pH down and potassium silicate, they went cloudy.

I grew a few organic plants in my closet and couldn't believe how thick the stems were. My coco plants get good bud but I always have to stake them up.

I decided to add potassium silicate to (hopefully) 100ppm of SiO2 during veg to make the stems stronger. After mixing my nutrients and bubbling for a day, the pH came out at about 7.0. I added some pH down to somewhere between pH 6.0 - 6.5 and the bucket went cloudy, and has remained cloudy for two days. This has happened before when using silicata in smaller amounts during flower as pH up. Back then, the cloudyness always went away when I added PK booster, but I'm hardly using any of that in veg these days. I can't really add more without throwing off my target macros.

The rest of the solution is a mix of a GH Micro clone, some Dyna Gro Grow, Epsom salts, malted barley, and tiny amounts of calmag and PK booster.

Is my plan to get strong stems through silica worthwhile? Is there any order I can mix this in to keep the cloudyness away?

Thanks for reading.

Are you adding the Silica first?

Are you adding the silica neat into the water?


try adding Silica first!


or if not first take what you want to add into your water and dilute it into a litre of water first etc and add that water silica solution into the water.

Silica went in first, then the other nutrients. The pH down went in 24 hours later, that's when it clouded up.

Forage said:

Silica went in first, then the other nutrients. The pH down went in 24 hours later, that's when it clouded up.

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What type of pH down?

Maybe the down is antagonising the silica.

try having a look on Google etc to see if you can find anything about antagonising between the acid for down and silica.

Also do you use the down neat or diluted?

I always make a dilution of my down 1:10 or 2:10 etc.

It's AN down. I dilute it to 20%, but that's because I don't know about chemistry and I'm afraid to handle undiluted pH down without goggles and gloves.

I just went downstairs and mixed a 1 liter test batch, starting with pH down, then the rest. It didn't cloud up. So now I suspect that either I bungled something during mixing, or the barley broke down and got cloudy (it was non-cloudy with sediment for the first few hours at least). I'll go ahead with a full batch and update in a day or two.

Forage said:

Silica went in first, then the other nutrients. The pH down went in 24 hours later, that's when it clouded up.

Click to expand...

Another thing with silica is to add it to your water and wait 15mins before doing any more nute additions.

I use armor si, added first, then jacks 321 and the use AN pH down. I only use 12 drops and I don’t get any cloudiness, so it can work at least in smaller amounts.

1 thought is silica precipitates out of solution at pH 3 and creates a white powdery effect. Maybe your adding the pH down too fast? I know how concentrated it is. If you add it fast it might create a local low pH effect and thus precipitates.

Hope you get it working because adding silica has made noticeable improvements. I also had the droopy stems in coco with chunky buds. I’m hoping this helps.

Hoverjet - A few other threads I read while I was tracking this down claimed that the cloudyness was calcium being precipitated out by the silica, I don't know enough to say if that's true or not.

It seems to be holding steady still, so I'm leaning even more towards some kind of operator error on my first bucket there.

I'm hoping silica is the magic bullet. My organic plants were grown under the same conditions, and had massive stems. Also everyone liked the bud. But it was smelly and messy and buggy and my closet was a swamp and the results were inconsistent. But I did replace half my bottle nutrients with seaweed extract on my last flower run and it went great.

It will clear, it just takes some time. Normally happens at res change when I haven't let the solution set. But my plants don't seem to mind.

I get some precipitations with Mega Crop 2 part at every res change. But I know the 5-12-26 has some impurities.

ive never gotten precipitation from adding silica last as a ph up. u got a video of it happening?

from my experience potassium silicate is overrated. i just use it as a ph up instead of actual ph up. if it does help even a little... great. if it doesnt... doesnt really hurt my pocket too much using it as a ph up instead of potassium hydroxide

Waay to much silicate. Try for 5 to 10 ppm.

cannabineer said:

Waay to much silicate. Try for 5 to 10 ppm.

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More like 30-50ppm. I use about 30ppm throughout the cycle.

Some techno info in silica and precip.

Forage said:

It's AN down. I dilute it to 20%, but that's because I don't know about chemistry and I'm afraid to handle undiluted pH down without goggles and gloves.

I just went downstairs and mixed a 1 liter test batch, starting with pH down, then the rest. It didn't cloud up. So now I suspect that either I bungled something during mixing, or the barley broke down and got cloudy (it was non-cloudy with sediment for the first few hours at least). I'll go ahead with a full batch and update in a day or two.

