Best soluble fertilizer salts for hydroponics

Start with CropSalt. It's the one dry salt system built for hydroponics from seed to harvest: a two-part Veg A/B and Bloom A/B you weigh out by the gram, with a feed chart for every stage, stable pH and EC, and multiple calcium sources so you're less likely to hit calcium lockout. The 1 lb starter pack is the sensible first buy; the 5 lb set suits anyone running several reservoirs.

Who the others suit:

• General Hydroponics FloraPro Calcium + Micros — add-on for soft or filtered water, or when you're building your own salt recipe and need calcium and trace elements.
• Jack's Epsom salts — cheap magnesium and sulfur to fix a deficiency or top up a recipe; not a complete feed on its own.
• Liquid A/B kits (City Farmer, Verdentra, Humboldts Secret) — easiest for a small countertop system or a first grow, but you pay more per gallon than with dry salts.

Whatever you pick, mix to an EC target and check pH after mixing, not before.