I already put together a different DIY for CalMag+, however if you want to be even more hands-on, you can make some 100% organic CalMag+ at home using only egg shells and molasses and apple cider vinegar, for just pennies a gallon. Considering that it currently sells for around $20 a quart, that is quite a savings.
Gather together the equivalent of a dozen egg shells.
Wash the egg shells and allow them to dry. Make sure that the only part remaining is the shell - remove the inner lining of the shell, etc., then put in a dry spot and allow to dry thoroughly (several days is best).
After the egg shells are dried, break them in to small confetti-sized bits, and heat them in a dry frying pan until they are brown and black, with a mixture of some white shells also.
Grind the egg shells up in to a fine powder using a coffee grinder or a blender.
Measure your egg shell powder to see how much volume you have, and place the powdered egg shells in to a very large glass jar and place the jar in to your sink, and add 5 parts organic apple cider vinegar to 1 part powder. So, if you have 100 ml of powdered egg shell then add 500 ml of vinegar. - Do not cap the jar. Make sure there is plenty of space for the reaction to take place in the jar, it will need a lot of room, which is why its a good idea to put it in the sink in case it bubbles over a bit.
Allow the vinegar and egg shell powder to react together for about 12 hours, at which point you shouldn’t see any more activity in the jar. If you do, then allow it to finish the reaction and settle down completely.
Place the liquid in to a jar and seal it, and and allow it to sit for 3 weeks.
After 3 weeks filter the remaining substance in to another jar, and keep the liquid and strain out the remaining eggshells etc…You have made water-soluble calcium acetate.
Add 1 teaspoon of calcium phosphate per gallon of water.
Add 1 tablespoon of unsulphured organic blackstrap molasses to each gallon of water and calcium phosphate mix, and you have homemade CalMag+
DIRECTIONS FOR USE:
For best results, use with every watering with standard fertilizer program.
Soil Gardens: Use 1 tsp per gallon of water.
Accelerated Formula: Use 2 tsp per gallon of water.
Hydroponics: Use with preferred hydroponic formula. Desired range of nutrients are:
Nitrogen (N) …… 160-250 ppm
Magnesium (Mg) …… 45-75 ppm
Calcium (Ca) …… 160-280 ppm
Iron (Fe) …… 2-7 ppm