Hydroponic Nutrients for Coco, Rockwool & Inert Media

Hydroponic nutrients are complete mineral feeds designed for inert media and water culture, where the plant gets nothing except what you put in the tank. They are more precise than soil feeds, less forgiving, and the reason hydroponic growth rates are what they are.

Why they come in two parts

Almost every hydroponic feed is sold as A and B. This is not marketing – calcium in part A and phosphates and sulphates in part B will react and precipitate out if they sit together in concentrated form. You would lose both, visibly, as sludge in the bottom of the bottle. Always add A to the water, stir, then add B. Never mix the concentrates.

Hard water or soft water?

Most hydroponic lines come in both. Croydon and most of the south-east is hard water, so the hard water formulation is usually right – it accounts for the calcium and magnesium already in the supply. If you run RO or heavily filtered water, use the soft water version and expect to add CalMag. Getting this wrong is the most common cause of unexplained deficiencies in hydro.

What matters in a hydro system

• EC, not the feed chart. Charts are a starting point. The reservoir tells you the truth – see pH and EC management.
• pH 5.5-6.2. Lower than soil. Different nutrients lock out at either end of that range.
• Reservoir temperature. Above about 22°C, dissolved oxygen falls and pythium takes hold. This causes more hydro failures than nutrition ever does – see water chillers.
• Change the tank. Nutrients are taken up unevenly, so a recirculating reservoir drifts out of balance. Change it weekly rather than topping up indefinitely.

What we stock

A+B lines from Canna Aqua and Hydro, Athena, Terra Aquatica, Shogun, Dutch Pro and House & Garden. Add flowering boosters and root stimulators as needed, or start with a matched nutrient starter kit. Growing in coco or soil instead? See base nutrients.

Why buy hydroponic nutrients from The Hydro Bros?

We are a hydroponics shop in Croydon, we run these systems, and we know the local water hardness. Tell us your system and your source water and we will pick the right formulation. Discreet UK and European delivery, and excellent customer reviews on Trustpilot.