Confused About Cycling--Am I re-cycling? Why?

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Aquarium Advice Newbie
Aug 12, 2004
Louisville, KY
After a long almost 8 weeks, my 10 gal. tank finally cycled. In the process, I lost several fish. My water parameters after cycling were 0 ammonia; 0 nitrites; 20 nitrates;
PH 7.2.
I added three guppies one day after the cycling was completed. The tank contained only 2 platies.
Two weeks later, back to cycling again and the loss of two more fish. My ammonia has just gone down to 0 after being up to 5.0. Now the nitrites are creeping up.
What did I do wrong? Did I add fish too quickly?
This is getting frustrating.
Oh, and I've been doing daily water changes since the numbers have gone up again. :(
After you added the guppies, in the 2 weeks before you noticed the problem, did you clean your filter or otherwise do any cleaning to the tank?
Tank Girl,
In that 2 week period I did another 25% water change and cleaned the filter by riinsing it in the removed tank water.
(I didn't clean it with fresh water.) I vacuumed the gravel and that's about it.
Since your load is not really enough to cause a mini-cycle, the only way I see this happening, and I don't know if this is the true culprit , would be that the bacteria was disrupted by the gravel vac'ing, and perhaps if there was a lot of debris in the bottom that got stirred up it could have caused this spike. In the early stages the bacteria will be somewhat easy to disrupt.

Again, I don't know if this is what happened, but the only thing to be done is going to be to continue what you are doing, which is water changes, and the addition of about a tablespoon of aquarium salt and lowering the water level to create splashing or a bubble wand for aeration, which is going to help the fish with nitrite poisoning.

Good luck, and sorry for the setback!
Thanks, Tank Girl. If vacuuming the gravel disturbs the good bacteria and what caused it to re-cycle, should I just do the water changes now without vacuuming. How would I get rid of the debris without vacuuming the gravel?
This hobby is more complicated hat I thought it would be but I'm not giving up yet.
Yep, I hear ya! The science gets mixed up with the art of the thing.

What you can do for now is cut back on feeding so there is not anything sitting there except the fish waste. When you do want to suction up the gunk just hold the syphon tube close to the gravel and let it suck up what it can without actually digging into the substrate, so nothing is disturbed. You might want to do just a portion of the tank bottom with each water change, so you can concentrate on specific areas without feeling like you have to get it all in one shot.

Hopefully this will resolve itself and you won't have any more losses-
Just wanted to welcome you to the board (since TG explained everything already)

[center:a15c6b20e4] :smilecolros: Welcome to AA, hummingbird114! [/center:a15c6b20e4]
I am wondering what the size of the 2 plattys are. depending on size, the 3 guppys could have come close to doubling the bio load. That could cause a spike.

When I clean the gravel I sink the tube down about half the substrate depth. I only clean between a third to half the bottom per week. Havent had any problems doing it this way. It could be the bio-wheel holds enough bacteria that disturbing the gravel has no effect.
Menagerie. Thanks for the welcome........and a big congratulations to you.
Chasgood. One of the Platys (both are no longer with us) was very large for a your theory may very well be the cause of the problem. I'm probably better off sticking with guppies considering the size of the tank. One thing for sure is no more fish for a while. I'll stick with the three guppies I have and hope that they make it through this.
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