I believe commercial Cal-Mag uses Calcium Nitrate and Magnesium Nitrate.
I am a home brewer and am used to adding acids to lower pH and salts to create brewing liquor in ppm per gal. I have calcium chloride, calcium sulfate (gypsum), calcium hydroxide (pickling lime), and calcium bicarbonate (calcium hydrogen carbonate), as well as Epsom salt (magnesium sulfate). Does anyone have a recipe for Cal-Mag using these salts?
Without a recipe I have simply been carbon filtering my tap water to eliminate chlorine then lowering pH using 10% phosphoric acid. The filter does not remove the 39 ppm Calcium and 6 ppm Magnesium in my municipal water supply.
I am just wondering if this is too much of one and not enough of the other. I am thinking a 6:1 ratio should be more like 3:1 in which case I can add 7 ppm magnesium by adding ~1 gram Epsom salt in 3 gal of my filtered water to bring the mag up. It will also add 33 ppm sulfate.
I don’t have answer to your question, but I would check hydro buddy or try Google searching for a recipe. There is probably at least a few out there. I use calcium nitrate in my base, usually just tweak on that if needed.
There’s definitely a ratio out there. Jacks 3-2-1 uses 2.4g/G of their part B which is primarily calcium nitrate and 1.2g/G of Epsom salt. Part A also has what those give so I wouldn’t go purely off that. Which uses 3.6g/G. If that helps any. Lot of math there. But it does tell one they are usable. Since a lot of us are doing almost exactly that.
Update: Watched a video where Mr Grow It interviewed a guess who uses gypsum. Epsom Salt has been used for years. I have both so I added a tsp each to a quart jar of Recharge, pH-ed to 6.5 and added one each to my plants. They loved it.