A nano reef is roughly anything under 100 litres, and in a British flat it is often the only realistic way into the marine hobby. A 45-litre all-in-one will sit on a sideboard, run quietly and cost a fraction of what a metre-long system demands. It is also far less forgiving. When your entire water volume is the size of a bucket, a stuck heater or a forgotten top-up shows up within hours rather than days. What follows is the kit worth buying, the order to set it up in, and the weekly rhythm that keeps a small reef steady.
Pick the tank and its spot before anything else
Most people buy the tank first and then discover there is nowhere sensible to put it. Work backwards instead. A 60-litre tank filled with water, rock and sand weighs comfortably over 80kg, and that weight sits on four small corners. Check the surface can take it, and that a spill will not run straight under a laminate floor.
Then think about light and temperature. A tank in front of a south-facing window will grow algae faster than you can scrape it, and a radiator underneath will cook the water in July. You want a spot out of direct sunlight, away from draughts, and within reach of a socket you can protect with an RCD. All-in-one tanks with rear filter chambers are compact and quiet; a small sump adds water volume and hides equipment but needs cabinet space you may not have.
The essential equipment checklist
Everything below is genuinely needed. Anything else can wait until the tank has been running a few months.
- Tank and stand — 40 to 60 litres is a good compromise between stability and footprint.
- Live rock or dry rock — the main biological filter. Roughly 10 per cent of tank volume is a common starting point.
- Return pump — usually supplied with an all-in-one; check it turns the tank over several times an hour.
- Wavemaker — small and adjustable. Corals want movement, not a washing machine.
- Heater with a separate controller — the controller is the insurance. Heaters fail both ways, and 25 litres of cooked water is a dead reef.
- Lighting — an LED unit sized to the tank. Soft corals and LPS are realistic; demanding SPS need more light and more discipline.
- Refractometer — not a swing-arm hydrometer. Salinity is the number you will check most often.
- Test kits — ammonia, nitrite and nitrate for the cycle; alkalinity, calcium, magnesium, nitrate and phosphate afterwards.
- Reverse osmosis water and marine salt — either a small RO unit or a reliable local supply. Tap water brings phosphate and nitrate with it, particularly in hard-water areas.
- Thermometer, glass magnet and a siphon — cheap, used constantly.
- Buckets, jug and towels that never touch household cleaners.
Two additions that make small tanks easier
An auto top-up unit is the single best upgrade for a nano. Small tanks lose a surprising amount to evaporation, and that loss concentrates the salt. A float switch and a small pump connected to a reservoir of RO water keeps salinity stable through the week, especially in winter when heating dries the air.
The second is a battery-powered air pump. Power cuts are brief but they starve a small volume of oxygen quickly. An airstone running off batteries will hold things together for a few hours, and it costs very little to keep in a drawer.
Water, rock and the first few weeks
Mix salt to around 35 parts per thousand, or a specific gravity of roughly 1.025, at 24 to 26°C. Let it circulate for a few hours before use and check it with the refractometer. Fill the tank, add rock and a shallow sand bed if you want one, and then leave it alone. The tank will cycle: ammonia rises, then nitrite, then nitrate. Testing every couple of days tells you where you are, and once ammonia and nitrite read zero consistently, you can start adding livestock slowly.
Slowly means one small fish, then nothing else for two or three weeks. A couple of snails and a shrimp can go in earlier. Resist the urge to fill the tank in a weekend; a nano that is fully stocked in its first month usually ends up as a nano that crashes in its third.
The weekly routine
Daily, two minutes
- Check the temperature on the controller, not just the heater.
- Look at every fish and coral. Behaviour and colour tell you more than test results.
- Check the water level in the top-up reservoir.
Weekly, about an hour
- Clean the glass with the magnet, including the corners.
- Change 10 to 20 per cent of the water with pre-mixed salt water at the right temperature.
- Siphon any debris from the sand and around the rock.
- Rinse sponges and filter floss in the old tank water, never under the tap.
- Empty and clean the skimmer cup if you run one.
- Test alkalinity, nitrate and phosphate, and salinity after the change.
- Check pump and wavemaker intakes for trapped snails or algae.
- Feed a varied diet, and only what the tank clears in a couple of minutes.
Monthly
- Soak pumps and the wavemaker in a citric acid solution to strip calcium deposits.
- Replace carbon or other chemical media.
- Inspect every cable and plug for salt creep, and wipe it away.
- Test calcium and magnesium, and calibration-check the refractometer.
Mistakes that hurt more in a nano
Overstocking is the classic one. A small tank has a small margin for waste, and three extra fish can push nitrate somewhere no water change will fix. Overfeeding runs a close second; uneaten food decays where you cannot see it.
Chasing numbers is another. Dosing alkalinity or calcium without testing first, or making large water changes to correct a reading, swings parameters faster than the animals can cope with. Smaller, more frequent changes are almost always safer. Finally, do not skip quarantine or a careful acclimation for new arrivals. In a system this size, one introduced problem affects everything.
Where to start this weekend
Decide your spot, order the tank, heater controller, refractometer and test kits, and sort out your RO water supply before the tank arrives. Set it up with rock and water, let it cycle without livestock, and use those quiet weeks to plan your stocking list properly. Once it is running, the routine above takes an hour a week. Keep a notebook or a phone note of your test results and water changes; patterns show up surprisingly quickly when you can see them written down. Small reefs reward patience more than equipment, and a modest tank that is stable for a year looks far better than an expensive one that never settles.
Photo: churananngm / Pixabay
