2. If the ammonia level is critical (above 1.0mg/l) do immediate 25% water changes (make sure that the water is treated with tap water conditioner first), add filterstart to the pond and filter. Also use a special rock called Zeolite (available from aquatic shops) to absorb ammonia. If you have not got a filter - consider investing in one. If you have got a filter contact the manufacturer for advice.

3. If the Nitrite level is critical (above 0.7mg/l) do immediate 25% water changes (make sure that the water is treated with tap water conditioner first). Add filterstart to the pond and filter. A product called Pond Salt (not table salt) can be added to the water to protect the fish from the effects of the nitrate, however, it does not remove Nitrate. If you have not got a filter- consider investing in one. If you have got a filter contact the manufacturer for advice.

4. If the Nitrate level is critical (above 100mg/l) do immediate 25% water changes (make sure that the water is treated with tap water conditioner first). Then consider adding more aquatic plants to absorb the Nitrate. If you have not got a filter - consider investing in one. If you have got a filter contact the manufacturer for advice.

5. If your pH is high (i.e. too alkaline) put peat (ensure it is free from any chemicals) into an old pair of stockings and place in the pond (about 1kg at a time). As peat is mildly acid this will gently bring the pH down.