Super clorinate for vacation, or not?

[vangoghsear]

I ended up putting in 8 ounces of Clorox, set the temp down to 80, and locked the top.  When I got back there was still a 3 ppm chlorine rating showing on the dip stick.

Thanks for letting us know how it turned out.  Was this the older 6% Clorox regular bleach or was it the newer Clorox which is now 8.25%?  If it was 6%, then 8 ounces in 280 gallons would be 13.8 ppm FC.  Ending up with 3 ppm FC after 9 days is a loss of 15.6% per day at 80ºF.  That's actually pretty good considering that you have an ozonator since ozone breaks down chlorine so having it run a couple of hours twice a day must have been low enough to not be a problem..  In the future, if there were a way to keep the circulation but to turn off the ozonator, then the chlorine would probably last even longer losing less than 10% per day.  I assume that since you used Dichlor previously that you had some CYA in the water so that helped to moderate chlorine's strength.

I did still have some CYA about 40% I think.  It was much higher when I stopped the Diclor, but I added water a few times since switching to Clorox.  The Clorox concentration was 6% from the super market type.

[chem geek]

Just so you know, evaporation and refill doesn't reduce the concentration of any chemicals in the water since only water evaporates.  Some concentrations, such as Calcium Hardness (CH), can increase since any CH in the fill water gets added.  It's only water replacement, so a partial or full drain, that dilutes or removes what has been added to the water.  So your CYA was probably still pretty high though it does drop some over time, usually around 5 ppm per month though at higher CYA levels it may drop faster than that.

[deld]

That depends on whether the air is dry and/or windy and whether the tub is exposed to sun.  Low humidity and wind increase evaporation which would cool the spa.  If the tub is exposed to sun then it can heat up.  Exposure to just hot air without sun won't heat it up very quickly, but if the air is humid and calm then it might be OK.

Ah.  So during monsoon season it might, the rest of the summer really, really no. I'm guessing then that the 110* in the sun would be countered by the 10% humidity.

We had crazy humidity and rain this summer, during a really long monsoon season, but that was record setting and not at all normal.

Thank you!