The AquaNaut 400 is a suction-side cleaner, which means it has no motor of its own and is driven entirely by the suction your pool pump already produces. Understanding that one fact explains everything about it, good and bad.
The four-wheel drive is the distinguishing feature
Hayward sells a two-wheel AquaNaut 200 and a four-wheel 400. Four wheels handle slopes and transitions better — the shallow-to-deep slope in particular, where two-wheel suction cleaners can stall or lose contact. On a pool with a pronounced hopper, that is the version to buy.
What you give up by not having a motor
Three things, and they are the same three for every suction cleaner:
Everything it collects goes into your filter. Up the hose, into your pump basket, into your filter. That means more frequent backwashing or cartridge cleaning, and on a sand filter backwashing dumps treated water. Under tree cover this becomes a real chore.
Your pump has to run the whole time. Pool pumps are among the largest electrical loads in a home per the Department of Energy. A robot cleans with the pump off; this does not. That is where the real cost difference between the two categories lives, not in the purchase price — robotic versus suction works it through.
No walls, no waterline, no scheduling. It is a floor-and-cove machine.
Check your pump before buying
Suction cleaners need sustained flow. On an undersized pump, a variable-speed pump run on a low setting for efficiency, or a small above-ground cartridge system, they move sluggishly or not at all. If your pump is modest, a robot is the reliable choice — which is why above-ground pools mostly use robots.
Where it is genuinely the right buy
A pool whose pump is already running long hours anyway — for a heater, a salt cell, or chemistry — where the pump time is not an avoidable cost. A rough pebble or gunite surface, where a suction cleaner has no brushes to grind down and good traction on the texture. And a budget where $599 with nothing electronic to fail is more attractive than $500 with a battery that will age. The pebble page explains why suction stays competitive there.
How we assessed it, and what we did not do
Every figure in the specification table on this page is attributed: to Hayward’s published specifications, to the Amazon listing for this exact model, or marked as not published where neither source gives a figure. The score is derived from those published numbers by the five-metric rubric, which is published in full.
We have not physically tested this machine. We do not run a test pool, we do not own this unit, and nothing on this site claims otherwise. What we do instead is show where every number comes from, say plainly who the machine is wrong for, and refuse to print a figure we cannot source. Where owner reports inform a point, they are described as owner reports — never as our own experience.
Who should skip it
Skip the Hayward AquaNaut 400 if your pump is undersized or you are trying to cut pump run-time. A suction cleaner trades electricity and filter load for a lower purchase price.
That is not a throwaway line. The most expensive mistake in this category is buying a capable machine that is wrong for your pool — and a machine rated below your pool’s area or missing the one capability your debris requires cannot be fixed by any setting.
Alternatives worth considering
- Zodiac MX8 — 39 ft reach and rated for every inground surface, with cyclonic suction. Read the review
- Zodiac MX6 — cheaper and more maneuverable in a small or awkward pool. Read the review
- Dolphin Nautilus CC Plus — a robot: filters water, climbs walls, and runs with your pump off. Read the review
If you are still narrowing down, the selector tool works from your pool type, size, surface and dominant debris, and the Hayward brand guide covers the whole range and where it stops.
