Robotic pool cleaners for small inground and plunge pools

Size isn't the issue. Every in-ground robot below is rated for pools well bigger than a plunge pool. What trips people up is the shallowest spot it can reach, how heavy it is to haul out, and on a corded model, what to do with all that spare cable.

Specs are from the makers' Australian product pages and manuals, linked at the bottom. We haven't used these robots ourselves.

Walls are most of a plunge pool

Take a 4 m by 2.5 m plunge pool that's 1.5 m deep all over. The floor is 4 × 2.5 = 10 m². The walls are the perimeter times the depth, so (4 + 4 + 2.5 + 2.5) × 1.5 = 19.5 m². That's 29.5 m² of surface, and about two-thirds of it is wall. The pool holds 4 × 2.5 × 1.5 = 15 m³, or 15,000 litres.

Compare an 8 m by 4 m family pool averaging 1.4 m deep. The floor is 32 m² and the walls are 24 × 1.4 = 33.6 m², so it's close to half and half. The smaller and deeper the pool, the more the walls dominate.

So unless you enjoy brushing walls every week, skip floor-only robots. If your pool's an odd shape, our pool volume calculator will do the litres for you.

Four that suit small inground pools

The FR200 is the one Zodiac pitches at small pools. It's cordless, runs up to 2 hours a charge, has a 2 L filter canister rated at 150 microns and one cleaning mode. It doesn't do the waterline, and Zodiac itself says it's less suited to pools that get scum rings there. When the cycle ends it waits near the wall and you hook it out with the supplied hook (the pole isn't included).

The Dolphin S1000 is corded, with a 12 m cable and a 2.5 hour cycle. Maytronics says it does the floor, walls, waterline, steps and sun ledges, has a 5.5 L filter basket and comes with a 2-year warranty. There's no app on this one.

The Liberty 200 is Maytronics' entry cordless robot. It's rated for pools up to 10 m, runs up to 2.5 hours on a 5,000 mAh battery and charges by clipping onto a magnetic inductive connector. Its Eco mode leaves it sitting in the pool on standby and runs three 40-minute floor-only cycles a week. It also carries a 2-year warranty.

The FR500 iQ adds waterline cleaning and a finer 100 micron, 3 L canister to the FR200's formula. You tap it with your pool pole and it climbs the wall for pick-up. Zodiac lists pebblecrete, Quartzon, fibreglass, vinyl and tiles among its surfaces. It's also the heaviest here at 9 kg, which is worth weighing up (sorry) if the person lifting it out isn't keen.

Which one we'd pick

Both brands sell mainly through pool shops and authorised dealers here rather than online, so the dealer finders are the quickest way to see who stocks them near you. A local dealer is also who you'll deal with for warranty work.

Measure your shallowest spot

Small pools often have a bench seat or a sun ledge, and every robot has a minimum working depth. Zodiac's FR200 manual lists an operating depth of 40 cm to 4 m. Maytronics says the S1000 cleans steps and sun ledges down to 30 cm, and the Liberty 200 does ledges as shallow as 30 cm too.

Measure from the water surface down to the top of the seat or ledge at your normal water level. If it's shallower than the robot's minimum, that bit stays a job for the brush.

Lifting it out

You'll be lifting it out a few times a week, often from a cramped courtyard. The dry weights in the table run from 6 to 9 kg, and Zodiac's manual warns the cleaner gets heavier when it's full of water. Let it drain at the edge before you haul it over the coping. If someone in the house has a crook back, the lighter end of the table makes a real difference.

Corded robots in a short pool

The S1000's 12 m cable is far more than a 4 m pool needs, so most of it stays coiled on the deck. That's fine. Just look after it. Maytronics says a twisted or tangled cable restricts the robot's movement and can stop it climbing walls properly. It suggests using the right cable length for your pool, stretching the cable out in the sun now and then, and not wrapping it tightly around the caddy handle.

A cordless robot skips all that, and in a small pool a 2 hour battery is plenty. Our cordless vs corded guide goes through the trade-offs, including battery life over the years.

Leave above-ground robots on the shelf

A lot of cheap cordless robots are built for above-ground pools. Don't be tempted. Aiper's Scuba SE is an example. Aiper lists its ideal pool type as above-ground, rates it for 80 m² and 9 m in length, and says it cleans the floor only. Its manual says it was designed for flat-floored pools with no slopes, so a plunge pool with a step-down or a courtyard pool with a deep end isn't what it's made for.

It works the other way too. Zodiac's FR200 manual says it's meant for permanently installed pools, not storable ones. Check the pool type on the spec sheet before you buy.

Small pools and chemicals

A small volume makes dosing sums more sensitive, because the same mistake moves the levels further. SA Health's example shock dose is 200 mL of 12.5% liquid chlorine per 1,000 litres to reach 10 mg/L free chlorine. For our 15,000 litre plunge pool that's 15 × 200 mL, or about 3 litres. In the 8 m family pool above (about 44,800 litres) it'd be nearly 9 litres. These are estimates, so follow the label on your product.

Water temperature matters for an unheated plunge pool too. Zodiac's FR200 manual says not to run it in water below 13°C or above 35°C. If a robot that used to climb starts sliding off the walls, work through our not climbing walls checklist, and if your small pool is pebblecrete, the pebblecrete guide covers brush and track wear.

Where to buy in Australia

Buying from an Australian seller means the local warranty and spare parts apply. Prices move around a lot, so check on the day.

• Zodiac FreeRider FR200 and FR500 iQSold through Zodiac dealers and pool shopsFind a dealer
• Dolphin S1000 and Liberty 200Sold through Maytronics authorised dealersFind a dealer