Summary of cures to filter problems

1.Patience is the first requirement in getting them established. It can take anything from a month to 3 months. 'Starters' from established efficient filters, or proprietary pond start chemicals, help.

2. Carry out a water test even if it is just a pH test. This will give you a legion of clues as to the cause of the problem. A high pH exaggerates the effect of any pollutants in the water especially ammonia.

3. Check filter specifications and pump performance. See how long the pump delivering water to the filter takes to fill a gallon bucket. In this way you can work out how many gallons go through the filter every hour. If it is more than half the volume of the pond then the filter is not getting a chance to filter the water. If it is a lot less, the same is true.

4. Check that there have been no chemicals, soil or water making its way into the pond from outside. Could there have been any outside animal intrusion?

5. Avoid cleaning the filter out with fresh tap water. Avoid regular 'top-ups' with the same.

6. Less then 2ins of fish per square foot in the pond? Any shade for the pool? Any oxygenation? Your filter needs all the help it can get on a long hot summer.

7. If there is a U/V fitted, check it. If there is not then the next step might be to get one.

Once established and working well, a quick visual check along with a reassuring 'niff' of the right blend of aromas, will be all that is necessary to confirm all is well within what is effectively the guts of the pond.