NPK - Factoring Silica & pH Down

Hi folks,

I've found myself getting really geeky about nutrition. I grow in DWC and have been through swathes of different nutrients and additives, building a library of what works and what doesn't for me. One thing I've realised is that adding pH Down (phosphoric acid), and Liquid Silicon (Potassium Phosphate) will undoubtedly have an impact on final NPK ratios.

I'm struggling to find information on how much these additives impact ratios. Liquid Silicon is 6% potassium silicate in solution; Growth Technology pH Down is 81-85% phosphoric acid. To my understanding, 100% phosphoric acid contains around 23.7% elemental phosphorous. So if my math is right, this means pH down represents NPK 0-0-0.19... does that sound right? And if so, is it even worth worrying about?

I've tried calculating multiple ratios of Micro/Grow/Bloom and every permutation leave me slightly short of potassium (in veg). I'm only adding silica at around 30ppm, so I don't see this as anything other than beneficial. In my grows I almost always find pH rising (between half a point to a point every couple days) so I see pH down as an incremental challenge.

Am I overthinking things here? Or are there other geeks who have also pondered this question? Am keen to get people's thoughts.

Thanks

If you're just looking to get the numbers/ppms of various inputs you could use a nutrient calculator, like hydrobuddy or cannastats, or download @renfros nutrient calculator.

The liquid silica I use is potassium silicate, not potassium phosphate and listed as soluble potash (K2O). I use it for raising ph if needed vs ph up. If you are using both silica and ph down you are adding something unnecessarily? Silica if beneficial in that it helps build stronger stalks and stems and it's pretty hard to hurt your plants with silica but if your final ph is too high, I supose I can see using ph down also. I've never had ph up or ph down have any unwanted effects on my nutrient levels other than raising overall ppm/ec.

coherent said:

The liquid silica I use is potassium silicate, not potassium phosphate

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I read that as a typo/brain fart.

Yup... Was a brain fart! I meant potassium silicate (how much does it contribute to potassium in your ratio), and phosphoric acid (contributing to phosphorous content)

sven_lordy said:

Yup... Was a brain fart! I meant potassium silicate (how much does it contribute to potassium in your ratio), and phosphoric acid (contributing to phosphorous content)

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The analysis will be listed on the product, agsil16h is 0-0-32, dynagro protekt is 0-0-3, etc.

If it were that simple I wouldn't have felt the need to ask the question! Liquid Silicon and Growth Technology pH Down don't list this information on the labels... if they did, I'd have correctly factored it already