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.
Answers to the questions experienced keepers ask after the basic care guide.
Drip acclimation over 60 to 90 minutes is the safest approach for Aquarium Water Parameters - Fast Aquatics Guide. Match temperature first (15 minute float), then drip 2 to 3 drops per second from the display sump until the bag volume has tripled. Test salinity (or freshwater hardness) at the end - if it is within 0.001 SG (or 2 dGH) of the display, transfer the specimen with a net rather than pouring shipping water in.
Aim for biological + mechanical + chemical staging. Canister or sump-driven filtration sized for 5x to 8x display turnover per hour, mechanical floss replaced weekly, and carbon or GAC swapped every 4 to 6 weeks. Aquarium Water Parameters - Fast Aquatics Guide responds well to stable nitrate (under 20 ppm) more than to any specific filter brand - stability beats peak performance.
For saltwater specimens, yes - a properly-sized skimmer rated for 1.5x to 2x display volume keeps dissolved organics low and reduces nuisance-algae triggers. Freshwater specimens do not need skimmers; a well-stocked plant grow-out + canister with chemical media achieves the same end. Aquarium Water Parameters - Fast Aquatics Guide kept without adequate organic export tends to show stress within 90 days.
Compatibility with planted tanks depends on the species behavior + water chemistry overlap. Plant-safe specimens leave foliage alone; some pick at soft-tissue plants like vallisneria or anubias. Check the species page profile + the planted-tank compatibility note before stocking Aquarium Water Parameters - Fast Aquatics Guide in a high-tech CO2-injected setup with valuable cultivars.
For freshwater specimens with no plant requirements, a basic LED at 30 to 50 PAR at substrate is sufficient and reduces algae. For saltwater + reef specimens, target 100 to 250 PAR depending on photo-tolerance, with a sunrise/sunset ramp + a 8 to 10 hour photoperiod. Aquarium Water Parameters - Fast Aquatics Guide tolerates a wider lighting band than most keepers expect; consistency matters more than peak intensity.
Most aquarium species evolved in moderate flow with localized turbulence rather than uniform high flow. Aim for 20x to 40x display turnover for reef specimens, 4x to 6x for community freshwater. Aquarium Water Parameters - Fast Aquatics Guide shows stress fins (clamped, frayed) when flow is mismatched - dial back if you see this within 14 days of introduction.
Sustained drift above +/- 2 F from target is the threshold most keepers miss. Aquarium Water Parameters - Fast Aquatics Guide tolerates day-night swings of 1 to 2 F without issue but a 4 F shift over 2 hours triggers ich + bacterial bloom risk. Use a controller-driven heater (not the built-in dial) and a backup thermometer at the opposite end of the tank.
For freshwater fish: ich, columnaris, and fin rot are the top three; quarantine + UV sterilizer prevents the majority. For marine fish: ich (Cryptocaryon), velvet (Amyloodinium), and bacterial infections; tank-transfer method or copper QT during the 30-day acclimation cycle prevents nearly all outbreaks. For inverts + corals: tissue necrosis, parasitic isopods, and protozoan blooms.
Captive breeding success varies enormously by species - some breed readily in community tanks (livebearers, cherry shrimp, clownfish) while others have never been captive-bred (most reef fish + most marine inverts). Check the species-specific care guide for the breeding-method note + larval-rearing protocol. Aquarium Water Parameters - Fast Aquatics Guide kept in pairs or small groups often spawns even without intent if conditions are right.
Avoid same-species rivals (especially male-male pairings for territorial species), known fin-nippers (tiger barbs, certain pufferfish), and anything that out-competes for food or out-grows the tank. Aquarium Water Parameters - Fast Aquatics Guide also struggles with hyper-aggressive cichlids in freshwater and damselfish in saltwater - both will hold territory at the expense of every other tankmate.
Most ornamental specimens accept cleaner shrimp + cleaner gobies; cleaner wrasses (Labroides) often die in captivity and are not recommended. Aquarium Water Parameters - Fast Aquatics Guide kept with cleaner pairs typically benefits from parasite control + stress reduction, but verify the cleaner does not get eaten by checking the species size + temperament chart.
Captive lifespan tracks closely to wild lifespan when water chemistry, diet, and tankmate stress are managed. Most aquarium fish live 5 to 12 years; long-lived species (large cichlids, pufferfish, some tangs) reach 15+ years. Aquarium Water Parameters - Fast Aquatics Guide kept in a stable, properly-sized system should live within 80% to 100% of the species lifespan ceiling - early death usually traces back to chronic-stress causes (parameters, tankmates, diet) rather than disease.