cycle wont complete

[basketcase]

ive been cycling a new tank for at least 5 weeks now. for over a fortnight a high reading of nitrite has been present. nitrates are there but never seem to spike only reaching 10ppm.

i havent done any water changes at all, ive got a dozen tetras in the tank ( a few have died off due to the nitrite) and the temp is a constant 30.

any suggestions as to what could be stalling the nitrite to nitrate conversion?

[Hollowman]

Might be a bit hot, maybe lower it to 25C Also, what is your ph? I believe cycles are better at a ph>7

[ILLUSN]

give it more time it will stabilize if you can get a litle media from someones elses 30C tank it will go faster

[basketcase]

days later still no change. so roughly 7 weeks now this tank has been cycling. and at least 5 weeks waiting for nitrite levels to drop.

im almost convinced the nitrite reading is false, its been way too high for too long without any tetra deaths to be an accurate reading... what could cause a false nitrite reading? Big L?

[Hollowman]

Try a new test kit :?

[DiscusJoe]

As said above, check your ph. If it has crashed, it will delay the conversion. Keep it around 7-7.4 What are your ammonia levels? You also have small fish in there which doesn't create a huge bio load, though you haven't said how big your tank is. Are you intending to add discus?

[ILLUSN]

There are many types of bacteria that work in the nitrogen cycle, diffrent strains perform better at diffrent temps and ph. To cycle a tank propperly set it up to your final conditions in my case thats always a temp of 30C and a ph 5.5-6.0, my cycle typically takes 2-3 months from a bare clean tank.

If you can add some media from a system similar to yours (like another filter in the fish room) the cycle will only take days (my personal best is 48hrs).

If you cycle a tank at low temp with a high(er) ph then drop the ph and raise the temp theres a good chance you'll kill of the bacteria in the filter (diffrent strains work better at diffrent temps and ph's) and have to re cycle anyway.

Replace your test kit, test your source water and let it run its corse.

[xferno]

take a sample of water to your local fish shop, they should do free tests and you can compare the results to yours

[Greggy]

It is my experience that a bare tank can take even longer than 3 months to fully cycle, and even then it takes more time to fully settle down to what I would call 'stable'.

Thinking back I don't think my virgin 6x2x2 was properly settled for approx 6 months.

Cheers

Greggy

[Old Dave]

If you can add some media from a system similar to yours (like another filter in the fish room) the cycle will only take days (my personal best is 48hrs).

I just experienced a 4' in which the nitrite wouldn't settle down.
Added a large old working sponge filter and it went to nitrate=0 overnight.
I'll leave it there for a week or so, just to make sure.
When it comes out I'll monitor the water/filter for a while just to ensure the new filter can handle the load, but I am expecting only to prove Jothy is 100% on the money...again :salute

If it is a brand new tank, it will always take longer.
Must be something to do with the glass surface itself.

hth,
Old Dave