The best mix I've found is using a 2:2:1 ratio of Masterblend 4-18-38, Calcium Nitrate 15.5-0-0, and Epsom salt.

I use this online calculator for the right mixes and mix the dry powders on a kitchen scale, then into the water.

Then I'll add in some Hydroguard using the chart on the bottle,

and a few crushed up bits of a Mosquito dunk into the main reservoir.

This should cover almost all your macro and micronutrient needs for just about any plant I can think of, as well as provide bacterial protection against both waterborne insects, and bad bacteria that cause root rot; especially in warmer climates or outdoor systems.

I hope this helps!