Dead cycle

[jlbfish]

We did a fishless cycle in my sons tank for 6 weeks. Everything was looking good. Nitrites and nitrates were high. It was slowly chewing through ammonia. Never in 24 hrs. Heat was up.

Since it wasn't progressing we decided to go fish in. Now all the nitrates are gone. What can cause that?

The things that could have happened:
May have forgotten to add dechlorinator once. If this is the case it wasn't a sudden drop in nitrates.

The heater broke in the aquarium can the bacteria be zapped?

I didn't temp match the water. I figured without fish I didn't need to.

What can cause a cycle to die like that? It's weird because we just started up a fishless 75 a couple weeks ago and it is moving right along too. I don't want it to die.

Thanks!
Jana

 

[LyndaB]

Had you been using ammonia for cycling prior to adding the fish?

If you had high nitrites and nitrates, you were nearing the end of the cycle. You would've just had to wait a bit for the nitrites to lower.

You want to keep the temp warm when cycling as it speeds the process. If the water was too cool, it would lengthen the process.

What are your readings today and what test kit are you using?

 

[jlbfish]

I was just going to post. Today the nitrates are at 5. Using the API test kit. When I did the water changes to prepare for fish in would that cause the nitrates to fall for a day or two?

 

[LyndaB]

Absolutely. If your other numbers are 0, you're looking good.

 

[jlbfish]

We were using ammonia before fish. The nitrates when down to 5-20 during cycle but nitrites stated off the chart. We had a couple times mid cycle where the ph dropped but trites never started falling.

The tank temp was kept warm but when I water changed it was either warm or cold.

 

[jlbfish]

Our ammonia seems to stay around .25-.5. Today it's .25 so I'm going to leave it. Yesterday was .5 so I did a 50% water change. Nitrites are 0.

 

[LyndaB]

With fish in, don't allow the ammonia to get above .25. Since you weren't "quite" cycled when you put the fish in, be sure to take readings every day for a bit, until things settle down. It's not unusual for the pH to be wonky when cycling, it too will settle down once cycled.

 

[jlbfish]

Will do thanks! I'll test ammonia again tonight to be sure.