white residue or scale in fiberglass pool

[Poolhouse]

Thanks to using the BBB method and advice on this forum I was able to maintain clear sparkling water all swim season with 0 combined chlorine . However, I have had one nagging issue that I could not resolve. My dark colored fiberglass pool developed a scale or residue below the water line over its entire surface. It is hard to see when the walls are wet but when the water line lowers and the walls dry, it is very obvious. The wall is slightly rough below the water surface compared to the wall above the water surface. I kept the water throughout the season as follows:
FC 5-9
CC 0
pH 7.4-7.8
TA 80-120
CH 200-240
CYA 60
salt 3200
I've used nothing but plain unscented household bleach when I've needed to shock (spring and after two parties) and muriatic acid to maintain pH and correct alkalinity (with aeration). I fill from a well that has been tested and shows 0 iron and copper but use a filter anyway just to be safe.
I brush and vacuum at least three times a week. I've tried washing the problem area with baking soda paste and CLR solution but the scale doesn't budge.
Any thoughts?

[CarlD]

Is it actually a deposit or is is possibly damage to the finish layer of the FG?

[Poolhouse]

It feels slightly gritty but I cannot remove it manually or chemically. I worked diligently keeping my water balanced as you can see from my test results. I suspect this is damage to my fiberglass. When it is wet it looks okay but if it dries ( like when the water level drops) the walls develop a white haze over them. Really irks me as the pool is brand new! The fiberglass base color is black with cobalt blue and silver metallic flecks. Stunning, looks like deep ocean water. I fear over time it will appear less sparkly and less "oceany"and more like a black puddle. Oh well.

[karrde97]

I just noticed the same problem for my above ground pool. The water looks lime green yet everything tests perfect. When I stuck my hand in and rubbed the side, it was very course and whitish. I ran a scrub brush over it and it barely made an impact. What is it and how do I fix it?

[kelemvor]

You'd probably be better served by starting a new thread and including a full set of test results in your post as poolhouse did above. Photos can be helpful as well when you're talking about mean green.