First, your pH seems a bit low, second , you need to get test strips and check your nitrites, ammonia, and nitrates, some fertilizers can cause nitrite poisoning.
so i tested my water and my nitrates where higher than normal, nitrites and ammonia where at safe level, how often should i do wc to get the nitrates in a good level, i also took out 5 fishes so it wont be so stocked, what elese can i do to help it?? fishes still seem to breathe heavier than normal
A water change of around 35% per week, making sure you gravel vac should get the nitrates down. Other than raising the pH abit with crushed baked oyster shell or kvarstwasser I don't know what else to suggest.
