Stable parameters matter more than perfect parameters. Here are the targets every reefer and freshwater keeper should hit, plus the test kits that actually give accurate readings.
Salinity: 1.025 specific gravity (35 ppt). Use a calibrated refractometer, not a swing-arm hydrometer.
Temperature: 76-80F. Stability matters - swings of 2F+ in a day stress fish.
pH: 8.0-8.4. Driven by alkalinity + CO2 levels.
Alkalinity: 7-10 dKH. The most-tested parameter on reef tanks. Drift kills SPS first.
Calcium: 380-450 ppm. Linked to alkalinity - dose them together.
Magnesium: 1280-1400 ppm. Lock-step with calcium + alk.
Nitrate: 2-15 ppm. Below 1 = SPS pale + tang HLLE. Above 25 = algae bloom risk.
Phosphate: 0.02-0.10 ppm. Same logic as nitrate. Test with Hanna ULR.
pH: species-dependent. Tetras + rasboras: 6.0-7.0. Livebearers + cichlids: 7.5-8.5. African Rift Lake cichlids: 8.0-8.6. Match your fish to your tap water - chasing pH with chemicals destabilizes.
Ammonia + nitrite: ZERO. Always. Detectable readings = fish dying soon.
Nitrate: under 30 ppm for community, under 10 for sensitive species (discus, shrimp).
GH (general hardness): 4-12 dGH for community. Soft-water fish (cardinal tetras, discus) want 2-6.
KH (carbonate hardness): 3-8 dKH for community. Drives pH stability.
Hanna Checkers. Digital, lab-grade, 5% accuracy. Worth it for reef alk + phosphate + calcium.
Salifert. Best titration kit for reef alkalinity + magnesium. Cheaper than Hanna, slightly less precise.
API Master Kits. Solid for freshwater. Test pH, ammonia, nitrite, nitrate at the bare minimum.
Refractometer. Required for marine. Calibrate monthly with 35 ppt calibration fluid.
Live vendor inventory shipping overnight to all 50 states. Buyer Protection on every order.
Browse test kits →First 90 days: alk + ca + mg + nitrate + phosphate weekly. After stable: alk + ca every 1-2 weeks, full panel monthly. Test more often after dosing changes or new coral additions.
Stability matters more than absolute readings. Daily swings (alkalinity drop of 1 dKH overnight, temperature swing of 3F) stress coral more than slightly off targets. Trace elements (potassium, iodine, strontium) also matter long-term.
For reef: alkalinity. For freshwater: ammonia + nitrite must always be zero. For both: temperature stability and salinity (or hardness) consistency.
Recommendations on this page cross-checked against the following authoritative references and our internal vendor + breeder database.