Dolphin Nautilus CC Plus — pool cleaning on autopilot

The verdict

Start with the arithmetic, because for a pool robot the arithmetic is the review. A manual pool clean in the UK runs £40 a visit, and a covered pool that gets real use wants one a week through the season. Over our 22-week summer that's £880. A new Nautilus CC Plus is £599; a used one is £250–£350. Ours completed 61 of 63 scheduled cleans, climbed the walls on 57 of them, and cost roughly £9 in electricity for the whole season. The robot pays for itself before August — a used one pays for itself before the water's warm enough to swim in.

It is not a sophisticated machine. There's no app worth having, no mapping, and its coverage pattern looks like a toddler's crayon work — it just happens to arrive at a clean pool anyway. The two honest costs are the filter-rinse discipline covered below, and the tracks, which are the wear item that decides whether a used unit is a bargain or a project. Hence the dry test: run it out of the water for ten seconds and listen. A healthy unit whirs; a tired one grinds.

How we tested

One full UK season — May to October — on a 9 × 4 m covered outdoor pool with a tiled floor and fibreglass walls, plus fortnightly guest sessions in a neighbour's indoor pool to check behaviour on different surfaces. Debris scores use our weighed-recovery method: a measured 50 g mix of sand, leaf fragments and grass clippings distributed per zone, filter contents dried and weighed after each cycle. Wall climbs and waterline passes were counted on video, because standing at the edge of a pool with a clipboard for two hours is exactly the job we bought the robot to avoid.

The filter routine nobody warns you about

Here is the ownership texture the brochure omits: every single clean ends with you lifting a 9.5 kg robot out of the water, popping the top-load basket, and hosing out two filter panels. It takes four minutes. It is not optional. Skip it once and the next cycle's pickup drops from 93% to 89%; skip it twice and the robot starts doing a slow, wheezy impression of a clean while redistributing fine silt across your pool floor. We tested a three-clean skip in June, purely for science, and spent twenty minutes scrubbing dried algae paste out of the panel pleats as penance.

The rinse itself is easy — the panels clip out without tools and a garden hose does the job. The discipline is the hard part, and it's why so many of these appear on the used market with 'hardly used' in the listing. They were used exactly until the owner discovered the four-minute tax, and then they weren't. That's good news for buyers: a lapsed owner's robot often has very few real hours on it. Check the filter panels for permanent staining to tell the lapsed owners from the liars.

What wears out

Three things, in order of expense. The tracks: rubber, replaceable, £35 the pair, and good for roughly three seasons of weekly use before they glaze and start slipping on wall climbs — a robot that used to climb and now doesn't usually needs tracks, not sympathy. The track bearings behind them are the pricier failure at £60–£80 fitted, and they announce themselves with the grind you're listening for in the dry test. The active scrubbing brush is £25 and ours showed measurable bristle wear at season's end; call it a two-season part. The impeller rarely fails but loves to eat hair bands and pine needles — a £0 fix if you clear it, a seized £45 motor-service if you don't notice for a month. Budget £40–£60 a season in parts averaged out, which still leaves the £40-a-visit maths embarrassingly one-sided.

Who shouldn't buy one

• Above-ground vinyl pool owners — the climbing tracks are too aggressive for soft liners, and Maytronics says so in the small print.
• Very small pools — under about 6 m, a manual vac takes fifteen minutes and doesn't need its filters rinsed. The robot's economics need a pool big enough to be a chore.
• Anyone unwilling to do the four-minute filter rinse after every clean — this robot punishes neglect faster than any vacuum we've tested.
• Uncovered UK outdoor pools with heavy leaf fall — the fine-filter panels clog mid-cycle under autumn load; you want a leaf-bag cleaner first and this second.

Buying a used Nautilus CC Plus — the 5-minute checklist

• Run the dry test: power it on out of the water for ten seconds. Smooth whir is fine; any grinding from the tracks means bearing wear — £60–£80 to put right, so price accordingly or walk.
• Spin each track by hand and check the rubber for glazing, cracks or missing lugs — tired tracks are why used units 'won't climb any more'.
• Inspect the full length of the blue cable for kinks, nicks and corkscrew memory — a permanently twisted cable tangles every clean and isn't cheap to replace.
• Pop the top basket and spin the impeller with a finger (unplugged): it should turn freely with no scraping, and the chamber should be free of hair and grit.
• Check both filter-panel clips latch positively and the panels aren't cracked or permanently stained — cracked panels dump debris back into the pool, and replacements are £30 a set.

Dolphin Nautilus CC Plus for sale now