All of my levels within normal ranges except for ammonia, PH 8.2, Alk within normal range, Nitite and Nitate ( one of them is 0, the other is less than .10), ammonia is .25, what should I do to get this down. Tank has been cycling for 3 weeks now and my Power Heads are on the top rim of the tank, where the jet streams cross over top of the LR. (55 gal with wet/dry with bio balls/sump, 2 402 pow. heads, 55 lbs LR, 60 lbs LS, berlin skimmer). Should I move the pheads down inside the tank or does it matter? , when can I start to add some inverts?