Good morning. ChemGeek got me thinking about my planned spring conversion to SWG with this comment on another thread which I didn't want to hijack:
Recently, my pool water was tested by machine, not strips, at pool builder's store - tested 3500 salinity. They also tested my tap water to confirm 450 from tap/soft water source, from which I fill the pool.A standard water softener that is a cationic exchange resin will substitute calcium and magnesium with sodium so reduces water hardness, but does not change the chloride level and chloride is what gets measured in most salt tests. So yes SODIUM is increased with the water softener, but not chloride.
If you also had an anionic exchange resin, then THAT could substitute carbonate or bicarbonate for chloride and would be used to reduce high TA in fill water.
I have a dual tank softener; don't think its anionic.
Based on chrmgeek's comment, I took it to mean that my salinity reading is not necessarily related to the softened water. My salt buildup could be strictly from chlorine. Historically, I don't use a tonne of MA, but in past have used a to be of Jack's pink, then Metal Magic for previous iron load, which is now diluted to about .5 ppm or just under.
Likewise, the highest my TA ever runs is 90-ish, though pool is happier at 70. In 4 years I've never personally added TA, but on purchase original pool techs had.
I never tested for salt before and there was no evidence of a prior swg but I can reliably predict that the water was not likely lowered for winter etc (the same techs close it who built it and they don't lower the water due to water table for which they'd plumbed a sump.)
So apart from backwash not a ton of dilution. This is the first year that the water "tasted like a tear" and only since switching to the dual softener...the single unit would tap out on refills, meaning more well iron went in
Here are my questions:
1. Can high use of diphosphonic acid (eg Metal Magic) and its by-product of spent phosphate (to the order of about 25,000 ppb in attempted dilution) increase salinity...and more importantly, if I switch to swg, will it possibly create phosphate scale on the salt cell, reducing life span?
If so, is this one of the rare times a major phosphate floc is in order, and if so, what is the best, commercial-level/high volume remover to use with minimal contraindications?
2. Is it possible that sodium from soft water is skewing my salinity readings across the board? Or that the sodium is combining with my chlorine? Do I need to look into my softener setup further? Or just be happy that when I switch, I don't have to add salt?
3. Going forward, when I make the switch, assuming I stll have .5ish iron and .3 copper, will I have problems using Metal Magic to a maintenance level? Would I be better off switching to jack's magenta for swg?
4. Any other forseeable issues with the combo of metals, soft water additions, and SWG apart from manage salt build up if it gets too high?
5. My liner is about 15 yrs old and showing signs of wear...I don't plan to change it for two more seasons if possible, but when I do change it, I'm likely to have startup water trucked in to mitigate well/softener demand. Should I wait until the liner/water change to switch to SWG?
Thanks in advance for any insight