You don’t have to use glycerol. You can use PG instead. Just add the same amount as PG, replacing glycerol 1:1. But as I noted, there are likely benefits to using glycerol, or a glycerol:PG mix; the only negative to using glycerol would be slightly reduced stability (which is made up for by using more cartinine and glycerol).
I’m still working on the 8% in a user-friendly method. The problem is at 8% we have much less water in solution, so creating a potassium silicate stock is more troublesome (AgSil 16H can be dissolved at 1:1 w/w ratio with water).
I’ll try to keep up with any new questions as I have time this week.
@AgTonik I’ve been using power si, but I bought this to try https://www.grotek.com/product-page/gro-silic
Now with my power si it would drop my ph super low and even more when using potassium silicate it would drive it way up.
Now with this grosilic it bumped my ph up by only .4 then when I added the agt50 it dropped it right back where it started.
Doesn’t mono silic acid usually drop ph?
Short answer- I don’t know. I think concentration and binder choice have something to do with what the pH can be in the final product. I remember seeing something on Sci Hub, but that’s going to take some digging.
Plants use orthosilicic acid (OSA, aka monosilicic acid). There are other species (forms) of silicate (like orthosilicate) which occur at various pH values, temperatures, and concentrations. Plants don’t use those other forms of silicate.
Silicon dioxide is the raw material used to create silicate products, but it’s very insoluble in water. To increase its solubility, it’s typically combined with a strong base (like potassium or sodium hydroxide), creating potassium silicate or sodium silicate salts. When these basic silicate salts are added to water, they increase pH due to the dissociation of the base (KOH or NaOH). In other words, when adding AgSil 16H to water, the potassium hydroxide used to make the silicon dioxide soluble affects the pH of the water (increasing it), leaving the orthosilicate (no longer silicon dioxide) in solution.
OSA is formed after a solution of orthosiliciate is acidified. OSA only exists at lower pH, forming around < pH 7ish. Recalling that the ionic silicate species at higher pH is typically orthosilicate.
Stabilized OSA products (like Power Si) must be fairly acidic (pH ~2-3) due to silicate chemistry necessary to complex OSA with the stabilizer (most commonly chloine).
While soluble silicate salt (like AgSIli 16H) are fairly basic due to the hydroxide used to make the salt (as described above). And aqueous orthosilicate products (like AgSil 21 and AgSil 25) are strongly basic (with extra hydroxide added to the solution) to increase solubility of orthosilciate and stabilize it, preventing other species from forming or the orthosilicate from polymerizing.
So, the reason Power Si drops pH is because it’s OSA which has been stabilized (meaning, it’s acidic). While potassium silicate (like AgSil 16H), or liquid silicate ‘water glass’ (like AgSil 21 or 25), increase pH.
Therefore, a quick and dirty way to tell what species of silicate comprises a product is to add said product to distilled or deionized water, and measure the pH. If it drops, the product is OSA. If it increases, the product is orthosilicate.
Now, to your question about Gro-Silic and why it increases, not decreases, pH. The answer is clear: it’s not an orthosilicic acid product, it’s a orthosilicate product. That fact is even more evident when we look at their claims, where they never mention the phrase “stabilized monosilicic acid,” and more so after reading the SDS, which states its comprised of silicic acid, as silicic acid hydrate (CAS 1343-98-2), not orthosilicic acid, and the pH is 11.5.
GroTek’s bullshit and lies below are astounding, and their lawyers are assholes for dancing around label laws. IMO they could be sued over #5 & 6 (class action anyone?):
They add boron, which is often added to stabilized OSA, making a casual observer think it’s stabilized OSA.
They use silicic acid hydrate as the silicate source instead of potassium or sodium silicate, making the casual observer think it’s orthosilicic acid. But they don’t mention that silicic acid hydrate is SiO2•xH2O (hydrated silicon dioxide powder), meaning they had to add KOH or NaOH to basify the water to make the silicic acid hydrate water soluble.
