Help! Vacation requires figuring out Trichlor Chlorinator Settings

[MBMMPool]

Hello, All. On my 3rd summer with a vinyl lined ~25,000 Gallon Pool with Autocover. I have operated the pool per the TFP-endorsed BBB method throughout all operating seasons, and couldn't be happier with my results. Use a test kit regularly, and have been averaging ~.5 ppm loss of chlorine per day when unused/short use... Getting ready to leave for a 12 day family vacation- pool will be covered, and pump running 24/7. I figured this is the time to finally use the Hayward CL-220 Chlorinator that my installer provided, so I decided to run things overnight last night to confirm the Settings. My plan was to check Chlorine level at 12 hours, then 24 (which I never got to) and shoot for a setting that provided me with ~.5 ppm over a day.

The Hayward Manual suggested 10 3" Trichlor Tabs, and a setting of "3" on (with "10" being maximum Chlorine, "0" = Off). Of course, there suggestions are likely for an uncovered pool, so I decided to let things run with set at only "1" and measured my Chlorine levels (FAS/DPD) just prior to loading the Chlorinator. Starting FC - 0.5 ppm yesterday evening (90+ degree sunny day, kids and friends had been swimming all day). When I awoke this morning, I measured again and was shocked to see my levels were up to 4.5 ppm after only 12 hours of running. I turned the thing to "Off", and remeasured this evening (still at 4.5, with no pool opening/usage today, so at least "Off" is "Off" on the Chlorinator).

Does this sound reasonable, or might something be wrong with my Chlorinator? Does anyone out there have a ~25,000 G Pool + Autocover that could suggest some settings? I'm thinking I'm going to need to pool several of the Trichlor tabs OUT of the feeder, as it really can't be turned much lower... Only have a few days to figure this out (leaving for vacation Monday), and kids would likely be swimming so I don't can't have my levels going much higher in the short term. (Current CYA Level is ~25 ppm, as I've consciously let this remain low this summer knowing that I'd be using tricolor for a couple of weeks).

 

[anonapersona]

!Not too surprised at the high level with a cover on. You will want to load less tabs. It can be really hard to remove the tabs from the feeder but you should try. It will still be adding chlorine even with the unit off, or at least my Rainbow does.

I see a few choices here. Either unload it or turn it down further and keep testing.Try maybe two or four tabs. Leave the cover of to help run your FC down so you can start the test again. Or don't and just keep testing as you try to reduce the level it is putting out.

Pool Math will tell you how much FC you will get from each tablet. I'll guess a bit more than 1 ppm each, so two tabs ought to last 4 days, maybe 5 days. So it may be that 4 will be the right amount for 12 days. Note the CYA levels you will have at the end of the tablets you've loaded.

Also account for the drop in TA. You may need to push that up just a bit if you are at a low value now. Check with Pool Math but I think you may lose about the same amount of TA as you add in FC.

Overall with a cover on it ought to be OK even if all the tabs dissolve at once if the total FC added is below mustard shock level. But I'll bet 10 tabs is to much.

 

[Abigail K]

I can't really help with the settings, but as you've found out, those things don't give you fine control over the dosage rate. You can try taking some tabs out of the feeder and experiment to see which setting gives you the dosage rate closest to your requirements...

You could probably try taking your pool up to SLAM and cover it before leaving. Also, if you SLAM and cover, it won't be necessary to have the pump running 24/7.

 

[MBMMPool]

!Not too surprised at the high level with a cover on. You will want to load less tabs. It can be really hard to remove the tabs from the feeder but you should try. It will still be adding chlorine even with the unit off, or at least my Rainbow does.

I see a few choices here. Either unload it or turn it down further and keep testing.Try maybe two or four tabs. Leave the cover of to help run your FC down so you can start the test again. Or don't and just keep testing as you try to reduce the level it is putting out.

Pool Math will tell you how much FC you will get from each tablet. I'll guess a bit more than 1 ppm each, so two tabs ought to last 4 days, maybe 5 days. So it may be that 4 will be the right amount for 12 days. Note the CYA levels you will have at the end of the tablets you've loaded.

Also account for the drop in TA. You may need to push that up just a bit if you are at a low value now. Check with Pool Math but I think you may lose about the same amount of TA as you add in FC.

Overall with a cover on it ought to be OK even if all the tabs dissolve at once if the total FC added is below mustard shock level. But I'll bet 10 tabs is to much.

Thanks a lot- this makes sense. I should've started with the Pool Math instead of the generic "Owners Manual" recommendations. Used some old "tongs" for the grill to remove 6 of the tricolor pucks.