Chemist endorses the use of reagent grade salts for his formulations. If practical or agro grade salts are used, it should work just as well. Some things, like MES buffer, might be tough to find outside of lab catalogs.
MICRO FORMULAE
OK first micronutes. I keep two stock solutions - one acidic, and one alkaline. These stock solutions provide Cu, Zn, Fe, Mn, B, Si, Mo, Cr and Co. I also added some EDTA to chelate Fe, Zn and Cu.
Acidic micro mix
To make 1 liter of 1000x:
Iron (III) nitrate nonahydrate 30.7 g
Copper (II) nitrate x2.5 H2O 920 mg
Manganese (II) sulfate monohydrate 6.0 g
Zinc sulfate heptahydrate 2.20 g
Chromium (III) nitrate 10 mg
Cobalt(II) nitrate hexahydrate 10 mg
Nitric acid 70% 3.2 ml (to yield 1/20 N nitric)
Dissolve in water and dilute to a final volume of 1 liter.
Alkaline micro mix
To make 1 liter of 1000x:
Sodium silicate, 42 degrees syrup 50 g
Sodium tetraborate decahydrate 17.7 g
Sodium molybdate dihydrate 2.5 mg
EDTA free acid, 10 g
Sodium hydroxide 16 g
VEG FORMULAE
Veg mix
I use a two-component veg mix. Component 1 handles Ca, N and P (and some K). Component 2 handles K, S and Mg.
This mix gives fairly gentle final nutrient concentrations. It was designed to be easy on the plants and to be supplemented or changed frequently.
For 250 liters finished nute or 1 liter of 250x stock:
component A (Ca N P)
Calcium nitrate tetrahydrate 220 g
Potassium dihydrogen phosphate 55 g
water to 1 liter.
component B (K Mg S)
Potassium sulfate 85 g
Epsom salt 190 g (or 93 g anhydrous MgSO4)
MES (morpholinoethanesulfonic acid, a buffer) 25 g
The phosphate and the calcium nitrate are COMPLETELY predissolved in water before compounding. When I had traces of undissolved phosphate, calcium phosphate began to precipitate. This process is irreversible.
To make up a 40 liter reservoir, I add 40 ml of each of the micros to 40 liters of RO water, then 160 ml from each of my macronute stocks. Final TDS is around 1200. pH is in the fives, and I keep the pH between 5.0 and 6.0 during the grow. The MES helps tremendously in accomplishing this.
ppm levels for the veg mix: N 100 P 50 K 212 Ca 143 Mg 75 S 118
To boost Ca and S, I sometimes add 21.4 grams gypsum
FLOWER MIX - COLA DIET
To make 50 liters of Cola Diet(this provides N 75 P 100 K 150 Ca 200 Mg 75 S 185):
Calcium sulfate dihydrate (gypsum) 20.4 g
Epsom salt 37 g
Potassium sulfate 2.61 g
Potassium dihydrogen phosphate 21.93 g
Calcium nitrate tetrahydrate 30.5 g
MES 4 g
I weighed out the dry salts and dissolved them directly in the reservoir. The gypsum was the last item in, and it did dissolve. Using RO water the TDS on my Oakton pen read around 800. Nice and gentle on the ladies’ feet.
A 50 liter reservoir would be eaten up within 5 days by 20 square feet of canopy.