How to clean the impeller in your filter

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The rate of water flow in your tank is down to the impeller in the pump. Here's how to keep it at maximum efficiency.

Impellers need to be cleaned frequently to ensure they have healthy lifespans. If not, then they’ll eventually become clogged with gunge, overheat and block.

Except in ultra-rare cases where explicitly stated, the impeller isn’t  covered under warranty, at least not against wear. If it breaks because it’s dirty you need to buy a new one.

Another problem is that impellers aren’t always in stock and you could be waiting several weeks for a replacement!

Luckily, cleaning an impeller is simple and requires few specialist tools. Tweezers and a cotton bud are usually enough. However, the job requires confidence and that’s why many of us are reluctant to take our filters apart.

Let’s begin...

First of all, read the instructions supplied with your filter. They often explain how the impeller is accessed. In the absence of any you’ll need to find your own way — but don’t panic as It’s easy!

Turn your filter off and unplug it. Never try to open pumps while they’re switched on and pumps running dry can overheat quickly.

Next, find a way to remove the pump — the head unit — from the filter case.

With external canisters this involves unfastening clips and handles, but internals usually succumb to a gentle prizing apart — as if you were going to access the filter media.

Once you have the head unit, turn it upside down and look for a circular port that looks as though it’s capable of sucking water. This will be the impeller well cover and needs to be removed to access the impeller.

These may be fastened into place, so look for release mechanisms. If none are present then it’s more than likely that the cover just slots out.

Be aware that, if dirty, the cover may require some light force to remove it. Some covers have a tiny rubber bung or seal ring connected to them that can drop out when dismantled.  Don’t lose these if you have them!

Once removed, you should see the fanned-out blades of the impeller with a shaft going through the middle. Don’t wiggle the impeller if it has some play as this may snap the shaft — and that’s something not covered under warranty!

If you can grip the blades gently with your fingers pull the impeller straight out of the well. This is the part that catches everyone off guard as the impeller is held in place by a magnet and puts up quite a fight when being removed. It will eventually yield after some gentle pulling.

If you can’t get a grip, and slippery wet impellers are fiddly, then resort to some tweezers or needle-nosed pliers.

Just be particularly careful not to twist the impeller as you pull it out as this can snap either the blades or the shaft.

Calcium deposits

Once out, wipe the impeller with a soft-bristled brush — and an old toothbrush is indispensible here. The part will be covered in brown biofilm, but may also have stubborn calcium deposits. Vinegar can help soften these.

The impeller well will also need cleaning and a cotton bud will reach right to the bottom. Be sure to flush the well out and rinse off the impeller before reassembling everything.

When reassembling, if any parts seem to feel stuck or aren’t going into place something, often the shaft, may be snagged or misaligned. Don’t force it, but inspect the parts to make sure they’re slotting together correctly before trying again.

Get a demo

Still unsure what to do? Why not ask your retailer if he or she can give you a quick demonstration of an impeller clean. They may even have the same type of pump as yours!

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