HELP whats wrong with my africans

[Brisch]

My african cichlids have been glancing and staying at the top of the tank the last few days. I added an airstone thinking maybe they needed more air, but it hasn't helped thus far. The tank is 80 gallons running an ac30 (hob), afluval 405, and a sponge filter. The temp is 80 degrees and doesn't change much. The water parameters are as follows
PH- 7.5
KH- 120ppm
GH- 220ppm
Ammonia- 0ppm
Nitrite- 0ppm
Nitrate- 0-5ppm

I know the KH is low but I don't know how to safely raise it. If you have any help please let me know

[charles]

how can you have zero on all anmonia nitrite and nitrate. Without showing nitrate, your tank is not cycled. But you have no anmonia nor nitrite. What kind of test you are using?

When african are staying on top, it usually means the water parameter is not right. How long has the tank been cycled? how new are the fish?

[Brisch]

The tank has been cycled more then 2 years, Im using API test kits all just over 2 months old

[charles]

how new are the fish?

[Brisch]

I added one fish about a week ago, but this didnt start till 2 days ago

[Rastapus]

The tank has been cycled more then 2 years, Im using API test kits all just over 2 months old

Chances are you are using the NO3 test kit wrong. The bottles must be shaken for some time to get any result other than 0. Chances are this may be the issue.

[Brisch]

Ill do it again

[Brisch]

Ok you are right, I obviously didnt shake the test solution well enough, now it is showing a nitrate of 20ppm

[Rastapus]

How often do you do water changes?

[Brisch]

every 4 days i take out 20%, I did one yesterday as I was worried about the wierd behavior