I would keep your PH at 7.2 with muratic Acid. The lower PH may help the crystals dissolve. Brush constantly as much as possible while the pool is at shock level. A couple things....
PH will read false high when you are shocking your pool, which is sounds like you need to do. So, first lower the PH down to 7.2. Wait an hour, and shock the pool based on the CYA level in your pool - refer to the CYA chart. You will need to test and add bleach frequently to maintain shock level. While the FC is above 10, the PH will read a false-high - ignore it, and only adjust the PH down to 7.2 IF THE FC IS BELOW 10. This is important, because if you try to adjust the ph while at shock level you could end up with pH that is too low, okay?
After your FC has held overnight (perform an
overnight FC test to determine this) if you maintain a low PH level of 7.0-7.2 for awhile, while brushing, hopefully you can remove the crystals.... I assume this is a plaster pool, since you are using a metal brush?
If this is plaster, after this is taken care of and your levels are stable, you'll need to raise your CH it's too low for plaster. IF this isn't plaster, you shouldn't be using a metal brush on vinyl.
It would help us if you put your pool specs/info in your signature. Go to User Control Panel, then Profile, then Edit Signature.