any unit symbol. The prefix kilo-, for example, may be added to gram to indicate multiplication by one thousand: one kilogram is equal to one thousand grams. The prefix milli-, likewise, may be added to metre to indicate division by one thousand; one millimetre is equal to one th... ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [March 30, 2016, 4:42pm UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/12 "2016-03-30T16:42:15Z")
Thanks. I kept thinking, “Micro Meters?!?” ---
**Author:** ![Arkcon](https://avatars.discourse-cdn.com/v4/letter/a/96bed5/32.png) [@Arkcon](https://boards.straightdope.com/u/Arkcon)\ **Post date:** [March 30, 2016, 8:14pm UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/13 "2016-03-30T20:14:40Z")
> [@carnivorousplant](#): > > Admonitions abound against using normal sand instead of sand composed of dead coral. So calcium carbonate instead of silica sand. OK. But do the same sources specify what I’d usually heard, that aquarium decorations shouldn’t be calcite rocks, or sea shells, because the calcium carbonate is soluble, and will alter the aquarium’s pH? Because that’s a thing that they should explain. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [March 30, 2016, 8:24pm UTC](https://boards.straightdope.com/t/a-chemistry-question-about-silicates/750595/14 "2016-03-30T20:24:56Z")
> [@Arkcon](#): > > So calcium carbonate instead of silica sand. OK. But do the same sources specify what I’d usually heard, that aquarium decorations shouldn’t be calcite rocks, or sea shells, because the calcium carbonate is soluble, and will alter the aquarium’s pH? Because that’s a thing that they should explain. One of the reasons for using calcium carbonate sand in the marine aquarium is to buffer the pH. I never use shells in a freshwater tank, save for Tanganyikas, again to keep the pH up.