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The cloudyness is caused by nutrient locked out possibly due to unstable pH.
Silica normally has a high pH (the one I use is potassium silicate, about 12+ pH), mixing Silica with a nutrient that has a low pH will cause lockout (T.A. TriPart® pH is 5.8 Micro , 4.2 Grow and 4.5 Bloom).
The way I deal with it is adding Silica in first, then adding in the other nutrients one by one, mixing and waiting after each one for the pH to Balance out a bit in the entire mixture.
If using Cal/Mag - I would add that first (the Cal/mag i have is pH 6) then adding the silica (diluted) and then the rest.

IMO adding everything in slowly helps alot as the pH value will change slowly as oppose to drastically.

newbplantgrower420 said:

ive never gotten precipitation from adding silica last as a pH up. u got a video of it happening?

from my experience potassium silicate is overrated. i just use it as a pH up instead of actual pH up. if it does help even a little... great. if it doesn't doesnt really hurt my pocket too much using it as a pH up instead of potassium hydroxide

Click to expand...

I have used it as a pH up (since I don't have pH up), because of the High pH you don't have to add alot of Potassium Silicate to get it up , therefore not coming close to the recommended max dosage (2ml/5ltrs /1.3gal). When I started using Silica the plant looked and felt almost like it was covered in a thin plastic like a clear bra or a laminated document. I started using it in hopes of protecting the plant as it helps with heat resistance.

Hoverjet said:

Hope you get it working because adding silica has made noticeable improvements.

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Does it ever! I'm running 100ppm Si02 (I got to that number with a few assumptions) and my stems are comparable to what I was getting running proper organic in dirt. It's a dramatic difference. I'll probably cut it at the end of the stretch.

I'm not seeing any deficiencies, which is good. I've bumped up my organic content so much lately that I wouldn't notice cloudyness at this point anyways.

Don't assume, it's not hard to calculate elemental ppm.

Armor Si 10% Si02
Using 1ml/gal = 26ppm Si

Billy the Mountain said:

Don't assume, it's not hard to calculate elemental ppm.

Armor Si 10% Si02
Using 1ml/gal = 26ppm Si

Click to expand...

I'm using Cannamax labs potassium silicate with unlisted concentration. I couldn't find anything reliable online but I looked at the SDS and it seemed to match the specific gravity of Agsil21. I'm not 100% sure though, so I'm putting a little * beside those numbers.

I use a scale and measure my nutes in grams/10liters. It makes the multiplying straightforward.

Billy the Mountain said:

Don't assume, it's not hard to calculate elemental ppm.

Armor Si 10% Si02
Using 1ml/gal = 26ppm Si

Click to expand...

Your calculation is actually this:

1 ml ÷ 3785.41 ml (1 US gal) x 100 = 0.0264%
0.0264% x 10,000 = 264 ppm

10x more than you think.
Also, when you say "elemental", SiO₂ is actually a compound of which Si makes up 46.75% of SiO₂.

The instructions on the label state 1 tsp per gal = 1 ml per litre (0.1%)
However, 1 US tsp = exactly 4.92892159375 ml
Divide that by 1 US gal (exactly 3.785411784 litres)
Times the result by 100 = 0.13%

0.13% is 30% greater than 0.1%

So the instructions are a little inaccurate in what they state.

dand83 said:

Your calculation is actually this:

1 ml ÷ 3785.41 ml (1 US gal) x 100 = 0.0264%
0.0264% x 10,000 = 264 ppm

10x more than you think.
Also, when you say "elemental", SiO₂ is actually a compound of which Si makes up 46.75% of SiO₂.

The instructions on the label state 1 tsp per gal = 1 ml per litre (0.1%)
However, 1 US tsp = exactly 4.92892159375 ml
Divide that by 1 US gal (exactly 3.785411784 litres)
Times the result by 100 = 0.13%

0.13% is 30% greater than 0.1%

So the instructions are a little inaccurate in what they state.

Click to expand...

No, I don't think there's 264 ppm SiO2 at 1ml/gal ArmorSi

1000mg / 3.785 = 264.2 ppm * 10%(SiO2) = 26.4 ppm SiO2

I did neglect to account for specific gravity previously since Armour Si is a liquid (1.05kg/946ml)

26.4 * 1.1 = 29 ppm Si02


The general formula is: Labeled % * 264.2 * sg (if applicable) * grams