Three numbers every reefer needs and nobody writes down. No signup, no email, nothing saved. We built these because we get asked all three on the phone every week.
What your tank actually holds
The 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 0.36 gallons per pound and dry aragonite sand roughly 0.29, which is what we use here. Both vary with porosity, so treat the result as close rather than exact.
Salt for a water change
Mix 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.
What it costs to run, per month
The 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. Stuck on something specific, call the shop on 305-850-9949 and ask for Jamie.