DWC Nutrient Dosing Calculator
Build a week-by-week feeding plan for a deep water culture reservoir. Set a starting dose, a weekly step and how often you change the water.
How the schedule is built
For each week the dose per litre is the starting dose plus the weekly step, never above your maximum. The amount to add is that dose times the reservoir volume:
Dose in week n = min(start + (n − 1) × step, maximum) and ml to add = dose × litres
Example: with a 20 litre reservoir, a start of 1 ml/L and a step of 0.25 ml/L, week 1 needs 1 × 20 = 20 ml, week 2 would be 1.25 ml/L, and week 3 needs 1.5 × 20 = 30 ml. Doses are added when you fill the reservoir with fresh water, so with a change every 2 weeks the schedule lists the amount to add in weeks 1, 3, 5 and so on. In the weeks in between, top off with plain water and check EC and pH instead of adding the full dose again.
Want the dose for a single week or for several parts at once? Use the hydroponic nutrient calculator. To size the tank first, see the reservoir volume calculator.
Use the numbers from your nutrient's feeding chart. This is a planning aid, not a replacement for checking EC and pH.
Frequently asked questions
How often should I change the water in a DWC system?
Many growers change the whole reservoir every one to three weeks, sooner if the water smells, turns cloudy or the readings drift. The schedule here lets you pick the interval that suits your setup.
Why does the dose go up each week?
Young plants need a lighter solution and bigger plants take up more. Most feeding charts start low and step up. Enter the first-week dose and the weekly increase from your nutrient's chart, and optionally cap it at the maximum the label allows.
What do I do between water changes?
Top off with plain water as the level drops, and check EC and pH every day or two. If EC climbs, the plants are drinking water faster than nutrients, so add water rather than more nutrient.
Do I enter every nutrient part?
Run the calculator once for each part, using that part's dose. Or enter the combined dose per litre of all parts if you want a single total for the concentrate.