Metal stains at the same locations

[Ke]

I get metal stains at the same spots in my fiberglass pool every few weeks. When I apply ascorbic acid, the stains disappear completely and the surface looks perfectly white again but when I run my hand over the area I can feel some roughness. What happened was the pool was put in last fall, winter/snow came before electrical was hooked up, the pool was filled with water, there were lots of leaves and dirts in it. The PB covered the pool with a large tarp. In the spring the PB was able to get the swamp back to crystal clear without changing the water. Before the tarp was put on I remember I used my hand to wipe away some stains(didn't know what kind of stain that was at that time) at one area on the pool wall, so now the area that I wiped stays stain free but right next to it the metal stains always start to form because of the roughness, I tried scrubing with a brush but didn't help. Other than this minor issue my pool is stunning with sparkling water.

 

[frustratedpoolmom]

If you could post a full set of test results we could better advise you. Metal sequesterants are helpful at preventing stains from returning, as are maintaining your CH and PH levels in a recommended range for fiberglass.

Welcome

 

[JasonLion]

I suggest adding some sequestrant.

There will always be some spot that stains first. If it wasn't there it would be somewhere else. If the roughness doesn't bother you otherwise I wouldn't worry about that spot.

 

[Ke]

Here are the numbers for my fiberglass pool:

Salt level: 3200
FC: 2
TA: 100
TH: 250
PH: 7.7
CYA: 60

We have an automatic pool cover, most of the time the cover is closed, we use the pool about 4 times a week, 3-4 hours each, the chlorinator is set at 20%.