Sodium silicate

Cory · Jan 26, 2016

Finally i got some some sodium silicate.

But how much should i dose? 28 gallons total.

This one:
http://www.sciencecompany.com/Sodium-Silicate-Solution-16oz-P6375.aspx

JimWelsh · Jan 26, 2016

"How much" in order to achieve what goal?

The link says that the product is 28% by weight of silica (SiO2). It also says that it has a "specific gravity" of "1.39 g/cm3" (which sounds more like a density than a specific gravity to me, since specific gravity is a ratio, and therefore, unitless). Treating the "1.39" as a density, and using the percentage of silica stated on the label, then 1 ml of this solution will provide 0.28 * 1.39 = 0.389 grams, or 389 mg, of silica (SiO2). If added to 100 gallons of tank water, that 1 mL of solution would give a concentration of 389 / (100 * 3.785) = 1.03 mg/L = 1.03 PPM (w/v). To convert that to silicon, then multiply by the atomic weight of silicon (Si) divided by the molecular weight of silica (SiO2) = 1.03 * 28.085 / 60.08 = 0.481 PPM Si. In your case of a 28 gallon tank, then it would be 0.481 / 0.28 = 1.72 PPM, if you add 1 mL of this solution to your 28 gallons of water.

How much to dose depends upon how much you want to add.

EDIT: This stuff is quite concentrated. Be careful with it.

biom · Jan 26, 2016

Hmmm, why you multiplying by density? It is already in weight percentage.

My calculations are quite simple: 37 grams Na2Si3O7 in 100 ml of product =>12.9 grams Si in 100 ml =>129 mg Si/ml, and since Cory's tank is about 100 liters => 129/106=1.22, i.e 1.22 mg/l Si, if 1 ml of product is dosed.

Randy Holmes-Farley · Jan 26, 2016

These are my dosing suggestions:

Feature Article: Silica In Reef Aquariums ? Advanced Aquarist | Aquarist Magazine and Blog

Here’s how to determine dosing amounts. I’ll assume that you want 1 ppm SiO2 dosing, and you can scale from there. If the concentration of the supplement is 29% silica by weight (41° Baume), then it is 290,000 ppm silica. To get to 1 ppm silica, you then need to dilute by 290,000 fold. If you add 1.3 grams of this supplement (0.96 mL) to a tank with 100 gallons (378,500 mL), then the final concentration will be about 1 ppm SiO2. I’d disperse the concentrated silicate solution into some fresh water before adding it to the tank, and then add it to a high flow area. Because the pH is high, you likely will see some cloudiness that is mostly magnesium hydroxide. The magnesium hydroxide will dissolve without a problem, but to be safe, add the supplement in a high flow area.

biom · Jan 26, 2016

Arghh, got it, it is in weight %, not weight /volume % . I should read more carefully before starting calculations.

Cory · Jan 26, 2016

Thanks guys! I dosed .5ml so i guess i should be around.85ppm. Well see if my sponge grows.

So 2ml in 100 gallons = .962 ppm silicate. Or basically 2ml of this is 1ppm silicate per 100 gallons.

Cory · Mar 29, 2021

Im curious is it possible to purify sodium silicate at home? Im curious if this technical grade has some bad impurities in it so I want to purify it.

I was thinking if boiling it to remove the water, then add ro/di to the dry powder. Boil it down again but leave 20% of the water then drain it off to purify it. Would this work?

Randy Holmes-Farley · Mar 30, 2021

Cory said:
Im curious is it possible to purify sodium silicate at home? Im curious if this technical grade has some bad impurities in it so I want to purify it.

I was thinking if boiling it to remove the water, then add ro/di to the dry powder. Boil it down again but leave 20% of the water then drain it off to purify it. Would this work?

I cannot see a useful way to purify it.

I never worried about technical grade because the amount added was pretty low, and there are not (or at least were not last I looked) a lot better choices available.

Cory · Mar 30, 2021

Randy Holmes-Farley said:
I cannot see a useful way to purify it.

I never worried about technical grade because the amount added was pretty low, and there are not (or at least were not last I looked) a lot better choices available.

Okay that makes sense. Lasse had sent me this what do you think?

Sodium Silicate

Sodium Silicate | Na2O3Si | CID 23266 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological activities, safety/hazards/toxicity information, supplier lists, and more.

pubchem.ncbi.nlm.nih.gov

Sodium silicate

Impurities

Help

Range of trace impurities in typical sodium silicate solutions (3.3 silicon dioxide:sodiun oxide) fluoride, 6.7-9.5 ppm; chloride, 130-1900 ppm; sulfate, < 160-1,700 ppm; nitrogen, 0.1-44 ppm; arsenic, < 1-< 1 ppm; mercury, < 0.26-2.5 ppb; lead, 0.17-0.60 ppm; cadmium, < 10-21 ppm; iron, 36-120 ppm; magnesium, 4-26 ppm; calcium, < 1-76 ppm; aluminum, 50-220 ppm; phosphorus, < 18-< 18 ppm; vanadium, < 0.3-0.8 ppm; chromium, < 0.3-1.0 ppm;; nickel, < 0.3-< 0.3 ppm; cobalt, < 0.3-< 0.3 ppm; zinc, < 0.6-2.8 ppm; copper, < 0.6-1.1 ppm; bismuth, < 25-< 25 ppm; strontium, < 0.2-1.5 ppm; barium, < 0.2-2.8 ppm; manganese, 0.1-1.8 ppm; tin, < 60-< 60 ppm; antimony, < 15-< 15 ppm; selenium< 20-< 20 ppm. /From table/

Randy Holmes-Farley · Mar 30, 2021

I'm not concerned.

If you dose 1.3 grams (1 mL) to 100 gallons, you will boost SiO2 to about 1 ppm SiO2.

That is dilution by a factor of 378,000 (1 mL per 100 gallons).

So every impurity concentration drops by a factor of 378,000 to give the final concentration in the tank...

Fluoride 10 ppm --> 0.000026 ppm
mercury 2.5 ppb --> 0.000007 ppb
lead 0.6 ppm ---> 0.000002 ppm
etc.

Cory · Mar 30, 2021

Do you know if that analysis would be for sodium silicate powder, or also the water added to it to make it water glass?

It seems those impurities would even act as trace elements and possibly be a benefit. Lol

Randy Holmes-Farley · Mar 30, 2021

Cory said:
Do you know if that analysis would be for sodium silicate powder, or also the water added to it to make it water glass?

It seems those impurities would even act as trace elements and possibly be a benefit. Lol

No, I don't, and yes, they would.

Cory · Mar 30, 2021

Would it be bad to dose 1ml per day without testing? I have a salifert test kit for silicate but it never reads anything for silicate even after dosing a half hour later.

Randy Holmes-Farley · Mar 30, 2021

Cory said:
Would it be bad to dose 1ml per day without testing? I have a salifert test kit for silicate but it never reads anything for silicate even after dosing a half hour later.

In what size tank?