GOAT LabAquaLab: 16 aquarium, reef & water chemistry calculators
AquaLab is a free, fully client-side set of 16 aquarium and reef calculators — tank volume and stand load, heater wattage, glass thickness, CO2 from pH/KH, salinity conversion, stocking level, fertilizer dosing, and reef two-part (alkalinity, calcium, magnesium) — that run instantly in your browser, with two static reference tables for water parameters and standard tank sizes.
- Free
- No sign-up
- Works offline
What is AquaLab?
AquaLab bundles 16 tools for setting up and maintaining freshwater and marine tanks (14 calculators plus 2 reference tables): tank volume and filled weight, glass thickness and safety factor, heater wattage, stocking level, flow rate and turnover, substrate amount, CO2 from pH/KH, a salinity converter, water change and nitrate dilution, fishless-cycling ammonia dosing, evaporation and ATO reservoir sizing, planted-tank fertilizer dosing (EI/PPS-Pro), salt mix, reef two-part (alkalinity/calcium/magnesium) dosing, plus water-parameter and standard-tank-size reference tables. Everything computes locally with no server, account, or upload.
How does it work?
Each calculator applies a single published formula or hobby convention: heater wattage comes from a watts-per-gallon curve scaled by the temperature difference (ΔT), glass thickness uses Roark's flat-plate stress formulas rounded up to stock sizes, dissolved CO2 comes from the classic pH/KH carbonate-equilibrium relation, and reef alkalinity, calcium and magnesium doses come from stoichiometric salt masses with daily safety caps. Inputs are validated against realistic ranges, and every result names the source convention it follows.
When should I use it?
Use AquaLab when setting up a new tank (sizing a heater, checking stand load, estimating glass thickness), dosing ammonia during a fishless cycle, dialing in CO2 or reef alkalinity/calcium/magnesium, or planning a water change. The glass-thickness tool is a DIY planning aid — treat its output as a reference and confirm the final thickness with your glass supplier, and have large or rimless builds checked by a professional. The stocking estimator is a rough guideline, not a hard limit; research each species before stocking, especially goldfish, cichlids, and marine fish.
At a glance
| Calculators & tables | 16 total — 14 calculators + 2 reference tables, across 4 categories |
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| Heater sizing | 2.5–5 W per US gallon by ΔT; rounds up to standard sizes 25–500 W |
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| CO2 from pH/KH | CO2 (ppm) = 3 × KH(dKH) × 10^(7.00−pH); KH 4 + pH 6.6 → 30 ppm |
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| Glass thickness | Roark's flat-plate method; rounds up to stock sizes 4–19 mm |
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| Reef salinity reference | Natural seawater 35 ppt = SG 1.0264 = 53.1 mS/cm at 25 °C |
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| Two-part dosing caps | Alkalinity ≤1.4 dKH/day, Ca ≤50 ppm/day, Mg ≤100 ppm/day |
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| Fertilizer presets | EI (Estimative Index) and PPS-Pro, dry-salt or solution dosing |
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| Processing | 100% client-side — no server, no account, no upload |
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Frequently asked questions
How many calculators does AquaLab include?
AquaLab includes 16 tools across 4 categories: 6 tank & hardware calculators (volume, glass thickness, heater size, stocking, flow rate, substrate), 5 water-chemistry calculators (CO2, salinity, water change, ammonia dosing, evaporation/ATO), 3 dosing calculators (fertilizer, salt mix, reef two-part), and 2 reference tables (water parameters, standard tank sizes).
What size heater does a 60 cm aquarium need?
For a 60 cm tank holding about 55 L of water, heated 5 °C above room temperature (25 °C target, 20 °C room), AquaLab's hobby-standard 2.5 W-per-US-gallon rule gives roughly 36 W, rounded up to a 50 W heater. Colder rooms or a bigger ΔT push this toward 75–100 W, or split it across two heaters above 300 W for even heating and redundancy.
How do I calculate CO2 concentration from pH and KH?
Dissolved CO2 (ppm) = 3 × KH (dKH) × 10^(7.00 − pH). At a common planted-tank KH of 4 dKH and pH 6.6, that works out to about 30 ppm — the typical CO2-injection target. The formula assumes carbonate-only alkalinity, so it reads high with active substrates, peat, or phosphate buffers; always cross-check with a 4 dKH drop checker.
How thick should aquarium glass be?
AquaLab applies the Roark's-formulas flat-plate method used by DIY tank builders: for example, a 900×450×450 mm tank at a 3.8 safety factor needs about 8 mm glass on the sides and 12 mm on the bottom, rounded up to stock thicknesses. Treat the result as a planning reference only — always confirm final thickness with your glass supplier, and have large or rimless builds checked by a professional.
How accurate is the stocking level estimator?
It shows two classic guidelines side by side — inch-per-gallon and Dick Mills' surface-area rule — as a rough starting percentage, not a precise limit. Both assume slender community fish; they don't apply to goldfish, large or deep-bodied fish, territorial cichlids, or any marine species, and neither accounts for aggression or filtration capacity, so research each species' adult size and needs before stocking.
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