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rob.montreal

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  1. Update: my FC further dropped from 13 to 9 and then to 6.5 over two consecutive 24h periods (no added chemicals, no soaking). So it looks like the spa is "eating" about 3-4 ppm per day when not used. My ozonator must not be very powerful indeed. I was expecting it to use up more chlorine. PH has also gone down to normal levels. I'll make sure I dump around 4ppm chlorine in there every day to keep it clean. That's 4oz according to the pool calculator. I'll keep a close eye on it for a few days to make sure FC doesn't accumulate again to ridiculous levels.
  2. Thanks, Chem Geek. It's a 450 gal and the bleach is 6% (says so on the bottle). I have definitely learned my lesson and won't add as much. I left the cover open for a couple hours on Sunday afternoon and FC had dropped to 16.5 by 9PM. I retested 24 hours later (cover closed, no soaking) and it had dropped to 13. So that must be my daily chlorine demand (22%). I was expecting more given the ozonator. But maybe it's not doing its job as well as I thought. PH has also started drifting down towards normal levels. It was at 7.8 last night. I haven't added any chemicals in the past 48 hours. Hope i find FC below 10 when i test tonight.
  3. This is really interesting and might explain the issue i'm having. TA at 50, but PH seems to be stubbornly high. The Taylor PH test maxed out last night and the acid demand test took 5 drops to get to normal PH. I added the required amount of dry acid, and tested again this morning (12 hours later) and the PH test maxed out again and required 2 drops on the acid demand test. Then I tested for CL and it's at 20PPM FC and zero CC!! Holy smokes! We haven't used the spa at all last week, but I have still added the usual 5oz of 6% bleach every night without even testing. Guess it added up and that's what's causing the false PH reading. I also tried a test strip just for fun and the PH pad is a very weird mix of orange and super bright pink. Guess I won't be adding any more acid until the CL drops to reasonable levels and I can test properly. Hope my ozonator gets rid of the CL in a few days. (I got about 20ppm CYA in there as well).
  4. Thanks! That's reassuring. The water is crystal clear and smells great (i.e. doesn't smell ) The night I wrote my previous post, I added 1.5oz of lithium without having used the tub (triple the dose the store recommended), which brought FC up to 9ppm. ~22 hours later FC and CC were both at 3ppm. This is without CYA. The CYA is still dissolving in a jug. Damn, it takes long!! Hope to be able to pour it into the tub this weekend and measure Chlorine Demand. The 50% loss you mentioned above, is that with or without CYA? I assume it's with CYA, right? Because I've been running without CYA so far and FC usually drops to zero by the next evening, even when I don't use the tub, unless I over-chlorinate the way I did this week. The specialist at the store told us that this is normal without stabilizer and that we should only worry about pouring in the recommended dose of lithium in the evening. (.5 oz/person). But I just never know if the zero FC is normal and due to the ozonator and lack of CYA or if it means that I didn't put enough to oxidize our waste. But it also drops when we don't soak, so that must mean it's the ozonator that depletes it. Hopefully starting on CYA this weekend will help me properly measure what's going on.
  5. Update: so i just tested the water again 22 hours after I chlorinated and both FC and CC are at 1ppm. That means the chlorine I put in last night oxidized / killed everything without running out and that my water is safe for use, right? Btw: i finally bought some CYA today. Dissolving it as we speak and hope to be able to pour it in before the end of the week and start using bleach. Thanks!
  6. Hi everyone. Newbie hot tub owner from Montreal, Canada here. I've had my 450 gallon Trevi hot tub for 3 weeks now and loving it. I am also really glad to have found this forum and the wealth of information you have posted here. We went away for 2 nights this weekend and I just want to pick your brains on whether I did enough to keep the hot tub water sanitized or if I should decontaminate and refill. Here's some background info and what I did before and after the weekend: The tub is 450 gallon, with an ozonator. I keep the water at 94 degrees. PH is 7.2 and ALK is 80. I sanitize it with chlorine (lithium), but without CYA. I only found this forum and the dichlor+bleach tutorial after I had bought my chemicals, and I haven't had the time to go back to the store and buy CYA. I plan on starting that next week. The night before we left, I chlorinated to 10ppm. The tub had not been used that day. The next morning I still had 5ppm of free chlorine in there. I didn't add any more chlorine that morning, but dropped 4 bromine tabs in a floater, opened it to the max and put in in the tub. Then we left and the tub was alone from Saturday morning to monday evening. The power was on, so the ozonator and filtration cycle (8 hours / day) ran during our absence. Last night when I got back, there was zero FC (which I believe is normal since there's no stabilizer), zero bromide and the bromine tabs were barely showing any sign of use. Combined Chlorine was at 1 ppm. The water was crystal clear as always and smelled clean. I ran both pumps on full speed for a few minutes and there was no weird stuff coming out of the pipes and no foaming in the water. PH was still 7.2 and ALK was down to 60. I removed the bromine floater and added 4 tablespoons of lithium, which shocked the tub to 17ppm FC. Kept the cover up for about half an hour and ran both pumps full speed for about 10 minutes. I forgot to check the FC this morning to see how much was consumed, but I'll check it tonight and report back. Based on all of the above, do you think that was enough to keep my tub water sanitized or should I drain and refill? Like I said, the water looks and smells great. On a different topic: before I found this forum I took a mandatory spa maintenance class with the manufacturer. They recommended that we sanitize with unstabilized lithium: 1 tablespoon per user each evening, up to a max of 4 tablespoons a day. On days when the tub is not used, just add 1 tablespoon. They specifically told us to not use any stabilizer because "it will damage the headrests". Does that sound like a valid reason, or are they just trying to make us use more lithium and thus buy it more often? (The spa manufacturer has their own store and sell their own chemicals at a pretty steep price). I honestly would like to go the stabilizer+bleach method as it is not only cheaper, but will also allow me to measure FC accurately. The way it is now, FC is always 0 the next day and I never know if that's only because of the ozonator, or because I didn't put enough to oxidize all human waste. Many thanks! Robert.
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