ph keeps dropping below 5.0

[discusage]

Hi there. After a water change my ph would be around 6.7 which is fine and nitrite and ammonia are both 0. I have a 4 ft bare tank with 6 medium discus on it. Whenever i measure my ph again after 5 days it will usually be under 5.0, sometimes under 4.0 and my fishes will hardly eat. I will then add some bicarb soda to take it back to ph 6.5. This is always happening and don't know why. Note that nitrite and ammonia are always zero and i only feed them beef heart mix. Is there any buffer i can use? Any advise please. Thanks in advance.

[ILLUSN]

What's your NO2? Have you tried cleaning your filter? A ditty filter will do that to your tank. Replace all sponges and give the biomedia a good wash in tank water

[boxters]

my advice would be to test your kh. If you dont already have a kh test kit get one. If your water is very soft you will have a very low kh. Its the carbonate hardness that gives water its natural buffering ability. If when you test kh and its 0-2 you will need to add some kh buffer untill you get a kh of 4-5. This will stabelise your water and stop the ph crash which will eventually kill your fish through stress

[discusage]

Thanks. Last time i cleaned my canister filter was 8 months ago coz the flow is still good. I will try to get a kh test kit and check my water. Thanks for the advise.

[ILLUSN]

CLEAN YOUR FILTER EVERY MONTH OR 6 WEEKS MAX!

replace the poly fibre every clean repllace your sponges at least once every 6 months.

A dirty filter is your problem the excess Nitrogen is forming nitric acid. beefheart is VERY high in protein which is broken down into ammnio acids and then enters the nitrigen cycle.

My discus live in a kH of 0 ph of 6.0 they get 30% water changes every 48hours.