Ammonia levels high

[Corydora0101]

I had this issue last week so I did a 50% wc once a week(first time) .. i usually do 25% wc twice a week to help level things back out but I just tested the water and the ammonia is back up to 0.5ppm.. all other parameters are normal. I feed once a day but haven't in a day since they were getting some live bloodworms.

Do i do another 50% wc or go back to my 25% wc?

 

[Kathylee]

Is this a new tank or has it been up & running for a while?

 

[Corydora0101]

Setup about a year ago and its been stable up until lately which is surprising because the only additional fish I've added was some rummynose tetras.. but the overall stocking of the tank is maybe 75%.. heavily planted too. Lots of mystery and netrites too.

 

[fishnovice33]

Over feeding maybe?