Coco and silica
We are using coco + perlite @ approximately 70/30. I have looked at and tried many silica products, including GH ASi. Most all of them use some combination of potassium silicate + silicate dioxide. To my understanding, these products are not readily available to the plant. Lets just not worry about how to apply them. These products are made so that they can be soluble and suspend for hydro application. Once they are in the medium, they eventually break down into monosilicic acid, which is now what the plant can absorb.
So here are the concerns or questions;
What breaks them down? How much time does this require? I've read that it can take weeks if not months for these products to be broken down into mono-silicic. I need them NOW in Veg through week 3 of bloom. In coco, which is hydro, everything eventually gets pushed out, probably within a week or 2. So it is possible that these products do not even have a chance to break down into something useable, before they are evicted. It would seem to me that the best option is to use a product already broken down into mono-silicic. Also, you need to apply this when the plants are young and growing. Another option would be to add vermiculite into the substrate mix. Other than the access to silica, this negates the advantages of coco coir and frequent fertigation. The only option I see working is to find and use a readily available mono-silicic acid product. Questions? Comments? So far, I cannot recommend any product based on K20 + Si02 and for hydro, the only logical choice is a product already as mono-silicic.
When I was looking for silica the local hydro store guy steered me to Cyco brand with the pitch being it was mono-silicic and plant available. Now I know grow store guys adhere to a strict honor code and would *never* bullshit anyone but that's how I got mine.
Looking online at Cyco website it doesn't specifically say its mono-silicic, in fact the Cyco page is about as bare bones as you can get. But some online grow store listings for the product do say that. This being one example, https://www.hydrotekhydroponics.com/cyco-silica-1000l-501099
Not being a chemist I have no way to verify where the truth lies.
Check out this Link. Si products like armor si have several different types of silcic acid when broken down with water. The percentage of plant available si may be low, but it still provides the plant with si.