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Thread: Last Summer's pool water clarity questions... rust from old heater and SWG?

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    Join Date
    Apr 2015
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    Western, WA
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    Last Summer's pool water clarity questions... rust from old heater and SWG?

    Hello,

    Last year was our second year with our 16'x48" Intex pool. I struggled way more in 2016 than in 2015 maintaining water clarity. There were two significant changes to the equipment I used and I'm wondering what impact they may have had on water clarity. First I purchased a used Laars 250kBtu/hr heater and used it from the end of March through September. Its old, but works quite well and gave us very nice swimming temps all summer. However, I think the heat exchanger is slowly rusting. Second, in July I added an Intex Salt Water Chlorine Generator. All was perfect after this addition for about 4 days--it was crystal clear. Then it became green/brown murky (not horrible, but compared to what I was used to it was bad) with brown stuff settling in patches on the floor of the pool. It seemed that no amount of running the filter/SWG/adding bleach could help me. At the time I thought it was an algae issue, but now I'm beginning to think much of it could have simply been rust from the heater's exchanger and that adding salt to the system only made the rust rate increase--thus clouding my pool.

    Can this be right or am I way off in my theory?

    So, what is the solution?

    I'm considering swapping out to a larger pool this spring. If my heater is rusting this bad (and causing this problem) I'm thinking I should just pony up and buy a new heater (absolutely needed here in Western Washington with a shady back yard) with the Cupro-Nickle heat exchanger so as to not have to deal with the rust. We are on city water and it does not have iron in it.

    Curious what others have experience with aging heaters, rust and SWG's.

    Thanks!
    AG Intex Ultra Frame 26'x52". TF100 test kit. Intex 3,000 gph sand filter/pump, Solar Cover, Intex magnetic pool light, Hayward Skimmer, Raypak 400kbtu/hr. Intex SWG.

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    Mod Squad Texas Splash's Avatar
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    Jun 2014
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    South-Central Texas, Marion/San Antonio
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    Re: Last Summer's pool water clarity questions... rust from old heater and SWG?

    It sounds as if your heater has contributed to the iron problem you're seeing in the water. The addition of your SWG and consistent generation of FC may have also triggered the iron's reaction with the chlorine causing the water changes. Once iron gets in the water, it's in unless you can manipulate it into a suspension form and try to filter some of it out. Otherwise you need to use a sequestrant to keep the particle suspended in the water which helps to prevent settling and staining. In the end, replacing the heater would be a good option.

    Not knowing the history of the heater or your water chemistry makes a true diagnosis difficult. You have a TF-100, so hopefully the water has not been too corrosive with a low pH which would enhance corrosion. If you're going to get a new pool soon anyways, I definitely would get a new heater. Once you have the fresh water in the new pool, this iron mess should be behind you.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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    Join Date
    Apr 2015
    Location
    Western, WA
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    Re: Last Summer's pool water clarity questions... rust from old heater and SWG?

    Thanks Texas Splash. PH was fine. The entire time I believed I was dealing with an algae issue so brought the pool up to slam levels and watched it but saw no improvement in appearance (algae die-off) like I've seen in the past, so was quite perplexed. The only thing that helped me clear it up was turning the pump off, letting things settle, then vacuuming the floor out of the pool (not through filter as the sand filter would not trap it). After doing this several times over several days it got better, but I could see greenish brown water coming back into the pool through the return with the pump running. I assumed again that the sand filter was simply not capturing what I thought was dead algae, but now I suspect it was rust particles coming from the cast iron headers on the heater's exchanger. Also, I have my SWG downstream of the heater with twelve feet feet of pipe in between, but I do not have a check valve in that section of line which I probably should have.
    AG Intex Ultra Frame 26'x52". TF100 test kit. Intex 3,000 gph sand filter/pump, Solar Cover, Intex magnetic pool light, Hayward Skimmer, Raypak 400kbtu/hr. Intex SWG.

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