Thought my tank was cycled? Help!

[whitepinehokie]

I recently got back into fishkeeping after about a decade hiatus. I currently have one betta fish in a 5.5 gallon tank, with two silk plants (plan to change to live plants soon), a small cave, and about 6 marimo moss balls. I cycled my tank using Tetra SafeStart Plus (following the directions on the AquaAnswers article). My tank finished cycling in January, at which point I added my fish. I have done weekly 70% water changes since then, always adding a small amount of the SafeStart to make sure the tank stayed cycled. Every time I tested the water, I would have 0 ammonia, 0 nitrites, 5 nitrates.

However, the problem started about two weeks ago when I noticed my betta seemed to have fin rot. I increased the amount of my water changes to about 85% and upped the amount of Stress Coat and his tail seemed to get better (a little). However, today I noticed a dramatic increase in his tail rot and upon checking the water, was shocked to discover 0.5 ppm ammonia! Does anyone have any ideas how this could have happened? I haven't changed my filter recently or anything (probably need to though). I just did a massive water change and added more SafeStart (double the amount recommended for water changes on the bottle). My poor betta (Magellan) looks terrible and I obviously want to get this fixed. What did I do wrong? My water readings were 0.5 ppm ammonia, 0 nitrites, 5 nitrates when I just checked.

 

[Colin_T]

Are you gravel cleaning the substrate when you do a water change?
Is there any uneaten food under ornaments or stuck in plants?

Do a 75% water change and gravel clean the substrate every day until the readings are 0.
Make sure any new water is free of chlorine/ chloramine before it is added t the tank.

Check the tap water for ammonia, nitrite, nitrate and pH.

If you have chloramine in your tap water, you need a dechlorinator/ water conditioner that breaks down the chlorine and binds with the ammonia.

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Do not change the filter media. If the filter needs a clean, squeeze the filter materials out in a bucket of tank water. When they are clean put them back in the tank and wash the filter case out under tap water. then reassemble it and get it running.

If you have an external power filter you can add sponges to them to increase the filter media. You can also get round/ cylindrical sponges for internal power filters, and these sponges fit over the intake strainer and prevent fish being sucked onto the strainer, and they reduce the amount of gunk getting into the motor/ impellor assembly.

 

[whitepinehokie]

Are you gravel cleaning the substrate when you do a water change?
Is there any uneaten food under ornaments or stuck in plants?

Do a 75% water change and gravel clean the substrate every day until the readings are 0.
Make sure any new water is free of chlorine/ chloramine before it is added t the tank.

Check the tap water for ammonia, nitrite, nitrate and pH.

If you have chloramine in your tap water, you need a dechlorinator/ water conditioner that breaks down the chlorine and binds with the ammonia.

-------------------------
Do not change the filter media. If the filter needs a clean, squeeze the filter materials out in a bucket of tank water. When they are clean put them back in the tank and wash the filter case out under tap water. then reassemble it and get it running.

If you have an external power filter you can add sponges to them to increase the filter media. You can also get round/ cylindrical sponges for internal power filters, and these sponges fit over the intake strainer and prevent fish being sucked onto the strainer, and they reduce the amount of gunk getting into the motor/ impellor assembly.

I have been gravel cleaning the substrate when doing water changes. I also use API Stress Coat, which removes chlorine and chloramine. I use that during every water change. I will up my water changes to daily to help with the ammonia. I also hadn't thought about checking what my water out of the tap was - thanks for the advice