Question about silica additive

I was recently cleaning out my nute cupboard and found a product called "PyroClay3". The description says

-"A natural source of mono & ortho sillicic acid. monosilicate and orthosilicate. Food for beneficial bacteria-

This got me curious, one because I have no recollection of buying this (must have been years ago and blazed), two because I've never used a silica additive. So after a few hours of reading I really want to try this stuff out, but have one problem. I can't figure out for the life of me how much to use.

I am running a homemade ebb&grow system w/ 15 3 ft tall plants in rockwool and a 17 gallon resevoir. Nutes- Cutting Edge Solutions 3 part @ 60% strength, Floralicious Plus Organic Enhancer 100%.
Watering once a day for 10 minutes. 32 days into flower.

On the back the instructions say -
Recycling systems: Add 2.5 grams per liter of resevoir volume to resevoir bi-weekly. Now with a 17 gallon resevoir, that comes to about 160g every 3.5 days. Considering this container I have in front of me holds 400g total and costs 17 dollars, I'm thinking that maybe I'm misinterpreting the directions here.

Does anyone here have experience with this product? I would love to test out an additive like this but need some advice before I go dumping stuff into my res. Thanks in advance.

The silica has to be in a soluble form. Yours is not readily water soluble but is basically silica clay/silt.

So even though it says I can add it to my resevoir, I can't?

Add it to some water pH balanced to the same pH as your reservoir. If it dissolves it is usable. If it does not dissolve it is not usable. Even if it dissolves you need to add it in small doses not all at once.

It is water soluble. I was hoping someone here could help me out with how much to use?