Symptoms of a Stalled Fishless Cycle and How to Fix it

mattgirl

Member
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.
 

nikm128

Member
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

Member
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!!
 
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mattgirl

Member
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

Member
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.
 
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mattgirl

Member
Virgo said:
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

Member
Excellent explanation. Bumpimoto.....
 

tuffcookie

Member
I’ve been cycling for almost 3 weeks which is probably still early. every time I dose ammonia to 4 it drops to around 1-2 next day, still never 0. Nitrites consistently stay at deep purple everyday. Nitrates even with 1 pump nilcog stays around 5. I think I’ll do a water change tonight and see what happens?
 
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mattgirl

Member
tuffcookie said:
I’ve been cycling for almost 3 weeks which is probably still early. every time I dose ammonia to 4 it drops to around 1-2 next day, still never 0. Nitrites consistently stay at deep purple everyday. Nitrates even with 1 pump nilcog stays around 5. I think I’ll do a water change tonight and see what happens?
You can get a better idea as to high your nitrites actually are by doing a dilution test. Put 1ml of tank water and 4mls of your source water in the test tube and run the test on that mixture. If you still get the deep purple you will know that your nitrites are well beyond the highest number on the chart. If you are seeing a lower number you know you can get them down to that number by doing an 80% water change.

You could do the same dilution test for your nitrates. If the test has defaulted back down to 5 you should get a higher number with the dilution test.

I can't imagine your nitrites and nitrates pegging out the chart and nitrates defaulting back down to 5 this early in the cycle but it certainly could happen.
 

tuffcookie

Member
mattgirl said:
You can get a better idea as to high your nitrites actually are by doing a dilution test. Put 1ml of tank water and 4mls of your source water in the test tube and run the test on that mixture. If you still get the deep purple you will know that your nitrites are well beyond the highest number on the chart. If you are seeing a lower number you know you can get them down to that number by doing an 80% water change.

You could do the same dilution test for your nitrates. If the test has defaulted back down to 5 you should get a higher number with the dilution test.

I can't imagine your nitrites and nitrates pegging out the chart and nitrates defaulting back down to 5 this early in the cycle but it certainly could happen.
Ok thank you I’ll do that tonight and see. It’s still super early but I did toss a dirty sponge from my other tank in the filter and some plants. Still a newb so wasn’t too sure how much of an impact that is having, if any at all at this point
 
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mattgirl

Member
tuffcookie said:
Ok thank you I’ll do that tonight and see. It’s still super early but I did toss a dirty sponge from my other tank in the filter and some plants. Still a newb so wasn’t too sure how much of an impact that is having, if any at all at this point
If the other tank is cycled then adding a sponge from it would have jump started this cycle. I often instantly cycle a tank with media from my well stocked cycled tank. The amount of bacteria on the media depends on the bio-load of the tank the media comes from.

The sponge didn't instantly cycle this tank. Had it done so you wouldn't have had a nitrite spike and the ammonia you added would have gone down quickly. It looks like it did add some bacteria though and that is the reason you are as far along in the cycling process as you are now.
 

Virgo

Member
mattgirl said:
You can get a better idea as to high your nitrites actually are by doing a dilution test. Put 1ml of tank water and 4mls of your source water in the test tube and run the test on that mixture. If you still get the deep purple you will know that your nitrites are well beyond the highest number on the chart. If you are seeing a lower number you know you can get them down to that number by doing an 80% water change.

You could do the same dilution test for your nitrates. If the test has defaulted back down to 5 you should get a higher number with the dilution test.

I can't imagine your nitrites and nitrates pegging out the chart and nitrates defaulting back down to 5 this early in the cycle but it certainly could happen.
Looks like this was what happened to my 3.5g tank before.
 

tuffcookie

Member
I did the test tonight, got the same result I’ve been getting for a week now. Also did dilution test

1st pic with 4 tubes is the regular test
2nd pic with 2 tubes is the dilution test

Came out to be the same colors

Sorry pic and lighting quality is horrible. But in real life, nitrites are >5ppm and nitrates are about 5ppm

 
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mattgirl

Member
tuffcookie said:
I did the test tonight, got the same result I’ve been getting for a week now. Also did dilution test

1st pic with 4 tubes is the regular test
2nd pic with 2 tubes is the dilution test

Came out to be the same colors

Sorry pic and lighting quality is horrible. But in real life, nitrites are >5ppm and nitrates are about 5ppm

The dilution test is telling us that your nitrites need to come down and that can only be accomplished with water changes. Seeing that deep purple in a dilution of 1 part tank water and 4 parts source water tells us that even an 80% water change won't be enough.

