Sorry for the delay... I have been in Europe for the last two weeks.
So my FC and TC #s are back in control at 2.5 and 0.5 ppm. This is normal for my SWG so we are in good shape. Now I have to get back at the stains.
Thanks for everyone's help!!
Michmike - Any time I have small brown or blackish organic stains on the bottom of the pool that brushing doesn't remove and my plastic components (like my automatic pool cleaning robot, outlet nozzles, skimmer baskets, and drain covers) turn yellowish brown I have been able to eliminate them with Ascorbic Acid (a.k.a. Vitamin C). I get the AA at Warehouse Pools for about $50 per lb and 0.5 to 1lb is all you need to add. If you follow the Ascorbic Acid treatment steps in the Pool School you will get some good results. The key is to take your FC to 1 or lower otherwise the AA will react with that first before the stains. Once I add the AA the stains leave in about 30 minutes. Then you have to bring the FC back up slow. That's where I got in trouble this year. I had high TC and so when I dropped my FC for the AA treatment the algae bloomed and I had to shock the pool, which turned my plastic yellow...a viscious cycle.
By the way I have some scaling from letting my ph stay too high this winter which has taken on a slightly offwhite coloring. I am keeping my ph low and brushing until it goes away. Other than that I have never had a stain that AA didn't eliminate. We even had our roof redone after a hail storm and the roofers dropped nails in the pool that stained the plaster. AA took it right off - no scrubbing, brushing, nothing but adding it in a filtering. Make sure you turn off your SWG though while you wait for the AA to work. I have done it in the past and once the stain leave I just turn the SWG back on and within a day the FC level is holding.
Hope that helps.