Tools
Reef tools & calculators.
The interactive data other reef sites don’t have. Built to answer the size- and setup-specific questions forums answer badly — and Google can’t summarize away.
Return Pump Calculator
Enter your tank size, head height, and plumbing → the real flow each of 41 pumps delivers at your total dynamic head, ranked, with the math shown.
Live · FreeProtein Skimmer Size Calculator
Enter your tank volume + bioload → which skimmers actually fit once we derate the optimistic manufacturer ratings, ranked, with footprint and price.
Live · FreeReef Tank Cost Calculator
Itemized up-front cost + monthly running cost (electricity, salt, consumables) for any tank size and build tier.
Live · FreeSalt Cost-per-Gallon Calculator
Compare 12 reef salts by real cost per mixed gallon — not the box price — plus your actual monthly salt cost.
Live · FreeReef Dosing Calculator
Alk, calcium, or magnesium — the exact dose to hit your target, split safely across days, for DIY and bottled two-parts.
Controller Comparison
Apex vs GHL vs Hydros vs budget — feature-by-feature, filterable.