Do you have any idea as to exactly how much ammonia this tank has processed? You said you add enough to get it up to 4ppm and it drops down to 1 or 2. Does it ever go down close to one or do you dose it back up to 4 each time it drops back to 1 or 2?

BTW: What size is this tank? What temp are you keeping the tank at?
 

tuffcookie

Member
mattgirl said:
The dilution test is telling us that your nitrites need to come down and that can only be accomplished with water changes. Seeing that deep purple in a dilution of 1 part tank water and 4 parts source water tells us that even an 80% water change won't be enough.

Do you have any idea as to exactly how much ammonia this tank has processed? You said you add enough to get it up to 4ppm and it drops down to 1 or 2. Does it ever go down close to one or do you dose it back up to 4 each time it drops back to 1 or 2?

BTW: What size is this tank? What temp are you keeping the tank at?
40gallon. I think I messed it up. I had thought I was supposed to dose to 3 to 5 ppm every time I see it fall down below 3. I read somewhere else that I’m supposed to wait for initial dose to get to 0 before redosing. Head desk moment, this is my first time doing fishless cycle

Every time I redosed it went back down to 1 to 2 ppm the next day

I’ve redosed 3 times total since 11/21 or so I’ll have to check my excel document when I get home. It’s hot in Texas, my other tanks stay at ~80 to 82, without any help from heater so I didn’t bother to put a heater on. But I do have 1 I could use.

Lights also off this entire time except for picture time and I think I have black algae too. The struggle is real
 
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mattgirl

Member
tuffcookie said:
40gallon. I think I messed it up. I had thought I was supposed to dose to 3 to 5 ppm every time I see it fall down below 3. I read somewhere else that I’m supposed to wait for initial dose to get to 0 before redosing. Head desk moment, this is my first time doing fishless cycle

Every time I redosed it went back down to 1 to 2 ppm the next day

I’ve redosed 3 times total since 11/21 or so I’ll have to check my excel document when I get home. It’s hot in Texas, my other tanks stay at ~80 to 82, without any help from heater so I didn’t bother to put a heater on. But I do have 1 I could use.

Lights also off this entire time except for picture time and I think I have black algae too. The struggle is real
You really didn't mess up. One of the good things about fishless cycling is things like this won't harm fish

Temp is fine if it stays up that high without a heater. I also noticed from your previous photos that your PH is good so conditions are good for a successful cycle.

Have you run all the tests on your source water? It is always a good idea to have baseline numbers on the water you are using for water changes.

For now the one thing I would recommend you do is get those nitrites down to no more than 2 even if it takes several water changes to accomplish it. Be sure to condition and temp match the water you are putting back in there. Once you do that add enough ammonia to get it up to 2ppm. Don't add any more until it drops down to .25 or less.
 

tuffcookie

Member
mattgirl said:
You really didn't mess up. One of the good things about fishless cycling is things like this won't harm fish

Temp is fine if it stays up that high without a heater. I also noticed from your previous photos that your PH is good so conditions are good for a successful cycle.

Have you run all the tests on your source water? It is always a good idea to have baseline numbers on the water you are using for water changes.

For now the one thing I would recommend you do is get those nitrites down to no more than 2 even if it takes several water changes to accomplish it. Be sure to condition and temp match the water you are putting back in there. Once you do that add enough ammonia to get it up to 2ppm. Don't add any more until it drops down to .25 or less.
I did >80% wc last night, here’s what I’m getting today. The ammonia has dropped significantly but nitrite still off the charts. WC again today? The seachem ammonia indicator was at green 3hrs after WC but yellow this morning.

I also swapped out the canister filter unit last night, not sure if that made any impact. I put all the sponges, etc into the new one but the activated carbon because the bag didn’t fit in the new unit


 
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mattgirl

Member
Looks like your nitrites were super high since they are still this high after the water change but of course we already knew that. We know that your cycle is moving forward because the ammonia went down. I would just go ahead and add ammonia again and see where you are tomorrow. It is possible the water change will have got things moving forward better and if that is the case these nitrites should start going down on their own within a few days.

If they don't within 3 or 4 days another big water change may need to be done.
 

Virgo

Member
Yes I think you’re good too. At least your ammonia eating guys are working. Mine just got stuck at where it was until I made water changes. Not sure why really.
 

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