This is my second summer with a new all white fiberglass pool. It was installed in June and closed in late-September last year. Pool was closed by the pool company. During fall, winter and spring enough rainfall and snow filled the pool back up so I didn't have to add any water to it when I opened it.
The pool is surrounded by *many* trees and this spring, I litterally removed several cubic feet of wet leaves from the top of the pool winter net. After opening the pool, whenever I shocked it for the first few weeks, water would turn lime-green for a few days before returning to normal (not algae green, more like "kool-aid green"). I had the water tested for metals and phosphates and none were found. So I used the pool all summer and everything seemed normal after that. As time went by, I started noticing a light brown-green ring just below the waterline (so I thought) but the water seemed light-blue throughout the pool.
I just had the pool company come by this week to close the pool for the winter and now can see clearly that the entire pool has a very even beige tint everywhere that was under water compared to the few inches above that are still white as it should be.
The colour seems a little darker close to the water returns and a little lighter close to the skimmer at the other end of the pool. Also, inside of the skimmer there is no beige tint...
I have just found the subject of tannin staining in pools. Could it be that? Will it go away on its own during the winter? (I wish...) or if not, what can I do to remove it? Silly question: can ozone stain a pool? I have an ozone generator (and a chlorinator that will be replaced by a Stenner pump and liquid chlorine) and noticed that the clear plastic tube used at the ozone injection point into the pool plumbing has turned to a very opaque and dark colour after its second summer of use.
The pool is now closed and will remain so until next April, so at this point it's mostly curiosity but if my story rings a bell to anyone, I'd be interested in hearing about it. Note: the beige tinted fiberglass seems normal in all other aspects, it's shiny and I tried the vitamin C test and also a light scrubbing with a plastic scouring pad and it did not change anything.
I'm really glad I found this site and forum, I'm learning so much on the subject of pools and their maintenance but still have a some way to go.
Thanks for any help,
P.S. Pool chemistry: My CH was a little higher than I wanted thanks to faulty readings from my ColorQ, around 320-360 according to two pool stores. PH usually in the 7.6-7.8 range and ALK in the 100 range. I tried lowering the PH in the 7.4-7.6 range and ALK around 70 towards the end of the season to try to avoid the MA-sodium bicarbonate "yo-yo". CYA ranged from 0 to about 60 now (due to trichlor tabs). Sorry for the long-winded post, tried to provide a complete picture.