Hi All,

My pool has been covered for about 2 weeks (solar cover) because weather and temp. has not been ideal swimming weather. I have been testing the water every-other-day, though, and keeping up with the water. Today, I rolled off the cover and noticed 5 stains at the bottom. Each stain is round and very large - ranging from 4"-6". 3 are in the shallow end and 2 are in the deep end. I have a 16x33 IG fiberglass pool that was installed this June - 13,500G. Fiberglass is light blue. The stain appears as light brown - it's almost like a grease stain bleeding through! If it's sunny out, you can't really see it, but if it's cloudy, you can see it pretty well if you look for them.

Since installation, I've been using Cl pucks. I'm aware of the CYA issue - but current levels are okay, so I haven't switched yet to bleach. Only during the past 2 weeks, the Ph levels dropped a bit, so I added some pool-store PH+ (bought the Soda Ash before I knew Borax would be ok). Did this about 4 times this past week - adding about 12 oz each time. Right after installation, I did put CYA in. And, I did shock once in early July using cal-hypo. Have not shocked since. Water has been crystal clear and have had no water issues.


A recent test done today:

Cl: 6 (Consistent between 3-6 all summer)
FC: 6 (Never ever test positive for CC)
CYA: 50
Alk: 90 (conistent over the summer)
Ph: 7.3 (since installation, was very stable at 7.5. Since covering 2 weeks ago during non-swim times, pool seems in need of PH+ sometimes.)

I'm probably going to call the fiberglass manufacturer on Monday, but thought I'd post this to see if any fiberglass owners ever experienced this issue. Seems like the fiberglass somehow got stained. And, the only thing differently done in the last 2 weeks was the add of Soda Ash and covering the pool when not in use.


I would have posted a picture, but the camera is not picking up the stain. I am running a heat pump, too and keeping the pool at 86.