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

[waterbear]

IT is possible that there is some biguanide remaining but if there was it would probably make the water a funny color. I would shock the tub and if the tub is outdoors I would add some stabizlier to the water, even with a cover on it. If you remove the cover during the day when the sun it shining it literally only takes minutes to burn of the chlorine! YOu could also use diclor in the tub instead of bleach but it takes a while to get a residual stabilizer so the chlorine holds. I don't use a cover on my tub, just a solar blanket. It doesn't keep the heat in as well but it is easier to put on and off! If your tub heats up quickly it is not an issue. I just turn mine on before I want to use it a and let it heat up. If your tub takes a while to heat this might not work for you.

I keep my tub around 5-6 ppm FC

[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!