Grade of sodium silicate?
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Randy Holmes-Farley
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I use a technical grade. It should be OK since you dose so little. 
Randy Holmes-Farley
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I'd add about 1/3 of an mL once a week or two. You can also divide it into smaller, more frequent doses. That should spike the silica ti roughly 1 ppm, which is not unnaturally high for seawater, and then it will decline as things use it.
Here's a cut and paste from my article:
Based on my dosing experience, aquarists are probably safe dosing the equivalent of 17 uM (1 ppm SiO2) once every 1-2 weeks. That is based on the fact that my tank used that much in less than 4 days without having any sort of “bad” reaction. Of course, there’s nothing wrong with starting at a tenth of that and ramping up. And, of course, if you do get too much in the way of diatoms, just back off on the dosing. I presume that all that I added to my tank went into various organisms that us it (sponges, diatoms, etc), but perhaps I have more sponges than other aquarists, and diatoms consequently may be more of a concern in some tanks than in mine.
I’d also advise occasionally checking the soluble silica concentration in the water, in case the demand in your tank is substantially less than mine. If the concentration started to rise above 50 mM (3 ppm SiO2), even in the absence of diatoms, I’d probably reduce the dose rate because that is close to the maximum concentration that surface seawater ever attains.
Here’s how to determine dosing amounts. I’ll assume that you want 17 uM (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 17 uM (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.
Here's a cut and paste from my article:
Based on my dosing experience, aquarists are probably safe dosing the equivalent of 17 uM (1 ppm SiO2) once every 1-2 weeks. That is based on the fact that my tank used that much in less than 4 days without having any sort of “bad” reaction. Of course, there’s nothing wrong with starting at a tenth of that and ramping up. And, of course, if you do get too much in the way of diatoms, just back off on the dosing. I presume that all that I added to my tank went into various organisms that us it (sponges, diatoms, etc), but perhaps I have more sponges than other aquarists, and diatoms consequently may be more of a concern in some tanks than in mine.
I’d also advise occasionally checking the soluble silica concentration in the water, in case the demand in your tank is substantially less than mine. If the concentration started to rise above 50 mM (3 ppm SiO2), even in the absence of diatoms, I’d probably reduce the dose rate because that is close to the maximum concentration that surface seawater ever attains.
Here’s how to determine dosing amounts. I’ll assume that you want 17 uM (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 17 uM (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.
Randy Holmes-Farley
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Those may be harder to find, but would be fine. The amounts added of calcium or potassium will be small.
Randy Holmes-Farley
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I do not know on sponges eating diatoms, but they certainly may.
OP
OP
Well my logic is that extra sodium isnt being added. This way both calcium and potassium are consumed. Nothing extra added just any impurities.
OP
OP
Ive read that they filter water from .5-1 microns. And that they can replace a skimmer. I just got an orange ball sponge, thats all they had.
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I bought a yellow ball sponge several years ago from Liveaquaria Divers Den and it has grown nicely. I have it in a tunnel under a rock overhang and it is growing enough to reach the sides and top now.
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If it is not a photosynthetic type, dark is better to reduce altar growth on it.
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The logic of not adding sodium is correct, but of such small magnitude as to be unnoticed. Seawater is already more than 10,000 ppm sodium, and adding 1 ppm silicate adds less than 1 ppm sodium.
OP
OP
So if i add 1ppm per day of sodium silicate, my reef would add 365ppm of sodium in a year? Or a total as in your example, a total of 10,365ppm? And in 10 years of using non water changed water, 13,650 ppm sodium, since to my knowledge no organism extracts sodium from water at any appreiable amount it would likely increase. That could be a problematic increase or no?
OP
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Its so hard to find any of those chemicals. Even online. I found one place but they required a special account. So i couldnt buy it.
However i did find magnesium silicate. And its cheap. Would that disolve and work? Its talcum powder "extra pure". I asked the seller the purity well see if he knows.
However i did find magnesium silicate. And its cheap. Would that disolve and work? Its talcum powder "extra pure". I asked the seller the purity well see if he knows.
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I would not add 1 ppm silica daily. Once a week or two.
It adds less than 1 ppm sodium per ppm of silica. In fact, only 0.38 ppm. At once a week, that's only 20 ppm in a year. No one can measure their salinity close enough to know the difference between 10,700 and 10,720 ppm sodium.
Foods and additives add sodium, skimmers remove it, etc. There's a sodium balance in the tank that makes this a small component.
How are you supplying alkalinity? It might be a much bigger source of sodium.
OP
OP
Im using baking soda for alkalinity. Id like to use kalk but havent because i need to get a top off under my tiny stand lol. In fact i was worrying about the baking sodas sodium! Its lots?
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So baking soda is adding tons more sodium than the silicate. Maybe 100 times as much per day.
