Hi vero
vero said:
I added two long fin corys to my new tank two weeks ago. The tank wasn't cycled prior to that. I've been checking the ammonia and nitrite levels since. The amonia went up to only 0.25 and is now back down to 0. The nitrite just went up to 0.25 since yesterday.
What size is the tank and what is the temp of the tank? When cycling a tank with fish is can take as long as two weeks for your ammonia level to fall to zero while you see an increase in nitrite. The amount of time that it takes can vary depending on the amount of species that are used, temperature and the size of the tank. The bacteria will only grow to the fish load that is in the tank, this may be why you aren't seeing a high ammonia level before it dropped off and you saw the nitrite. Just remember that every time you add fish to the tank after the initial cycle that there will be a "mini-cycle" that occurs as the bacteria catches up the increased bioload in the tank. Are these the only two fish in there right now?
vero said:
My understanding was that the ammonia would go continuously up to 6 and then back down? And the nitrite would take much longer before it did anything.
Again, this will depend on the amount of fish added and the species as to how high the ammonia level will be. In a lightly stocked tank there won't be as much ammonia given off as there would be in a tank that is more heavily stocked and two cories don't produce a large amount of waste.
The nitrite to nitrate phase of the cycling process is the longest and can last another 4-6 weeks depending on the factors that I listed earlier. During this phase nitrites can become irritatingly high. The nitrite levels can be kept in check by doing water changes. Gravel vacs will also help and are fine to do. At the worst they will drag the cycle out a little longer but they won't harm the bacteria, the bacteria can't be dislodged by vacuuming. Nitrites are toxic to fish at 2ppm and above, the addition of 1 teaspoon aquarium salt per 20 gallons will help to counteract nitrite toxicity.
vero said:
How long is the cycling supposed to take? A good month and a half? When should the spike occur in that? A month after I add the fish?
On average cycling can take up to six weeks but this isn't a hard and fast time table. The factors that go into determining how long this takes are:
- tank size
- the number, size and type of fish used (some produce more waste than others)
- temperature (the bacteria will grow faster at warmer temps than it will at cooler temps.
Your first ammonia spike occurs when it is readable on the test kit. Each time there is an increase in ammonia or nitrite this is a "spike". After a tank has fully cycled there will be a "spike" in ammonia and/or nitrite when new fish are added. The bacteria needs to grow to the increased fish load. The bacteria will rise and fall as fish are added or lost.
vero said:
Other questions: Do gouramis do good with guppys and tetras? I've got mix information from different books. Some say they shouldn't be put with smaller fish, some say it's fine. Would it depend on which gourami?
This all depends on the species of gourami. Guppies and tetras will be okay with the Dwarf gourami species and the smaller Trichogaster species like the Blue, Gold and Pearl gourami. Of these three the Pearls are the most stunning and the generally the most peaceful. Gourami are also best kept one male to multiple females. The Blue, Gold and Pearls can be sexed by looking at the dorsal fins. The dorsal of the males will flow into a point while the females is shorter and rounded. With the Dwarfs the males are colorful while the females are drab in color.
HTH,
Bryan
