Flakes coming out of UV

[dwest]

Those are very likely calcium carbonate deposits that form on the bulb then flake off. You can decrease those by increasing the flow.

 

[RaisingTinyHobbits]

I think I would put some of those flakes in acid to see if they dissolve, or not. Scale should (?) dissolve? @Randy Holmes-Farley

Good idea. I’d like to see what happens when added to vinegar or citric acid.

Do the pieces fizz?

I sprayed a piece with some white vinegar I had in a spray bottle and there was a tiny bit of fizz on firat contact, but not a lot. Once I get a chance to grab some gloves I'm going to try some citric acid and see what happens.