I own an IG "low-hung" 18 x 36 pool (est. 28000 gal) with a sand filter system. I just received my TF-100 today and my readings are...
Temp - 86
My water is crystal clear. I use liquid chlorine and I also have an auto chlorinator but I have turned it off as of two days ago (seems like they aren't a good idea from what I have read on this site). I know the chlorine is high, not sure if this is why the T/A is so high...? I started bringing the chlorine up because I am planning on shocking the pool but wanted to run the tests of the new kit before I shocked it.
My actual question is this. I have a problem with a yellow stain-like substance on portions of the both floor and walls of the pool. It started last year and will come off with a brush. I shocked the pool a couple of times last year and it seemed to have little effect. When we opened this year everything was fine and remained that way for the first month or so, now - right back to the same game. I am not sure if this is a form of algae or some kind of metal staining but it is getting VERY frustrating. I have even considered that it may be pollen, but I think it is too much and it "grows" even on a calm day when we have the solar cover on. What is the best way to tell what this is? Any help would be GREATLY appreciated.
Please let me know if I have left any important info off of this post and I will answer quickly as I am planning on shocking the pool tonight as a first step.
Thank you for your help and this resource.