They market the product like it’s OSA (similar to Power Si)
They charge a very high cost for something which shouldn’t cost more than $20 per liter (like AgSil 25).
They don’t mention in the SDS that they’re adding considerable hydroxide.
They imply the bottle is comprised on “monosilicic acid” on their website, without actually making a factual claim that the bottle contains monosilicic acid. As evidenced in the very first sentence of the product page:
Grotek Gro-Silic™ is a concentrated liquid silicon supplement suitable for soilless and hydroponic systems
TL;DR: Fuck GroTek and their little games…and make OSA yourself instead of buying it and hoping you’re getting what they claim you’re getting.
Because Gro-Silicic isn’t stabilized OSA (or OSA at all), it’s just orthosilicate (‘water glass’). I assume they are accounting for the loss of some silicate after it converts to OSA in an acidic nutrient solution (because it’s not stabilized OSA), and because stabilized OSA seems to be effective at a lower concentration.
LOL, yes . But at maybe 1,000 times the cost of AgSil 16H if it was added in the same concentration to a bottle of water. And I would bet AgSil 16H would give a better final product because the SiO2:K2O ratio is probably higher with AgSil16H.
I hope someone calls GroTek our for this BS . Heck, send them a link to my post
If you want to use a next generation stabilized OSA for cheap, that’s considerably better than Power SI, Fasilitor, et al., albeit with a lower concentration of OSA, follow my SOP for a 4% stabilized OSA (H4SiO4) solution using AgSil 16H, L-carnitine HCl, 85% phosphoric acid, and glycerol (or PG, or PG + glycerol). I’m sharing a professional SOP once I have time to write it, after I finish testing a 6% and 8% stabilized orthosilicic acid formulation.
Here’s my stabilized OSA after a simple filtration through a coffee filter: clear and ready to use!
Have you guys tried my SOP yet?
The side-product salt from the previous pics was granular when rubbed between my fingers. I’ll send this out for a COA on the silicate concentration in the next couple of weeks.
@Flowerman you seem very well versed in the chemistry of silicates. Would you be willing to take a guess at what percentage of silicate from a potassium silicate product exists as silicic acid species at say 4.0-4.5ph in a nutrient solution? If it matters, the acids in said solution are acetic, citric and phosphoric. Concentrations of elemental si range from 20-40ppm. At least some of the silicate species should become silicic acid species at ph that low if I understand the chemistry correctly.
Steve was unsure of the answer when I called him. He asked me to email him the question so he can run it by Hugh Rodrigues. I’m also going to run the question by Dr. Daniel Fernandez.
In pure water without acids (excluding carbonic acid), greater than about 80% of the silicon (Si) from potassium silicate (like AgSil 16H) should be in the form of othrosilicate (at the working range you posted). Based on the fact the silicon in potassium silicate like AgSil 16H has a SiO2:K2O ratio of 1:1.6, with higher solubility than sodium silicate at a 1:2 ratio of SiO2:Na2O:
Once acidified, I would estimate greater than 90% of the orthosilicate converts to orthosilicic acid. So, overall, for a ballpark answer to your question, I’d guess greater than 70%. However, that figure could be lower considering you’re using organic acids rather than solely using mineral acids. And that’s assuming the calcium concentration isn’t too great to affect silicon solubility.
I will have data to share once I send in samples of my stabilized orthosilicic acid solution to be tested by Thorton Labs. Comparing thier quantifiaction of orthosilicic acid in solution to my calculation of 4% and 6% orthosilicic acid (assuming 100% of the silciate from AgSil 16H becomes orthosilicate into orthosilicic acid). The test is $85 and takes five days, so I should have data to share the week after next.
. But at maybe 1,000 times the cost of AgSil 16H if it was added in the same concentration to a bottle of water. And I would bet AgSil 16H would give a better final product because the SiO2:K2O ratio is probably higher with AgSil16H.
. Heck, send them a link to my post 
