Nitrites

[thommo75]

Guys,
Having dramas with nitrites in my tank.

Info about my tank:
340L tank
Fine sand substrate less than inch thick
Eheim 2217 canister filter
CO2 system with solanoid PH controller
Air stones

Water Parameters
GH 8
KH 4
PH 7
TDS 200
Ammonia 0
Nitrates 0
Nitrites 0.25-1 (dependent on WC)

Fish:
2 x medium discus
10 x tummy nose
5x cardinal tetras
5 x juvi peppermint bristlenose

Feeding twice a day with beef heart and once a day with pellets. Food is usually eaten within 5 minutes.

Tank has been running for about 2 months, within last month I added 2 x medium size discus, 5 rummy nose and 5 juvi peppermint bristlenose. Tank was fully cycled before these fish were added.

2-3 times a week I do 60% water changed. Water is aged and all parameters are same as tank.

Did I add too many fish at once or is there something else I'm missing.

Thanks.

[FishFanMan]

Sounds like you have inadequate biofilter capacity. You put in too many fish at once and you may not be cleaning the fish poop enough because you seem to have a heavy planted tank with that injector. I would remove the plecos for awhile, vacuum in between the plants and to multiple 50% WCs to bring the nitrite to almost zero. And let the good bacteria catch up to the additional bio load. Or put the new discus into a 20L and do daily WC in that tank and let the main tank catch up while feeding minimally in the main tank. Big WC in a 20 is so much easier than the big tank.

[Kyla]

Or put the new discus into a 20L and do daily WC in that tank and let the main tank catch up while feeding minimally in the main tank. Big WC in a 20 is so much easier than the big tank.

i would just add that while removing the discus to another tank will prob help the nitrite issue in ur main tank, the BB in the main tank will only grow to match the food source (ammonia) and without those discus present you may still experience a mini cycle when u add the discus back in because there wont be enough BB present to handle their bioload.

u could grow BB on a sponge filter in the smaller tank holding the discus, and then transfer the filter and all its BB to the main tank with the discus. but keep in mind that it will take a while for the BB to become established in the filter media of the small tank, esp if you are doing huge daily wc...

so either way u r looking at more wc to bring nitrite to 0

[MD.David]

Here again is someone that doesnt have enough nitrification for their bioload.
•Loose the substrate
•Change water 80% daily
•Get a large sponge filter (ATI #5 hydro sponge or XY380 Chinese sponge filter) and add it to your tank.
•why do you only have two discus?

[DJW]

i would just add that while removing the discus to another tank will prob help the nitrite issue in ur main tank, the BB in the main tank will only grow to match the food source (ammonia) and without those discus present you may still experience a mini cycle when u add the discus back in because there wont be enough BB present to handle their bioload.

u could grow BB on a sponge filter in the smaller tank holding the discus, and then transfer the filter and all its BB to the main tank with the discus. but keep in mind that it will take a while for the BB to become established in the filter media of the small tank, esp if you are doing huge daily wc...

so either way u r looking at more wc to bring nitrite to 0

This is a sensible approach and will make things easier, however if you think ahead a little there is the question what to do with the sponge filter when it goes back into the main tank along with the discus. The sponge will be carrying 2 discus worth of beneficial bacteria, so if you wanted to remove it from the main tank you would have about the same mini-cycle you started with.

Two discus isn't a lot, so this is more of a thought experiment. If you don't want the sponge filter in the main display tank, one thing you could do is chop it up and add the pieces to the canister filter, but you would have to make room for it.

I have another suggestion for handling a mini-cycle like this. Adding 1 teaspoon of salt to the 340 liter tank will eliminate 88% of the toxicity from 1 ppm of nitrite. Adding 1 tablespoon of salt to the 340 liter tank will eliminate 96% of the nitrite toxicity. If the nitrite level goes down or up you can adjust accordingly. This small amount of salt shouldn't be too hard on the plants.

With the salt method, continue a good water change regimen, and monitor for both ammonia and nitrite. When doing water changes, add a portion of the salt dose to the new water. After the tank is fully cycled, stop adding salt.

Note: salt only blocks nitrite toxicity.

[thommo75]

Thanks for the advise guys, however before I had a chance to implement any of the suggestions the nitrite dropped to zero. Not sure if it was the poly filter I placed in the canister filter, removal of prefilter on intake of canister to increase water turnover or just the good bacteria catching up with the bio load. Thanks again.

[chuckiesmalls]

phew! Is this true about salt? 1 teaspoon eliminating 96% of nitrites. I've heard its effective but had no idea it was THAT effective! I hope so...

Got 7 new fish recently in a new 65 gallon (seeded filter on a well-established tank) and while I have gotten my ammonia mostly under control I noticed I had a nitrite spike this morning before work and added some salt after a small water change I was able to squeeze in.