High nitrites in cycle of 75g
 

I have been cycling my 75g for a couple of weeks now. I am able to convert ammonia with in 24 hours to nitrites and I do have nitrates but my nitrites are off the chart no matter what I do. A couple of days ago I did a 1/2 water change and today I did a 3/4 water change. RIGHT AFTER the water change a test for nitrites still shows deep purple. I tested my tap water and water in another tank (just to be sure) and both test 0 for nitrites.

If the tank was sitting for some time and had nitrites I wouldn't mind but for it to be deep purple right after water change? That cant be normal.

I am using PFS for substrate. I have a tufa rock, a piece of texas holey, and some basic aquarium rock (cant remember name) from a LFS that specializes in cichlids.

Should I be concerned? Should I just keep feeding the tank ammonia and hope one day soon the nitrites removed on their own?

Nitrates remove the Nitrites, and by feeding Ammonia your getting it to build Trites, but Trates build in time. That is why you are haveing a hard time with those, they haven't grown enough to put a dent inthe Trites as of yet. you have to give it time, they will come down, thats nature. It will happen. Quit dosing anything, the cycle has started, most mess it up and its takes longer because of messing with it.

Two weeks to see ammonia drop that quick is actually pretty good. You can expect the nitrite eating bacteria to take nearly as long to catch up to the ammonia eating bacteria. That's in my experience anyways.

If I quit dosing the ammonia wouldn't the bacteria that start the first stage of the cycle die?

Nope, its in the tank already, and thats the idea of a cycle, to grow the bacteria that eats one another, then the actual bacteria helpers that are beneficial are left. When the Trates are the only thing left and under 40, your all clear. As long as you don't just leave the tank sit, you add fish, thats adding the constant ammonia to feed the bacteria.

I may not have been correct in doing so...but I was kinda thinking along the same lines as you Bizness...so I dosed a small amount of ammonia once a week just to give the ammonia bacteria something to eat. It took my tank about 5-6 weeks to cycle so I don't think it hurt anything.

As a final test before I added fish, I dosed up to 5ppm ammonia and made sure that it and nitrites hit zero in 24 hours or less. When it did I knew I was done. I did a huge water change to clear out some nitrates and went and got fish.

Yes, it can be done with no issues. You say dosed a small amount. Some keep dosing, thats how it gets messed up.

The nitrites are gone!!!!!! :-D

I tested the water yesterday and it was still deep purple. Today it now shows 0. I just dosed it back up with ammonia to make sure but I see a trip to my LFS on Friday.

Why on earth would you do it again?

my understanding is that one last dose can verify that the cycle is up and running, if ammonia and nitrites are back down to 0 in a day, you're good to add fish.