Going on vacation in 1 month

[morzh]

my whole family is going vacationing for 2 weeks.
Usual question, what do we do about the pool?

So far my FC decline rate is under 1 ppm a day due to a fairly high CYA = 77.
So when I dump a gallon of it at 8.2% strength into the pool (26K gallons), three days after I still read between 5 and 6ppm.

Now if I dump a whole lit of it, the devline rate will increase as it is dependent (I think exponentially) on the init qty, so I am not sure if this is a good solution.

I could possibly temporarily revert to tab clorination (I have an in line chlorinator still though it is empty) but then it will raise my CYA which I think is higher than I'd like in the 1st place.
I wonder by how much it would raise it, if by 4-5 ppm over two weeks, I can take that but I fon't know that.

Any other good practical way? Short of asking neighbors?

 

[Texas Splash]

For the CYA question itself, I found these two quotes from some of our long-time resident experts:

Pucks come in different sizes. Common are 7 & 8 oz sizes. An 8 oz tablet will raise your FC by 2.2 ppm and your CYA by 1.3 ppm in a 25,000 gal pool.

For dichlor every 1 ppm of chlorine you add also adds 0.9 ppm of CYA.

In addition, the bottom of the Poolmath calculator gives some info on the effects of adding chemicals such as trichlor and dichlor. Still, the ultimate results of using tabs for a long period of time may depend upon the flow rate of water across your in-line chlorinator. Hope this helps you a little.

 

[JoyfulNoise]

For every 10ppm of FC delivered by your feeder (39oz of trichlor, ~ five 3" pucks)you CYA will increase by 6ppm.

A single 3" puck typically weighs 8oz.

How many pucks do you estimate you would use in 2 weeks?

Can Friends or neighbors help?


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[chem geek]

So far my FC decline rate is under 1 ppm a day due to a fairly high CYA = 77.

You must not have a full day of sun on the pool or you have a pool cover since that's a fairly low loss rate. If I assume that you keep your FC at a minimum of 6 ppm and you go from 7 ppm to 6 ppm over a day, then this is a daily loss rate of 1/6.5 = 15%. If you were to raise your chlorine level to say 15 ppm FC, then after 7 days you would end up with 15 * (1-0.15)^7 = 4.8 ppm which isn't so bad, but after 14 days you'd only have 1.5 ppm FC which is too low so during the second week algae may grow and your chlorine loss rate increase (i.e. chlorine get used up).

Using an in-line chlorinator set for roughly 1 ppm FC per day output would after 2 weeks increase CYA by 8.5 ppm. While not great, that's probably an easier option assuming you can put enough Trichlor pucks into your inline chlorinator. It would take 6-1/2 3" 8-ounce pucks to provide 14 ppm FC in your 25,300 gallon pool.

 

[JoyfulNoise]

Since you're in NJ, water replacement, while no fun, is an option for you (unlike folks in CA). If you have a month to prepare, then I would spend some time draining and refilling the pool to get your CYA down to 50ppm. That would then give you the stabilizer "headroom" you need to pack your inline chlorinator and perhaps one or two blue puck floaters so that you can go on vacation and not come home to a green mess.

I would also consider doing a SLAM or at least raising your pool to shock levels a day or two prior to leaving so that you know you're leaving the water as clean as possible before you go. Between raising it to shock level and having extra pucks running, you may just make it through the 2 weeks without a problem.


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[morzh]

I think 4 to 6 tabs will last 2 weeks there before having fully dissolved, in the past they were at the almost max open which was 3-3/4 setting.
So I might set it lower (my initial experiment was me lowering the setting to sub-1 and seeing no appreciable decrease and 2 weeks after I put tabs in there were still some left) and dump maybe 3-4 gallons night before we leave just to sterilize potential offenders.
If it raises my CYA by 10-15 points, well it was 91 vs now 77 and I was OK, so....I will deal with it when I come if I even have to.
Might just work.