I'm just wondering if anyone has seen a similar issue. Could the ph cause misleading results on other tests? I'm cycling an 80 gallon tank, and it seemed to me like things were almost done. My nitrites were down to 0.25, and my nitrates were climbing. Ammonia went from 2 to 0 in a day. Then it all stopped. Ammonia stopped being converted. I read somewhere in a forum after googling that the nitrates could get too high and it could stall the cycle. I did a partial water change, dosed ammonia to 2, and after a day the ammonia was gone again. Nitrites still at 0.25. A few more days went by with nitrites at 0.25, and everything stopped again. I then googled again, and read that the nitrates weren't to blame but it could be the ph. I measured the ph. The tetra test goes down to 5, and it showed 5. So it could have been even lower. I made an 80% water change and got the ph up to 7 (the tap water is 8). But after the water change (I tested immediately) my nitrites were way up. Now we're talking 1-2. The tap water has 0. I can't see how the nitrites can go up after a water change. Could it be that the test kit couldn't handle the ph? I dosed ammonia to 2, and this time it took 2 days before it went down, so I guess I hurt the cycle a bit by making the big water change (or maybe it was caused by the ph problem), but it's moving again at least. The nitrites haven't decreased however. And there's algae everywhere. How does that affect the filter? Will the current just flush it away? I've cut the lights to 4 hours now. There's some of the algae which is denser and has a slightly different color than the rest. I just hope it's not cyano bacteria Could that out-compete the beneficial bacteria?