I BBBed my hot tub , but it won't stay

[Bppool]

Just a thought, 120 gal sounds pretty small, I have a 120 gallon aquarium and there is no way a person could get in it...

[waterbear]

Just a thought, 120 gal sounds pretty small, I have a 120 gallon aquarium and there is no way a person could get in it...

My hot tub manufacturer says mine is 280 gallons. I estimate that it actually has about 250 gallons of water in it and it will seat 5 comfortably. (manufacturere says it seats 6, only if they are VERY close friends!)

[keithw]

Yep it's a 120 gal. It's a three seater. I wanted the smallest that I could find since it's primarily only me in it. I hadn't added any stablizer because it is always covered. Should I even thought it receives no UV?

[EricF]

I would not put in stabilizer, as even at low levels it dramatically reduces the effectiveness of chlorine to control pseudomonas aeruginosa, which can cause serious skin infections. This is a bacteria that thrives at hot tub temps. You will be able to find more info by googling "pseudomonas", "cyanuric", and "spa" at the same time. You can also check out this link:

http://www.dsf.health.state.pa.us/he...a=180&q=234664

It is also interesting to note that pseudomonas is one of the bacteria that can break down CYA and use it as food!

EricF

[chem geek]

For those interested in the quantitative reduction in chlorine's effectiveness at different levels of CYA, see this chart and this graph. These were done at 80F, but there isn't that much difference at the hot tub temps of 104F.

The rough basic rule (applicable when CYA is larger than FC) is that at a pH of 7.5 CYA reduces the disinfecting/oxidizing form of chlorine (HOCl) by a factor of 75% of the CYA level. So, a CYA of 30 ppm reduces chlorine's effectiveness (compared to no CYA) by a factor of 0.75*30=22.5 so that the killing form of chlorine is reduced to 1/22.5th of its concentration compared to no CYA.

Richard

[waterbear]

IF you use the hot tub during the day or have it uncovered for any reason during the day I would put in CYA. The most commen form of chlorine for hot tubs is dichlor. This is what is usually recommened by hot tub dealers when you go on a chlorine system. Dichlor is stabilized chlorine so it will add cya to the water. My hot tub is chlorinated by my SWG and has a CYA level of 70 ppm. If you maintain a steady FC level in the tub like you do in your pool there should be no problems! It's when people ignore the tub and only chlorinate it when they use it that it becomes a bacterial stew!

[EricF]

Thanks Evan,

I agree that maintaining steady, proper chlorine levels is THE MOST IMPORTANT thing, but I am still leery of the reports various health departments and the CDC linking pseudomonas infections and cyanuric acid use in spas.

This quote from the Pennsylvania Dept. of Health in my previously cited source is telling.

"Should cyanuric acid be used in hot tubs or spas? – At even moderate levels of cyanuric acid, the amount of time it takes chlorine to kill pseudomonas aeruginosa (the bacteria that causes “hot tub itch”) can be as much as a hundred times as long as in a hot tub or spa without cyanuric acid. For this reason, the Pennsylvania Department of Health does not recommend the use of cyanuric acid or stabilized chlorine in any hot tubs or spas."

Also see this link:

http://www.cdc.gov/mmwr/preview/mmwrhtml/mm4948a2.htm

I admit the outbreak occurred in these PUBLIC spas primarily due to lack of chlorine, but they still warn about an association with CYA. I admit, in private spas this may not apply at all. But having seen the effects pseudomonas can have on patients, it is something I am very sensitive to.

I use a SWCG in my pool, but have a standalone hot tub in which I use BBB. In my case, adding a small amount of bleach every other day works fine when it is covered during the day to keep my levels above 4ppm without CYA. If it is going to be used during the day (which I admit, is rarely), I double or triple the dose, but still it is just a few ounces of bleach in a 600 gallon spa to maintain adequate levels.

Any thoughts? Just trying to stimulate discussion.

Thanks,

EricF