Hi! I need your help. I am at my wits´ end. The problem is that my new tank of 15 litres has been cycling for 2 months already. I was even forced to change my old (it wasn´t actually old) filter for a new one, as it didn´t produce oxygen anymore. Now that I have the new filter in the tank, it naturally takes time to go another period of cycling through again (p.s. I took the old one out after I had installed the new one).
Does anyone have an idea, where did I go wrong? I have done small water changes every day, but I have never cleaned the gravel (it doesn´t seem (that) dirty, anyway).
p.s. I have only 1 big goldfish and few plastic plants in the tank.

What do you mean by your old filter not producing oxygen anymore? What kind of filtration is currently on your tank and what are the levels of ammonia and nitrite hovering around? My 20 gallon took about a month-and-a-half to cycle.

Sorry, Melle, for confusion. I meant aeration by that. My old filter (Crystal Duo R10) didn´t aerate porperly anymore.

Anyway, it seems that once I complain about sth, it sorts itself out at once. I mean, I went home after I had complained here, and guess what, the water in the tank was clear!
I don´t except it to last long, though....but I´ll keep a close eye on it.

Thank you, Melle for your help!

month and a half to cycle a 20 gallon??? with fish???

Merca, are you also cycling with fish?

Yes, 20 gallon with 2 moors. Is 1.5 months that long or short? I kept ammonia below 0.5 ppm the whole time and nitrites below 1 ppm...the fish came through fine :-)

When I get a bigger tank I will probably buy the BioSpira that everyone promotes for fast cycling, but by then I'll be making more $.

Merca--glad things sorted themselves out. As you said, keeping an eye on things would be best for now. Once biological systems reach equilibrium they can absorb minor changes without effect, so if your tank stays stable for the next few weeks you are probably in the clear

Hi, purple! Well, I think the reason why it cycled for so long is that the water temperature in the tank was relatively low - around +20C all the time. I hear that the high temperature quickens the cycling process, but I had to keep the temperature low, coz the smell was simple unbearable. Fish was fine, however (I did keep it in the tank all that time).

Hi, Melle! Glad to hear that! The water in the tank has been clear for 5 days now. I hope that it will stay that way

oops! sorry, purple, I thought you were talking with me!

Merca--I kept my tank at room temp too (didn't want to bother with the heater). I never noticed a smell, but we live with an indoor cat/litterbox so maybe I'm not very sensitive