I have a customer with a 10,000 gallon 10x30 rectangle indoor vinyl liner IG pool using a Zodiac Duo-Clear SWG, heated with a Lochinvar ERL 152-8009 gas fired pool heater. My only involvement here was in 2010 when I replaced the liner, installed the SWG and heater. I looked at the pool this past Monday 9/14/15 because the liner is pulling out of the track at one of the 2' radius corners and the heater is boiling water and banging. My observations are:
Water tested with a TF100 test kit purchased from this website in June of 2015:
CYA < 5 (barely present, she added 1/2 pound because the bottle said "conditioner"
A local pool store has been selling her the salt and testing the salt level for her. I don't have a test kit for salt and really don't know salt systems. I read the stick re; SWG, that didn't answer my questions.
The liner is pulled out of the track for about 16" in one of the radius corners because there's nothing left of the lip that the liner bead locks into. The inside of the track is packed full of with crystals, from the size of sand to some as large as 1/4" in diameter, irregularly crystalline shaped, off white slightly brownish in color. I tasted one, it tastes a little salty but not biting like a piece of rock salt. The coping is anodized extruded aluminum and there are actually 6 - 8 small holes eaten through the coping along that 16" section of the 2' radiused corner, from 1/32" to 1/8" in size. This coping corner sounds hollow when tapped on, the other three corners do not. There is no other signs of corrosion to the coping other than in this corner. She adds salt to the pool at the end that's opposite this corner.
The owner gave me a small bag of scale pieces, some as large as 1/4" at about 1/32" thick, slightly curved (like the inside of a heat exchanger tube) that she collected from the bottom of the pool below the returns, she said it only sends this scale into the pool when the heater is running. She hasn't run the heater at all this summer because of the banging.
There is evidence of light brown staining to the liner and especially at the white returns. The owner agrees that she has a high mineral (iron) content to her makeup water.
1) Is SWG appropriate for an indoor pool?
2) Is CYA appropriate for an indoor pool when used with SWG?
3) Is the salty water corroding the aluminum?
4) If the water is corrosive, can it also be scale forming in the heater's tube bundle heat exchanger?
5) The heater Mfg says CA up to 350 is acceptable. Change some (or most) of the water to drop it from it's present 425?
6) Is there any way to measure for or determine electrolysis, ie; possibly the pool and coping isn't grounded or bonded correctly?
7) Any tips on cleaning a heat exchanger cupronickel tube bundle in or out of a Lochinvar ERL 152-8009?
Thanks for any input! This is a tough one for me.