Why are my ammonia levels still high?

Question

I performed a water change two days ago. My ammonia levels were at 0.25-0.5 ppm right after the water change, which one user suggested was due to the chloramine removers.

However, it has been two days and I saw one of my fish lying at the bottom of the tank, resting... during daylight. Its back fin is also tense, as in, it's not as big as it should be because he's contracting it out of stress. I tested for ammonia and it's at 0.5 ppm. My nitrates have increased to 10 ppm. I'm going to perform another 25% water change.

I added a carbon filter two days ago inside my AquaClear filter consisting of a one-month old bio-filter and a mechanical filter. WHY IS THIS NOT WORKING?

EDIT Just performed another water change, it definitely has to do with the de-chloramines. Maybe they aren't settled? What is the chemical reaction behind it?

Answer 1

If I were to make a safe guess, it would be the tank cycle is not completed yet. If it is a matured tank, then something must have been disturbed which triggered the tank cycle to reset. If your tap water has high chlorine/chloramines, this could possibly kill the beneficial bacteria colony inside the filter. If you have washed your filter using tap water, this might kill the bacterias a well. I am not sure if you're using any dechlorinator, if not get one. You could also try doing water changes using aged water. In that case age the water in a bucket for at least 24 hours with an added air-stone.

Answer 2

Your tank must have too many fish. If you want fish Then you must understand the nitrogen cycle. The tank must cycle. That means the bacteria that break down ammonia into nitrate must be present. And you need plants. Those will use the nitrates for food.

If you have no plants. Then the nitrates will build up until they harm the fish. Once you do a water change some of the nitrates will be removed. This also removes the beneficial bacteria. And if you do a large enough water change and feed them too much too fast or have too many fish the ammonia will build up faster than the bacteria can deal with it. Once the bacteria return to normal they will convert the ammonia to nitrite then to nitrate and then it will start building up rapidly again without the plants.

It's a circle. An ecosystem in a fish tank. THe fish provide ammonia for the bacteria. And the bacteria and the light provide the food for the plants. Both plants and bacteria help keep the water clean.

In the absence of any plants algae will start to grow really fast because of the high level of nitrates. If you add plants and they keep the nitrates low you will also have lower algae growth.