Hi All. I recently purchased a new home in Northern Florida with an 11,000 gal SWG in-ground pool. I noticed that while the water was clear, the surface (?) had an overall yellow/tan appearance. Inspecting the finish on the steps where it's shallow, I noticed the owner chose a tan finish vs a white/blue that I'm more accustomed to seeing. Even so, it looks like some areas of the finish is lighter than the rest which makes me think the finish is stained overall.

Attached is a photo. I tried getting close-ups of the lighter areas but the picture didn't capture the contrast of light and dark (no stain was visible from photo).

My initial testing from Pinch a Penny was: PH 7.8, FC 5.0, CC 0, CH 300, TA 115, Stabilizer 60, Salt 3200. I noticed some white scaling near the waterfall which I removed with a pumice stone. Equipment is a Pentair Variable pump, Pentair 150 Cartrige Filter, Rheem Hetpump, Pentair IC20 SWG with a Quikpure 3 ozonizer.

Since moving in 3 months ago, I purchased a Taylor K-2006 kit and found Pich A Penny to be accurate except for Stabilizer which I think is the same thing as CYA. My recent testing showed CYA at only 30, TA dropped to 55, and CH jumped to 400. I noticed very fast upward swings of PH despite my SWG set at 40% and the adding of Muriatic Acid 3x weekly. I got CYA up to 75, TH to 100, and noticed PH to hold much much better at 7.4-7.6 range.

Back to the staining! Pinch A Penny gave me a 3 part stain tester. I got FC down to 1.5 and Ph down to 7.2 to conduct the 3 part test, but all failed to show any changes. Is my FC still too high to test or do you suspect the staining cause from something else?

<a href="http://s1377.photobucket.com/user/Reachjoenow/media/2014-09-29101441_zps79d44ab2.jpg.html" target="_blank"><img src="http://i1377.photobucket.com/albums/ah61/Reachjoenow/2014-09-29101441_zps79d44ab2.jpg" border="0" alt="Pool Staining photo 2014-09-29101441_zps79d44ab2.jpg"/></a>