HarryCW Posted March 11, 2023 Report Share Posted March 11, 2023 (edited) I'm a spa newbie, zero experience, preparing to fill my new-to-me (old) spa for the first time. From my measurements, I'm guessing the tub's got about a 250 gal capacity. We have well water, with a chlorine injector system along with a 120gal contact tank, which deals with the iron bacteria and sulfur, followed by a whole-house carbon filter (w/ backwash capability), and then the softener. I do understand it's best to bypass the softener to fill the hot-tub to avoid "softened water" problems. Using a Taylor kit, I've measured the free chlorine in the water between the contact tank and the carbon filter, it reads between 1.5-2.0ppm at that point, and I've measured the free chlorine after the carbon filter, using my (more precise?) test kit for household water, and I get zero-ppm. No chlorine smell and no sulfur at that point, after the filter. My question is for people who understand these kinds of contact-tank systems.... how long does the treated water need to stay in the contact tank, in order for the chlorine to 'do its thing' at killing the iron bacteria? ie: How much, and how often, can I drain out of this 120gal tank in one go, before I'd simply be pulling untreated water through? Would it be best to only take out 75 gallons or so at a time, so the next filling of the contact tank has time to work? And then should I let it sit overnight, run the carbon-filter backwash, and then tap out another 75 gallons? Or does the contact tank need more time to treat the water than that? I did try filling the tub all in one shot a few months back (a "test fill"), and by the time it was full the water that was coming into the tub was smelling like sulfur. Is there a better way to do it? Thank you for any help! -- Harry Edited March 11, 2023 by HarryCW to clarify Quote Link to comment Share on other sites More sharing options...
HarryCW Posted March 12, 2023 Author Report Share Posted March 12, 2023 Now that I think about it, I wonder if the sulphur smell at the end of my "test fill" was only due to the carbon-filter needing a backwash. Is the time in the contact-tank really that important, or is simply mixing the Clorox with the iron bacteria enough to kill it? Thanks for any input. Quote Link to comment Share on other sites More sharing options...
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