A chemistry question about silicates

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?

If brown algae feeds on silicates, wouldn’t it eventually eat through the glass walls of the aquarium and cause a leak?

Well, yeah.
How readily does silicone combine with other elements?

No. It’s going after the soluble silicates in the water, not the solid silica in the glass.

There is no silicone in your tank unless you’ve caulked it.

All of these compounds have wikipedia articles.

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.

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

Yes, I note the spelling, thanks. :slight_smile:

Are silicates sitting around waiting to mess with my aquarium?

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.

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.

Thanks, Bob.

Is uM thousandth of moles/liter?


m 10[sup]-3[/sup]
μ 10[sup]-6[/sup]

Thanks. I kept thinking, “Micro Meters?!?”

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.