Reef calculator

Water Change Planner Calculator

See how much of a buildup your water change routine really clears out over time.

gal

How this works

Each change keeps (1 − share changed) of whatever is in the water, so after n changes (1 − p)ⁿ is left. Many small changes and a few big ones of the same total volume end up close; the steady routine is what counts.

Water Change Planner

Questions

Is 10 percent a week enough?

For most reefs, yes. It clears about two thirds of a buildup in three months and keeps trace elements topped up.

Do I need water changes if I dose?

Dosing replaces what corals use. Water changes remove what builds up. Most tanks need both.

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