Does reducing phosphate reduce silica?

[Pete Hammersley]

I’ve heard a few youtubers (not always the most reliable source of info) say in a flash that GFO reduces silica, but with no explanation how? Is this true? And if so, I’d love to understand it better if someone could please explaine? I don’t like to just have the answer given to me, I need to get my head around the how and the why.

I have what is some form of Diatoms and wanted to reduce the problem.

Thanks in advance.

 

[reefluvrr]

I do not know if GFO removes silicates, but I have used Phosguard and it removes silicates.
I have tested my water with Triton. Sure enough silicates were reduced. Be aware though, aluminum levels was riased though. I did not see any adverse effect in my tank though. HTH

 

[Randy Holmes-Farley Verified Community Expert]

Yes, GFO can bind silicate. Silicate binds to the iron surface forming iron silicate structures, just like phosphate forms iron phosphate.

https://pubs.acs.org/doi/10.1021/es010996t

Modeling Silica Sorption to Iron Hydroxide

Abstract
Experiments were conducted to investigate the fundamentals of silica sorption onto preformed ferric hydroxide at pH 5.0−9.5 and silica concentrations of 0−200 mg/L as SiO2. At all pHs studied, sorption densities exceeding monolayer sorption were observed at silica levels typical of natural waters. Under some circumstances, sorption equaled or exceeded a monolayer while the particle zeta potential remained positive, a phenomenon that is completely inconsistent with available surface complexation models. To address this deficiency, an extended surface complexation model was formulated in which soluble dimeric silica (i.e., Si2O2(OH)5-) sorbs directly to iron surface sites. This new model fit sorption density data up to 0.40 mol SiO2/mol Fe and accurately predicted trends in zeta potential and observed H+ release during silica sorption to ferric hydroxide.