i have the same problem now
郎頭 was good, but now ......
I change water 2 times a week. each time I change 1/8 amount of water. Still no good.
If I put Hammer in dark place, it opens a little.
No2 and No3 has no problem. Temputer is around 26. Ph 8.3
I really have no idea what is happening to my tank