Understanding Nutrients in Hydroponics
Hydroponic nutrients are more concentrated and immediately available than soil nutrients. Understanding how to mix and manage them correctly is the key skill in hydro growing.
The Three Part Nutrient System
Most hydroponic nutrient lines come in three parts: Grow (high nitrogen for vegetative growth), Bloom (high phosphorus and potassium for flowering), and Micro (trace elements and calcium/magnesium). Mix them in the order: Micro first, then Grow or Bloom, then any additives. Never mix concentrates together directly — always add each to water separately.
Measuring EC
EC (Electrical Conductivity) measures how much dissolved salt (nutrients) is in your water. It is measured in mS/cm or µS/cm. A digital EC meter is your tool for knowing how concentrated your nutrient solution is. Too low EC means plants are hungry, too high causes nutrient burn — brown, crispy leaf tips.
Cal-Mag in Hydroponics
Calcium and magnesium deficiencies are extremely common in hydroponics, especially with RO (reverse osmosis) or very soft water. Symptoms: brown spots on leaves (calcium), yellowing between leaf veins (magnesium). Most experienced hydro growers add a calcium-magnesium supplement as a baseline to every reservoir fill.
Flushing Before Harvest
Two weeks before harvest, switch to plain pH-adjusted water with no nutrients. This flushes accumulated salts from your medium and the plant itself, improving final taste and smoothness. In DWC, simply refill reservoir with pH-adjusted water only. EC should drop to near 0 by harvest day.
Quick Tips
- Buy a good EC meter — cheap ones drift badly. Bluelab and Apera make reliable options.
- Keep detailed notes of your nutrient schedule per strain — different strains have different requirements.
- Never exceed 3.0 EC for cannabis — even heavy feeders rarely benefit beyond this.