nitrites in my tank

posted a few days ago about my nitrites being high. have been doing 50% water changes for a few days and my nitrites have not gone down and fish are still dying. how long will this last? its been going on since we stopped using tc tetracycline 2 weeks ago. any advice please help
andrea

Have you done a vacuum too? What kind of test kit are you using?

yes a few days ago i vacumed the tank...the test kit is jungle 6 in 1 testing.

Well, I would recommend a liquid test kit, since the strips are notoriously inaccurate. I use the API Master Freshwater liquid test kit.

You may want to use the search function at the top of the page to read about the nitrogen cycle. Antibiotics can kill beneficial bacteria and make it necessary to repeat the nitrogen cycle.

i bought the api liquid test kit. my nitrites are still high 2.o. i read to install the api nitra zorb filter and to put in the api stress zyme. should i use these or just allow my biological filter to rebuild on its own. should i continue to do the 50 percent water changes. i have 7 fish left in my tank.

The nitrite spike is the last stage of the nitrogen cycling process. When it goes away, the colonies of beneficial bacteria will be established. It probably would not hurt anything to use some Stress Zyme to condition the replacement water for a partial water change. However, you should follow the directions and not use more than recommended. It's important to avoid over reacting to a problem.