Do you have your complete water test results please? Ammonia, Nitrite and Nitrate being most important.
If you are cycling with fish, your aim is to keep the ammonia and nitrite 0.25ppm or below for the health of the fish.
Ammo Lock is known to give false ammonia readings, so i would stop using it and perform daily 50% water changes, as many as required until the levels are safe for the fish. Test your water after an hour or so of doing a water change, if the levels are still not 0.25ppm or below, then it is safe to do another 50% water change. Try to keep the water going back into the tank roughly the same temp as the water in the tank so as not to stress the fish.
The ph could be a false reading, or be effected by the ammo lock or could have crashed due to the cycling, the water changes will bring it back up to normal.
Edit to add; On the first water change, you may want to slowly add the water back in, if you have had a ph drop, then the fish need to acclimatised back up to the normal ph range or you could shock them. Trickle the water going back in over the course of an hour to slowly raise it back up. After that if another water change is needed, you can be a little quicker with the re-fill.