Cycled tank added fish now nitrites :(

[p@ul]

Hi guys my tank finished the cycle over a week ago
I added 5 glowlight tetras last weekend and now my readings are
Ammonia 0
nitrates 10
But i now have nitrites at between 0.1 and 0.4
This is after a 90% waterchange ive just done (really confused now) :(

please advise

[Rbishop]

Another water change to get nitrites to a zero reading.

Liquid test kits or strips?

[p@ul]

Ive got both but i only use the liquid :)
Just done another 90% water change and its dropped but still on 0.1
Its also took nitrates down to between 5 and 10

[got2envy]

90% water change might be to much..50% at a time is good enough i think...90% is stalling the cycle..there has to be some nitrite to get the nitrates going..nitrates will not kill your fish...eventually they will go away with 25% water changes every week..do the fish look stressed or looking or acting weird? remeber when you are cycling a tank the nitrites are going to spike up..then you will get the nitrate reading and then everything should read 0ppm

[p@ul]

I thought any type of water change was good,the more the better?
Also i read on here you cant stall the cycle as water changes do get the beneficial bacteria out of substrate ornaments etc :(
Also the tank had finished cycling thats why i added the fish,could it just be a mini cycle?I still have nitrate readings of between 5 and 10 and ammonia is still 0 its just nitrites thats risen slightly :)

[Deddo]

How long did you cycle the tank before putting your fish in? Do you have any plants in it?

[Rbishop]

You are doing fine p@ul. The water changes will not stall anything. Just continue with them as your nitrite testing requires. The time span between changes will increase, ammonia and nitrites will be zero and nitrates will climb.

Add new fish slowly, a few at a time and let the bacteria catch up.

[Blueiz]

I thought any type of water change was good,the more the better?
Also i read on here you cant stall the cycle as water changes do get the beneficial bacteria out of substrate ornaments etc :(
Also the tank had finished cycling thats why i added the fish,could it just be a mini cycle?I still have nitrate readings of between 5 and 10 and ammonia is still 0 its just nitrites thats risen slightly :)


I bet you had an ammonia spike before you had a nitrite spike..;). This is not an uncommon occurence, especially in smaller tanks. You didnt say what size your tank is, but Im going to throw out a guess that it is a ten g. Keep an eye on your parameters, do water changes as necessary to keep your nitrites as low as possible. When adding fish, regardless how long the tank has been established, you will have a spike in parameteres. This is because you have increased the tanks bioload and the bacteria have to catch up. Most of the time this spike goes unnoticed. Seems to me as if your bio-filter wasnt established enough for the parameter spike to go unnoticed, but it is recovering quickly.

Water changes do not stall the cycle. Until your biofilter is established and able to consume the ammonia and nitrites, you will have these present at all times in the water no matter what you do. In your case it is the nitrites. Bacteria only grow at a certain rate, no matter how much waste is present, the bacteria arent going to grow any faster. I like to use this comparison when talking about this, kinda makes it easier for others to understand. If you come home from work-school and it is cold in your house. You turn the heat on. No matter if you set the thermostat on 75 degrees or 100 degrees, the house is only going to warm up so fast. Doesnt matter what the end temperature you want it to be in the house. Same goes for bacteria.

Blue

[p@ul]

Excellent explanation m8 thanks,i think basically what i have done is add too many fish at once maybe?although i was cycled i got 5 glowlight tetras at once as i read this really is a minimum amount they like to shoal in :) i aint to worried about it as a water change only takes me minutes and ive been doing one every day/2 days religeously

[Blueiz]

Excellent explanation m8 thanks,i think basically what i have done is add too many fish at once maybe?although i was cycled i got 5 glowlight tetras at once as i read this really is a minimum amount they like to shoal in :) i aint to worried about it as a water change only takes me minutes and ive been doing one every day/2 days religeously


Yeah, added a few to many at once, good thing is.. you already have all the bacteria needed, so in a few days to a week you should be fully cycled again.

Blue

[p@ul]

Never understand that,you go in a lfs and they say 1 danio for £2:50 or 6 for a tenner saying on the front they like to shoal in 6 etc but you buy the 6 and then its too many fish at once lol