Aquarium calculators without the folklore.

Standard 10 gallon

20 × 10 × 12 in · 10 US gal

20 gallon long

30 × 12 × 12 in · 19 US gal

Standard 29 gallon

30 × 12 × 18 in · 28 US gal

40 gallon breeder

36 × 18 × 16 in · 45 US gal

Standard 55 gallon

48 × 13 × 21 in · 57 US gal

Standard 75 gallon

48 × 18 × 21 in · 79 US gal

90 gallon

48 × 18 × 24 in · 90 US gal

120 gallon

48 × 24 × 24 in · 120 US gal

125 gallon

72 × 18 × 21 in · 118 US gal

180 gallon

72 × 24 × 25 in · 187 US gal

Innovative Marine NUVO 30L

24 × 18 × 16 in · 30 US gal

Red Sea Reefer 250

36 × 22 × 21 in · 72 US gal

Aquarium volume

Rectangular, cube, cylinder, hex, bow-front. Inches or cm in; gallons and litres out.

Aquarium weight

Total filled weight plus PSI on the floor. Plan the upstairs build.

Substrate

Pounds of sand or crushed coral by published CaribSea bulk densities.

Aquarium gravel

Pounds of gravel for any freshwater fish tank — 1–2 in bed, exact bag count.

Aquarium sand

Aragonite or silica sand by footprint and depth. SSB / DSB / bare-bottom guidance.

Glass thickness

Minimum annealed or tempered thickness with SF=3.8. For DIY builds and sanity-checking imports.

Stocking

Freshwater inch-per-gallon with surface adjustment; qualitative saltwater bioload index.

BRS calculator alt

Open alternative to BRS’s reef calculator. Same Randy + BRS Pharma recipes, plus AFR, Red Sea, Triton.

All-For-Reef (AFR)

Tropic Marin AFR daily dose by tank volume and dKH consumption — 1 mL per 25 L per dKH.

Red Sea Foundation

Red Sea Foundation A/B/C daily doses with the manufacturer’s per-mL ppm constants.

Alkalinity dosing

Randy Recipes, BRS Soda Ash, Tropic Marin AFR, Red Sea Foundation B, Triton Base 1.

Calcium dosing

Randy CaCl₂, BRS Pharma, Red Sea Foundation A, Triton dry.

Magnesium dosing

Randy Recipe 3A, BRS Pharma, Red Sea Foundation C, Triton dry, Tropic Marin Bio-Mg.

Kalkwasser

Saturation mix and daily-dose by evaporation rate.

Reef health

Eight-parameter snapshot with colour-coded bands and one-click fixes.

Water change

Predict the post-change parameter for any dilution.

Salt mix

Dry salt mass per brand — Instant Ocean, Reef Crystals, Red Sea, Tropic Marin, Fritz RPM.

Salinity

SG ↔ ppt ↔ mS/cm with hydrometer temperature correction.

CO₂ / pH / alk

Henderson-Hasselbalch carbonate solver. Two of three; we give you the third.

Return pump flow

GPH for reef sumps by display volume, turnover target, and head loss. Inflated for elbows.

Heater wattage

BRS rule-of-thumb with insulation tier and redundant-pair recommendation.

Chiller sizing

BTU/hr heat load by equipment wattage and ambient drop. JBJ / TECO nameplate sizes.

Kalk drip rate

mL/min drip matched to evaporation. Ca and alk added per day with pH-spike guard.

CO₂ scrubber

Sofnolime media life for skimmer-mounted CO₂ scrubbing when indoor air drops your pH.

PAR / PPFD underwater

MQ-510 vs MQ-500 immersion factor with coral-specific PAR bands.

Sump baffles

Chamber widths, bubble-trap span, baffle heights, and section gallons for a DIY sump.

Stocking (FW + SW)

Three methods side-by-side — bio-load, surface area, inch-per-gallon — with temp/pH/schooling compatibility checks.

Evaporation

Daily and weekly evaporation by surface area, temp delta, humidity, cover, and air movement. Sizes the ATO reservoir.

DLI

Daily Light Integral from PAR × photoperiod, with coral and planted target bands.

GFO / phosphate dose

Cross-brand GFO, BRS HC, Seachem PhosGuard, and lanthanum chloride. Replacement schedules + overdose guard.

Electric bill

Per-device wattage × duty × your rate. Itemised monthly + annual cost.

Biopellet dose

NP-reducing pellets (Vertex, NPX, TLF). Volume by tank size, 4-week ramp, reactor flow.

Phyto dose

PhytoFeast / Nanno / Brightwell. Per-dose mL, weekly total, bottle-life.

Direct salt addition

Raise salinity without a water change. Grams + ounces + cups, with daily-swing safety cap.

Two-part imbalance

Check whether alk + Ca dosing is in stoichiometric balance. Find the leak in your dosing.