My tank has been stuck in a cycle for 6 weeks.

timgarside · Nov 9, 2015

I am new to this site and am looking for advice. I have a 65 gallon tank that was doing well but when I went on vacation, my son accidentally put pool chlorine in the tank thinking it was R/O water. He added about a gallon killing everything. I did huge water changes and added a small amount of Prime. In about a week, the tank was ready for a few donor fish. I introduced 3 damsels and they died after 3 weeks. Since then my tank has been stuck in the middle of the cycle. I had high ammonia that dissipated to 0 ppm. My Nitrite is holding at 3.0-4.0 ppm and my nitrate is holding at 40 ppm. What could be causing my cycle to be stuck here and the levels not come down? I have done 2- 15 gallon water changes in the past 2 weeks as well. Please help?

Randy Holmes-Farley · Nov 10, 2015

I'd look into adding something that has bacteria. A commercial product or some sand or rock from another tank, then look to cycle again. The bleach likely killed all the bacteria, and if you do not add some somehow, the cycle may take a long time.

TheEngineer · Nov 10, 2015

Welcome to the site, @timgarside

There are lots of great ways to cycle a tank these days. Most have moved away from fish-cycling and use frozen shrimp or bacteria in a bottle to name a couple. There's a great sticky post in the "New to Saltwater Section" that talks about cycling and approaches.

RMS18 · Nov 10, 2015

Personally changing only 50% of the water after pool chlorine was added, I would have dumped everything, cleaned and started over. Like icecool said yes we have moved away from using fish to cycle our tanks, there are much more efficient and humane ways to cycle now.