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Old 10-19-2021, 03:48 PM   #1
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fishless cycle crash?

I was well on my way with cycling 29 gallon tank nitrites finally dropped from its spike ammonia was processing down nitrites were 80ppm then ammonia stopped processing all together I was advised to do a 50% water change I did that added prime with water I put back in. now nitrites have not come back at all ammonia is stuck and nitrates are about 40 nothings happening anymore Iím at a loss should I just start over? another water change? no clue at this point iím so far in the cycle and I think itís completely crashed going on 7 weeks. oh and ph has never moved always stays 7.2 give it more time to process ammonia? did I kill all the BB?

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Old 10-19-2021, 07:26 PM   #2
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How long ago has it been since you did your water change and crashed your cycle?

I cant see how doing a water change could crash a cycle unless you forgot to add water conditioner or something else contaminated the tank. But, i have no reason to doubt what you say. So i cant really explain whats happened. Maybe the bacteria was in the water column and hadnt established properly on your filter media?

What alternative do you have apart from get back on the horse and try again? You could do 100% water change and switch to a fish in cycle.

If you want to have another go at a fishless cycle i wouldnt change any water as long as your ammonia is at a good level. At least that way you arent waiting to produce nitrite so your nitrite to nitrate stage can get going. I would probably redose water conditioner to be sure there is no chlorine in there.

What is your ammonia and nitrite at now?

Getting some filter media from and established aquarium will speed up your cycle. Bottled bacteria like Dr Tims One and Only might help. You may have already done these first time around.
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Old 10-19-2021, 08:50 PM   #3
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I’m thinking exactly as you said in the water column I am only cycling with a double sponge filter that sticks on the back of the tank and I do believe that could be slowing things down so I have added a aqua clear 50 hob filter yesterday . I did dose the prime I will redose to make sure how much should I put in i know one cap full is for 50 gallon this is a 29. Ammonia I redosed at 2ppm this is for one axololtl so I don’t think I have to go with the full 4ppm. Nitrite is completely gone when I did the water change nitrite had finally just went down to zero after it’s spike to 5ppm when I did the water change it was 0 ammonia 0 nitrite only nitrates were left. Now i’m just left with 2ppm ammonia and about 40 nitrates it’s weird there’s no nitrite even with it going down to zero before the water change it would still slightly rise with the ammonia being added
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Old 10-20-2021, 02:18 PM   #4
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You haven't mentioned how much filter media (size) and type of filter you were using. The addition of a filter will help, just keep in mind you need to build up BB and it will only grow and thrive in the filter media as long as it is oxygenated (water flowing through it) I would stay away from carbon and such for now, I would use most of the filter's space with sponge type media. Never change the filter media or rinse it especially while cycling, later on, an occasional rinse in tank water will suffice. Another thing I always mention and from my own experience in the past whether fish in or not cycling... patience!
I wish I could be of more help but I've never done a fishless cycle but these are pretty much all same steps.
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Old 10-21-2021, 01:06 AM   #5
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You should be fine cycling with double sponge, should be plenty of material there for bb to establish on, especially for a fish less cycle.

So if I read that right, nothing physically changed with the tank it just suddenly stopped processing ammonia, then at that point you started water changes?

At that point the cycle was already disrupted so the water change likely had no bad effects on it. Seems strange for it to suddenly crash with no outside influence.

Didn’t happen to have a power outage at some point where the tank temperature could have fluctuated drastically or in the case of some “hob” filters, if the water is low enough they’ll syphon back and pull the water out of the filter housing allowing some of the filter media to dry up (not good for the bb).

Didn’t happen to miss dosing ammonia for more than a few days? Depending on the amount of bacteria and the ammonia levels in the tank, if left too long between dosing you essentially starve the bacteria and they’ll start to die. Though I wouldn’t think you’d completely crash it by waiting too long between dosing, I could see it definitely slowing it down. The bacterial cultures only grow as big as they’re fed!
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cycle, fish, fishless, fishless cycle

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