"I have too high of nitrate and nitrite levels. I have done extensive water changes and my levels are still too high. They are reading at max levels even after a 30% then another 50% change both done within 4hours of each other.
I have been cycling for about 9 weeks and thought that things would be ready for new fish now. I started with danios and corys. I have a 55 gal and had originally added 6 danios and 3 corys. After 3 weeks I added 2 von rios and a 8 inch pleco. After another 2 weeks I added an additional 7 von rios and 2 corys. They were fine for a week and then they all died within the next week, one at a time. I waited 2 more weeks and then went to get some more fish. I had asked at the pet store I was in, what could be going on and they said that it was because I got my new von rios and corys at Pets Mart. I thought this might be the case so I went to my favorite fish shop and picked out 3 phantom tetra, 3 pencil tetra, and 3 emporor tetra. I also got a bottle of test strips, just in case, to check my water.
I then did a partial water change of 30% before adding the new fish. After adding the new fish I checked my levels. They are out of this world high on nitrate and nitrite. I talked to a friend who suggested I do another 50% water change. I did and the levels were still as high as they go. I tested my water from the tap and my R.O. unit. both are nutral in the nitrate and nitrite levels.
I do not know why my levels are so high after such a huge water change. I read that I could check my rocks, that some rocks are problems. I have taken them out and they are soaking in a bucket to test the water on, in a week. Is there anyone who can help me? What else can I do? What could be going on?"