Mbar, I found your excellent advice re: treating metal stains on vinyl liners with ascorbic acid on poolforum. Thanks! Hoping to do a little follow up here.
Background: approx 8 year old vinyl IG pool, 22K gals. Have been using metal-based systems (frogger, most recently eclipse-3) with it,
going to Eclipse about 3-4 years ago. Last year, in particular, a dark stain at the (6') deep end, maybe 20 sq ft. This year, it's bigger and perhaps darker, along with smaller stains in the shallow end. Vitamin-C in a sock lifted the smaller ones, so I followed mbar's advice.
The large stain got smaller (ie contracted from the edges) and got lighter in spots, so progress. A couple of questions:
- what's the max amount of ascorbic acid I can use? I already used around 4 lbs to get these results...I am not opposed to spending
some $ to get this cleaned up, but want to make certain I don't do some damage to the liner by getting the water too acidic. I lowered
the ph to around 6.5 before doing the ascorbic acid treatment.
- is it possible that given this developed over years, and has seen shock (which I think helps set the stain) that it is permanent?
- if more ascorbic and more time (say a day or two) is needed, is it safe for bathers to use the pool?
I did one treatment, and now have added the sequestering agent and am bringing the ph back up and will be adding the chlorine. Also plan to test to see if what's remaining is organic, rather than metallic. But if there's hope, I will take another run at this in a week or so. Otherwise I will probably deal with this 'til it's time to replace the liner.