Three numbers every reefer needs and nobody writes down. No signup or email is required. The calculators work without saving; My Tank can optionally keep only your water-volume profile in this browser.
Plan Your Reef
My Tank Profile
Keep the water volumes you want to review and reuse.
Optional · saved on this deviceSave the water volumes you want to reuse in future reef-planning tools. This stores only the values below in this browser—never your name, email or contact details.
Review your tank details
Current summary
Review this tank before each calculation
A saved profile is a convenience, not confirmation that its volume is still current.
- Display
- Sump/refugium
- Net water
- Basis
- Last updated
Water Volume
Estimate display and sump water after displacement.
Estimated US gallonsThe number on the box is the glass. What matters for dosing, salt and medication is the water actually in there once rock and sand displace their share.
Rock displaces roughly 0.08 gallons per pound and dry aragonite sand roughly 0.075, which is what we use here. Both vary with porosity, so treat the result as close rather than exact.
Salt Mix
Plan a batch using the mix rate on your salt label.
Batch size · salinity · mix rateMix rate depends on the salt. Read the bucket rather than trusting a number you saw once. Most reef salts land near half a cup per gallon for 35 ppt, and that is the default here.
Mix in RODI, run a powerhead and a heater, and let it come up to tank temperature before you test. Salinity read cold will read wrong.
Electricity Cost
See what your equipment costs at your rate and runtime.
Daily · monthly · yearlyThe number people leave out of the budget. Enter what each piece of gear draws and how long it runs.
| Equipment | Watts | Hours per day |
|---|
Heaters are the one people get wrong. A 300 W heater does not draw 300 W all day, it cycles. In a heated room a third of the time is a fair guess; in a cold garage it is most of the day. The default below assumes 8 hours of actual on-time.
Working out whether a build is affordable? The full cost breakdown has real prices on every piece, and the REEFER build planner prices a complete Red Sea system from live stock. The clean up crew calculator sizes the snails and hermits for you, and the replacement parts hub has the o-rings and impellers. Need help with a Red Sea build? Use the consultation request to request a hands-on video appointment.
Log your test results
The calculators above work out what to put in. The chemistry log keeps what you measured: alkalinity, calcium, magnesium, nitrate, phosphate, pH, temperature, and anything else you test.
Readings stay in your browser on this device. Download the CSV or JSON whenever you want a copy, and import it back later.