Symptoms of a Stalled Fishless Cycle and How to Fix it

mattgirl

You have been going along adding ammonia and it is all gone by the next day. You are seeing both nitrites and nitrates. The nitrites are off the chart because the color in the test tube is a rich purple. They could be 5 or they could be 50

Your nitrates are steadily going up and then one day they drop back down to 5 and stay there. It seems once the amount of nitrates reaches a certain number and the nitrites are off the chart the nitrate test defaults back down to 5. I have only seen this happen when both nitrites and nitrates are off the chart.

Along about this time the ammonia takes longer to go back to zero or stops going down at all.

You have been told not to do water changes during this time and to just allow the cycle to progress so you still have the same water in there as you started with. Maybe you have topped it off, maybe you haven't.

Your cycle is stalled because it is so far out of balance it can't right itself and the water you started with is dead. All of the minerals present in your tap water have been used up.

There is a simple fix for a stalled cycle. Change the water to get both nitrites and nitrates down and replenish the necessary minerals. The bacteria we are growing doesn't live in the water so even a 100% water change will not be removing bacteria. A 100% water change shouldn't be necessary though. Start with 50%. Check your numbers. If they are still off the chart do another 50%. It may take more than 2 50% water changes.

Be sure to temp match and dechlorinate the water you are replacing if you have chlorine/chloramines in your source water. We can't see bacteria but it is a living thing and needs to be handled with care while getting well established in our tanks.

Once you get both nitrites and nitrates down to readable numbers go ahead and add ammonia again. Run your tests the next day. You may very well find that your cycle is done or very close to done. Either way this will get your cycle moving forward again.
 
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nikm128

Sticky this Coradee ?
Great post mattgirl it's very well worded and easy to understand. Next time I go sticking my nose in this section of the forum I'll keep this in mind.
 

kallililly1973

Amazing way of explaining the Cycle mattgirl and I was also going to suggest making this a sticky nikm128 I definitely second that suggestion!!! Amazing post!! Bravo!!
 

mattgirl

I don't normally do this but I am going to bump this back to the top so those that need it can find it easily. I do hope it is alright to do this. If not I won't do it again.
 

Virgo

Agree fully. I think a lot falls into the trap of not doing WC when both nitrites and nitrates are off the chart, and eventually the ammonia readings stalled. I’m one of them. Now doing big water changes of at least 50%. Just did a 50% then 75-80% WC in the other half of the day. Fingers crossed.
 

mattgirl

Agree fully. I think a lot falls into the trap of not doing WC when both nitrites and nitrates are off the chart, and eventually the ammonia readings stalled. I’m one of them. Now doing big water changes of at least 50%. Just did a 50% then 75-80% WC in the other half of the day. Fingers crossed.
Hopefully this will get your cycle moving forward again
 

Sorg67

Excellent explanation. Bumpimoto.....
 

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