nitrite spike now why?

Question

I have hade this tank for about 4 months and it has already cycled but now for some reason i have a nitrite spike of 0.25ppm i add one fish about a week ago. i have a 55g tank with 7 cichlids i do weekly water changes of 20%. if its because i added one fish how long will it take for it to come back to normal and how do i add more fish with out this happing again?

the tank has already cycled, the ammona went up with the nitrite then nitrate, after that the ammona went away and about a week later the nitrite was gone to and the nitrate leved of at about 2.5ppm 3 months later my nitrite has spiked

i did move some ornaments around could that really be it?

Answer 1

Usually adding a fish would be a bigger cause than moving ornaments.

Moving ornaments might, in theory, cause a slight spike, because they have grown coatings of nitrifying bacteria, which are optimized for nitrifying stuff in their original position. Such a change would be most likely if they were cleaned first, moved to a part of the tank with less circulation, or put deeper into the gravel.

However, adding a fish adds another pooping, peeing, eating ammonia source. Bacteria are usually really good at converting ammonia to nitrite, and almost as good at converting nitrite to nitrate, so having a nitrite spike is pretty normal. It'll go down in a while, unless your tank is overstocked.

Another potential cause of nitrite spikes is if you have cleaned the filter too thoroughly. Most of the nitrifying bacteria take up residence somewhere in the filter gravel, or filter tubes.

A too thorough gravel vacuuming, filter cleaning, or decoration changing just before adding a fish is going to cause more noticeable spikes. Do a few small water changes of 5-10% without much vacuuming in the next couple of days if you feel the levels are dangerous.

To reduce the risk of this happening again, you should remember to wash filter media only in dechlorinated water, and do only one pad (or media, or whatever you've got in there) at a time. Tank cleanings can include water changes, wall cleanings, and filter cleanings, but should not include all three at once.

You can also scratch up your filter (not the moving parts, just the parts that the filter media touches) so that the beneficial bacteria will have a larger surface area on that to colonize, and they should then be better able to recover quickly in the event of too severe a cleaning. However, doing this will make it very hard to properly disinfect the equippment if your main tank ever suffers from a disease outbreak.

Answer 2

the nitrite is the middle of your cycle, so I would get a notebook and log your ammonia, nitrite, nitrate, gH,kH, and pH daily. You should see s tred in your ammonia levels or your nitrate levels as your bacteria grow to accomidate your new fish.

Monitor how much you feed. If there is any leftover food, it can fuel the nitrogen cycle. just keep an eye on it and continue your water changes and it should iron itself out in a week or so. As long as you are watching your levels, you should be able to anticipate a big fluctuation and perform water changes as needed. The nitrite spike most likely happened becuase there was too much wast from wither the new fish or a little extra food. Of they are african cichlids, you have pleanty of room and your tank will be adjusted soon. If they are south american, monitor your water often as the bio load on you tank may be strained.

Good Luck and great job. most people don't even know what nitrite is!

Answer 3

If it's just in response to the addition of one fish, it shouldn't take long to come back in balance. What fish did you add? It's strange that one fish's bioload would affect your balance that much, unless it was a large or particularly messy fish like a pleco.

Did you move any ornaments or plants, or stir up the substrate? Sometimes that can release pockets of trapped gases.

If it's the fish, an ounce of Bio-Spira will boost your bacteria colony immediately and is very stable. If it's the trapped gas, probably all you can do is some big water changes until it's good again.

Answer 4

Adding one fish shouldn't cause much of a spike in the nitrites, but could if he is of any significant size. A week later is about the right timing as well. I would assume that is the cause and if so it should only take 3-4 days to recover.

MM