Any nitrates yet? If you're still adding ammonia everyday and the nitrites are staying at 5ppm then that means some of it IS being converted, just not enough.
Nitrates are right around 5.00ppm and have been there for about a week now. I have been adding small amounts of ammonia every morning just to keep the bacteria alive.
UPDATE: alright so I did another 20% water change yesterday. Retested my water an hour later and ammonia was 0. Nitrites were still 5.0+ppm and Nitrates were zero. (down from 5.00ppm where they have been at for a week). This morning I checked my Nitrates again and they were still zero. 5 hours later I checked again and this is what I got! Whoaaaaaaa! This makes me very very very very happy! Yes, nitrates are still high but at least I know they will disappear soon!
It might not have stalled though it's entirely possible with the levels that high. I would do a 50% water change at this point to get the nitrites between 2-4 ppm and let the rest take care of itself. Your almost there bro lol
Update: 24 days since my tank has been filled. I won't say much right now, im gonna be late for work but here's a pic for you guys..... . Words can't describe how happy I am! Big thanks to you guys for supporting me and telling me to stay patient. It finally paid off. So now I can officially say, as my title goes, My 75G is FINALLY done!!!
the piranhas are a hardy fish, they ll addapt to what ever water you put them in. when I had my piranhas i put them in the tank the next day after the tank was set up. and Ive never tested the water. just do your weekly water change and cleaning and youll be fine. good luck