I was doing some research and reading old posts, nosin around etc and found that my low Ph may be caused by the high ammonium level. So while the ammonium is good at detoxifying the evil ammonia its dropping the Ph. The fish seem fine with a really low Ph ( and don't seem to care about the ammonium levels...although the corys have been odd..) whilst all that seems good and safe and keeping the fish alive, the cycle has stalled- no bacteria to eat the ammonia- or not enough. I will never get accurate ammoniA levels due to the prime dosing- I know it wasn't zero. Nitrates are low but good- between 7 and 10. nitrites are zero. SO since we don't use tap water when we do the water changes and what we get is close to 6 and the tap is 7.5, we did a 30% water change ( 20g) and hopefully that will bring the Ph closer to where it should be, get the bacteria right for eating the evil ammonia and not shock my fishies. Also changed out the carbon filters as they were disgusting. when I checked the Ph after the change it was between 6.6 and 6.8-- I will check it again in a few hours once everything has run thru the filter, had a chance to mix etc and see where we are. clear as mud?