Free tool
Reef cleanup-crew calculator
Snails, hermits, a bubble-algae crab — how many does your tank actually need? Enter your volume and what you're dealing with, and we'll size a conservative crew. Forget "one snail per gallon" — overstock a cleanup crew and it starves.
How to actually use a cleanup crew.
- Start with this crew, then watch for two weeks. Still losing to algae? Add a few more — it's far easier than fixing a mass die-off from overstocking.
- A crew supplements good husbandry (nutrient export, feeding less, water changes) — it never replaces it. If algae keeps winning, the fix is usually nutrients, not more snails.
- Drip-acclimate every invert slowly, and never put copper in a tank with them.
Sources & method
- Grazing snails ~1 per 2–3 gal · nassarius ~1 per 3–4 gal · hermits ~1 per 5–10 gal · halve for new tanks — modern consensus (Top Shelf Aquatics, AllCorals).
- Species rates & behaviour from our own fact-checked care guides: trochus, nassarius, emerald crab, peppermint shrimp.
- The outdated "one snail per gallon" rule overstocks and starves the crew — skip it.
A free Coralkin tool — no sign-up, nothing saved. It sizes a sensible starting crew; your tank and your own eyes decide the rest. We never guess a care number.