Did I miss this discussion in the Pool School? I did read the Metal Stains topic.
My plaster warranty (quartz aggregate) says I need to maintain 10-12ppm of sequestering agent and states that "To help prevent metal stains and scaling of the finish and to up-hold your product warranty, you must add the proper amount of Sequa-Sol or any leading brand of sequestering agent weekly."
My CH is well below 200 right now (it's 110). My pool is 30 days old, just fired up the SWG last Friday. My plaster instructions say do not add calcium for the first 60 days. I thought CH affected scaling.
I don't think my tap water is hard (I haven't tested it and I will do that tonight). We don't have iron stains in our toilets, sinks, etc. or any problems like that.
I'm just confused on the reasoning behind adding weekly sequestering agent and I don't see that in the BBB method. and how do I test for it??