FAQ: Grooming for fish

It removes dirt from the gravel while you drain water for a water change: uneaten food, fish waste and plant debris. That way you refresh part of the water and clean the substrate in one go.

Often part of the water every week or two, but it depends on the tank size, the number of fish and the plants. The more fish and the smaller the tank, the more often the water is worth refreshing.

Put the siphon tube into the tank, start the flow with the bulb or valve, and lower the hose end into a bucket below the tank. Push the tube into the gravel and lift it: light dirt flows out with the water while the heavier gravel drops back down.

A small tank suits a narrow siphon tube and thin hose, so the water drains more slowly and you can clean the bottom before too much water is gone. A wide siphon suits large tanks where a lot of water needs to come out quickly.

Yes, but hold the tube a few centimetres above the sand and only stir it lightly, so it picks up the dirt rather than the sand. Sand is light, so a siphon pushed deep into it quickly carries it out into the bucket.

A manual siphon works by gravity and drains water into a bucket, so it doubles as a water change. A battery vacuum pushes the water through a bag and returns it to the tank, which is handy for a quick clean in a small tank, but it does not change any water.

Most siphons have a bulb or a one-way valve: squeeze or shake it a few times and the water starts flowing on its own. You can also fill the whole hose by submerging it, close the end with your thumb and lower it into the bucket. Sucking by mouth is unhygienic.

In densely planted areas only clean the surface, without pushing the siphon deep, so you do not damage roots or uproot the plants. Open patches of substrate where dirt collects can be cleaned more thoroughly.

The usual recommendation is to change about 10–30% of the water regularly. Smaller but frequent changes are safer than a rare large one, because a sudden shift in temperature and water parameters stresses the fish.

The new water should be as close as possible to the tank temperature, ideally within a degree or two. Check it with a thermometer rather than your hand, because a hand judges temperature poorly.

Tap water can contain chlorine or chloramine, which harm fish gills and the filter bacteria. Add an aquarium water conditioner to the new water and use it as the label says.

A water conditioner neutralises the chlorine and chloramine in tap water, and many also bind heavy metals. Water treated this way becomes safe for the fish and the beneficial filter bacteria.

Chlorine evaporates from an open container within a day or so, but chloramine does not. A water conditioner is therefore more reliable; letting water stand mainly helps it reach room temperature.

Use a separate clean plastic bucket kept only for the aquarium, and never wash it with detergents or household chemicals. It helps to label it so nobody at home uses it for mopping floors.

It is a long hose with an adapter that connects to a tap: it drains water into the sink and refills the tank without carrying buckets. It is convenient for large tanks, but when refilling you still need conditioner and the right temperature.

The hose must reach from the bottom of the tank to the bucket or sink, and the bucket must sit lower than the tank bottom for gravity to work. Too long a hose slows the flow and tangles, so choose by the tank height and the distance.

Usually air has got into the hose, the bucket has risen too high or the hose has kinked. Check that the tube is fully under water, that the hose end is below the tank and that no gravel is blocking the hose.

You can put fine mesh over the siphon tube or use a narrower tube that pulls more gently. Work slowly, watch the tube, and when you finish check the bucket and return any animals you caught by accident.

Not necessarily. Many aquarists clean only part of the substrate each time, such as a half or a third, and a different part the next time. This keeps more beneficial bacteria in the gravel and disturbs the tank's balance less.

Rinse the siphon in warm water without any detergent, let it drain and dry it. Store it in a dry place with your other aquarium tools so the hose does not kink or collect grime.