X2, it is GHA, but in order to tell you how to get rid of it, we need to know a few things:
1: Params. Po4, calcium, mag, alk.
2: water source. I need the TDS of the water container and directly from the output source.
3: how old is the system?
4: what rock did you use?
5: what sand did you use?
6: what's the current stock list?
7: how much are you feeding?
8: what kind of equipment are you using?
Answer those and we can tell you what's up.