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

[keithw]

I ditched my Baquacil and switched to BBB in my stand alone hot tub yesterday. Threw out the Baqua-fied filters and got new ones. Cleaned it out real good shot water into all the jets, etc. It's 120gal fiberglass. According to the Bleachcalc I should be using real small quantities of bleach to get it to 5PPM, (1oz.) I have added at least 5oz and it keeps going right back to 0 hours later. Alk was off so I bumped it up. Will get complete test results tonight. But question is, could it be remanents of the Baqua still in the pipes that's killing the CL?

Has anyone who's converted a small hot tub over found BBB to be pretty stable? I am trying to avoid Bromine because I used to use it for years and it seemded to cause occassional rashes.

[Simmons99]

Is your hot tub exposed to sunlight? If it is then the chlorine is burned off by UV.

[keithw]

Sorry I shoulds have mentioned that. No it's not. I have a cover.

[RavenNS]

If you drained & refilled ( partially) & shot the water through all the jets, then drained the remenants, that should have done it ( gotten rid of the bacq).
The only thing I would have done differently is used a Tub Clean product first ( thats the stuff that you filter through before draining),
but by changing your filter, I would have thought that you did enough.

I use BBB, but I use bromine not bleach, so i guess I can't help you there.
Chlorine does burn-off faster at high temperatures ( than bromine).

Do you have some sort of stabalizer in the tub?
if you do, then keep adding chlorine slowly until you can maintain levels.

I think with chlorine, you want to shoot for around 7+ ppm
( but ask waterbear )

[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