A working reference written by our marine technicians — the parameters, routines and equipment decisions that keep a UK saltwater tank healthy long term. If you'd rather outsource it entirely, our nationwide team services FOWLR and full reef systems.
For most reef and FOWLR systems, a 10–20% water change every 1–2 weeks keeps nutrients stable and replenishes trace elements. Lightly stocked tanks with a mature refugium can stretch to monthly; heavily stocked SPS reefs often prefer smaller, more frequent changes.
Fish-only systems sit comfortably at 1.020–1.025 specific gravity. Reef tanks should be held at 1.025–1.026 (35 ppt) and — more importantly — kept stable. Use a calibrated refractometer, not a swing-arm hydrometer.
Target pH 8.1–8.4, alkalinity 8–9 dKH, calcium 410–450 ppm, magnesium 1280–1350 ppm, nitrate 1–10 ppm, phosphate 0.03–0.10 ppm and temperature 25–26°C. Stability matters more than chasing perfect numbers.
Always use RO/DI water with 0 TDS. Tap water introduces phosphates, silicates, copper and chloramine that fuel algae and harm invertebrates.
Combine larger water changes with refugium macroalgae, a properly sized protein skimmer, GFO for phosphate, biopellets or carbon dosing for nitrate, and reduced or higher-quality feeding.
Use a dedicated magnetic glass cleaner, a turkey baster to blast detritus from rockwork, and a clean siphon during water changes. Never use household soaps or chemicals — even trace residues are lethal to invertebrates.
Diatoms are normal in new tanks (first 4–8 weeks) as silicates are consumed. If they persist, check your RO/DI membrane and resin, reduce lighting hours, and add a clean-up crew including Nassarius snails and Cerith snails.
Filter socks every 3–5 days to prevent nitrate spikes. Carbon and GFO every 3–4 weeks. Skimmer cup cleaned weekly, skimmer body and pump every 1–3 months.
Weekly: top-off check, glass clean, skimmer cup empty, parameter test, 10% water change. Monthly: filter media swap, pump impeller clean, salt creep wipe-down, light schedule review and a full ICP test every 1–2 months.
Yes. A 4–6 week quarantine in a separate tank prevents marine ich (Cryptocaryon), velvet and flukes from wiping out your display. Treat prophylactically with copper or tank-transfer method as appropriate.
Ich shows as discrete white salt-grain spots and flashing. Velvet is a fine gold-dust sheen, rapid breathing and sudden death — far more aggressive. Both demand immediate isolation and treatment in a quarantine tank.
Common causes: unstable alkalinity, low nutrients (nitrate/phosphate at zero), too much or too little light, sudden parameter swings, or pest predation. Investigate one variable at a time.
Test daily for a week to measure consumption, then dose the same daily amount split between calcium and alkalinity (never simultaneously in the same spot). For larger demand, switch to a calcium reactor or two-part auto-doser.
Add salt mix to RO/DI water (never the reverse), circulate with a powerhead and heater for 24 hours, then verify salinity with a refractometer before use.
Aim for 20–40x display volume per hour in turnover. Soft corals and LPS prefer gentler, varied flow; SPS dominated tanks often run 40–60x with gyre or wavemaker pumps.
For anything beyond a small nano, yes. A skimmer removes dissolved organics before they break down into nitrate and phosphate — the single biggest contributor to water clarity and coral health.
Keep a battery air pump or DC return pump with battery backup, insulate the tank with blankets to retain heat, and avoid feeding until flow returns. A small inverter or UPS on the return and a heater is worth the investment.
Our marine-trained technicians handle water testing, RO/DI top-ups, skimmer servicing, glass and rockwork cleaning, coral health checks and parameter dosing — anywhere in the UK.