Silicate Precipitate?

[cswanson]

Hi,

I want to dose silicate to encourage growth on a fan sponge I have.

I read this article:

http://www.advancedaquarist.com/2003/1/aafeature1

and found a solution of sodium silicate at a local ceramic supply store with this MSDS:

http://www.lagunaclay.com/msds/pdf/3rawmat/bliquid/mss.pdf.

When I add a drop of the solution to saltwater, a white precipitate is formed.

Will this dissolve?

Is it the magnesium hydroxide mentioned in the article?

I have a friend who is a chemist that guessed it might be a zeolyte.

I am concerned that the precipitate might be of silicate which might defeat my wanting to dose.

Anybody experience this before?

[bertoni]

I suspect you're seeing magnesium hydroxide, which precipitates temporarily. The high pH of the silicate solution causes it. You could try dosing a bit into a cup of water, and seeing whether the precipitate all redissolves, if you're worried.

[Randy Holmes-Farley]

It is normal for silicate dosing and I expect that it is magnesium hydroxide. :)