I've run into many cycle-stall problems.
Nobody's asked whether you used softened/RO/distilled water.
Everybody reads books and pages and articles about what to do to keep the fish alive but I've only found one page that talks about bacteria.
So, some tidbits about bacteria.
Nitrification bacteria need high-ish pH to grow and thrive.
Nitrification bacteria consume water.
All bacteria need calcium.
All bacteria have to do chemistry to poop.
No bacteria like light.
No bacteria like Chloramine, it looks like ammonia but kills bacteria who eat it.
There's no guarantee that the ammonia in a bottle is free of other contaminants so what I do is toss in old food and stir it down in.
Also get a couple boxes of cheap distilled drinking water jugs down at the store, this is to keep from having to add prime/aquasafe during cycle-up.
Add untreated water to new tank, add filter with all parts, run without carbon or heat for a half day.
Add prime at ONLY two drops per gallon other chlorine/chloramine additive at minimum dose gallon. Continue running for about another five hours.
Stick in carbon filter and run for about five more hours then remove carbon.
I add one cup of bottom rock in a filter's bag from another aquarium down where the output flow circulates at this point. If you're going to use the same rock you can just dump it in but make sure it is all together to hide it from light.
Now adjust your pH a little, DON'T use liquid acid use low pH buffers like discus buffer. The point here is to add not only the pH lowering buffer but also to add a raising buffer in order to put a high load of calcium in the tank while keeping the pH over 7.5.
Throw in stale fish food, anything will do... you can even pour it into the back of the filter so it lodges in the bio-media if you like. I usually have some dregs of Fancy Guppy around, it's over 50% proteins.
Turn on the heater, no warmer than the range your tank will OPERATE at. There's no point in having bacteria that like ninety five degrees in a seventy four degree tank. They do mutate and genetically adjust.
Walk away for a few days and expect to lose a fair bit of water.
When you come back to check the tank for cycle there are some things to watch for:
High ammonia content can stop the bacteria from reproducing, seems odd but ammonia is also toxic to the bacteria that eat it.
Nitrite climb over the top of the scale is very very bad it can cause substrate saturation. Nitrite is the carbon-monoxide of aquariums.
Nitrate over 130 can start slowing reproduction of bacteria.
If your ammonia is over 4, nitrite over 5 or nitrate over 150, do a water change with the distilled water. I've actually stalled a starting cycle using treated tap water. You can use carbon filtered or RO water instead.
Hardness is kinda like the mineral and salt solution in ocean water. Evaporation should be replaced by purified water but any water removed from the tank should be replaced with your normal replacement water.
I have actually stalled biology in a tank both from too much hardness and from not enough.
So you've got to have hardness, high normal pH, control of ammonia nitrite and nitrate, darkness and truly clean water.
Break down that stalled 5 gallon and do a sink water rinse of everything on its filter except the bio-media and bung the filter on the other tank with the media in it. Drain the stalled one out and fill it with all but a gallon then stir in two drops per gallon of prime and throw in an air stone on "blend" output. Give that a day then add in one gallon water from a live tank and put the filter back on it with about six days worth of fish food in the back.
And, my best advice. Start your filters a month before you set up a new tank, run em in a tank you already have control of. Remember that it takes a bio-wheel about 30 hours to completely wet and become calcified media for bacteria.
I usually cheat at cycling a tank, but being a filter tinkerer I have lots of sleeping filters around.
Last edited by Thunderloon; 02-10-2011 at 10:05 PM.
Reason: dosage comment correction