okay ive been setting up a 120 gal. tank for predator fish. I had my tank cycling for 2 weeks then i put in bio-spira from instant ocean, waited a week and i put a big puffer in there. i was so worried it was gonna sell and i wanted him so bad. anyway my nitrite lvls r high because its still in cycle. so my question is. is it okay to do a 30 gal water change like every few days to keep all lvls lower? or do i need to take other action all together