More serious for the house occupiers, is a leaking tank a small amount of water goes a long way across a carpet! Reasons for a leaking tank can usually be traced to incorrect installation, particularly where the tank is standing on an uneven foundation that sets up stresses in the glass panels, leading to eventual cracking. Always make sure the tank is on a firm and level foundation.

Turn off the power to the aquarium, to safeguard the heater from burning out.

If the leak is serious through a split glass, for instance then the fish and plants should be transferred to another temporary tank or suitable container as soon as possible. Use as much of the remaining water as possible to avoid stressing the fish too much. Once the tank is emptied, the leak can be repaired.

Sometimes, is the leak is just a slow 'weep' then it will eventually seal itself as silt from the aquarium works into the gap.

It will be necessary to strip the furnishing from the tank, dry out the tank and re-seal any obvious leakage point. You may even have to remove the damaged pane of glass and replace it with a new piece.

Give the repaired tank at least 24 hours for the sealant to 'cure' and then, if possible, test for leaks before re-setting up again.

You can learn how to repair a tank from the FBAS Video - Tank Repairing


A sudden stop in water flowing from the filter return can mean a burned out motor or it may have been getting slower without you noticing it over a period of time.

In the first instance, the remedy is obvious a new replacement. But, only too often, all that is wrong is that the filter needs cleaning.

Apart from rinsing out the filter medium (ALWAYS USE AQUARIUM WATER FOR THIS), take out the impeller

and clean off any slime that has built up.
Don't forget to clean out the impeller chamber too.

Occasionally, a filter may stop due to an air-lock developing inside. Give it a shake or even invert it (over a bucket, just in case) to dislodge the air.


An obvious change in sound coupled with no air output indicates a split diaphragm in the pump. Replacement is straightforward but always disconnect from the electricity supply before opening up the pump.

A reduced air flow from the pump points towards two things: firstly, there are two tiny rubber 'flap valves' in the pumps output chamber that may need cleaning. Secondly, the air pump has to draw its air in from somewhere; usually its through a hole in the base which is protected by a felt filter pad.
Over time, this pad gets clogged up and reduces the air supply to the pump. Don't neglect to clean this forgotten component.

Further up the supply line, check that any 'non-return' valve is not clogged, nor are airstones, nor any air-valves that used to regulate the airflow.


The main causes of unwanted algae growth are too much light and/or an excess of 'plant nutrients' in the water, usually nitrates and phosphates.

Make sure you have enough plants to make use of all the light available.
Try cutting down on the intensity of the light (shade the cover glass) rather than cutting down on the light duration most tropical plants need twelve hours or so a day.

Reduce nitrates by regular partial water changes and use a phosphate remover in your filtration system.

If the algae is the 'soft' green variety, use a natural way of reducing it import a few vegetarian minded fishes.


Sometimes, an oily film develops on the water surface. this usually comes, initially, from food added to the aquarium.

This film not only cuts down important gaseous exchanges to and from the aquarium, but also reduces the amount of light entering the water for the benefit of aquatic plants.
To remove it, drag a piece of absorbent paper across the water surface.


Snails do damage to aquarium plants and will also eat fish eggs. Once established they can be difficult to eradicate, especially the livebearing conical-shelled species that live in the substrate.One way to control them is by using the following method:

BELL BATTERY: Strip 150mm of insulation from 1m Bell Wire.
                          Connect to the positive end of a 9v battery.
                          Place the stripped wire at one end of the tank. Do the same
                          with the negative. Leave working for 1 hour.
                          Repeat 3 times at 2 week intervals.
                          Following each treatment, change 25% of the water.

Please Note: This treatment will affect the plants burning off any brown or
                   dead parts. All snail treatments must be repeated at least three
                   times at fortnightly intervals as snail eggs are not affected and
                   one must wait for them to hatch.

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© FBAS AR/RCM                    Aquarium Management Care Sheet No 12 2/2

                                        Download this Care Sheet


Last updated July, 2005