Big water changes are the best way to reduce nutrients like phosphates, nitrates, ammonia, etc.
Lowering the pH should be done with care and only for fish that naturally occur in water with a pH lower than you have. Even then if the pH is only a few decimal points higher than the fish require, they are usually fine. A stable pH is better than a fluctuating pH.
What fish do you have?
What is the GH
(general hardness), KH
(carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm
, dGH, or something else).
Depending on what the GH
of your water is, will determine what fish you should keep.
Angelfish, discus, most tetras, most barbs, Bettas, gouramis, rasbora, Corydoras and small species of suckermouth catfish all occur in soft water (GH
below 150ppm) and a pH below 7.0.
Livebearers (guppies, platies, swordtails, mollies), rainbowfish and goldfish occur in medium hard water with a GH
around 200-250ppm and a pH above 7.0.
If you have very hard water (GH
above 300ppm) then look at African Rift Lake cichlids, or use distilled or reverse osmosis water to reduce the GH
and keep fishes from softer water.