Hot Tub Water Smell like Chlorine

[rocky]

I think the chloramines in my indoor hot tub need to be reduced. The water smell like chlorine. Here are the results of testing the water:

Early morning of 17 Oct:

FC: 2.5
CC: about 0.7
pH: 7.8
TA: 80
CH: 150
Borates: 50
CYA: 30

The hot tub was filled (300 gallons) on 12 Oct. I have been adding 2 oz bleach (Chlorox 6 %) after each use. Normally, only 2 people use the tub and always after showering. The bleach has been used as a sanitizer but do I need to use something as an oxidizer?

In the evening of 17 Oct the FC had dropped to less than 0.5 . The CC was not measured. This was after 2 children had used the tub and had not showered. I shocked by adding 8 oz bleach.

18 Oct the FC was 4.5 and the CC was 1.0. Two oz bleach was added.

19 Oct the FC was 2.5 and the CC was about 0.7 ppm. I added 8 oz bleach.

20 Oct the FC was 7.5 but the CC was still about 0.7 ppm.

What are your recommended actions? I need to get rid of the chlorine smell. Water looks great but we know it is not.

Side question: Last year we did not use borates in the tub and did not have a foaming issue. This year we are using borates and there is much foam generated when the air from the blowers is maximized. Do borates in the water cause foaming and what can I do to eliminate this foam?

 

[spishex]

You can use bleach to get rid of the CC, but you'll need to add more (about 6 oz to get you up to 12ppm, then hold it there).

I'd wait until your CC is gone before you worry about foaming. If you still have an issue with it I'd bring the CH up to 200 or try to keep the pH a little lower (around 7.4). It will help if you keep all the air lines closed when no one is using the tub.

 

[BC]

Hi Rocky,
I shock weekly with MPS (non-chlorine) 1 oz. Try to keep my FC btw 2-4. Use Enzymes (scumbuster) once a week to help oxidize waste and bleach as a sanitizer (2 oz or so daily -depending on use).
I also added a mineral stick which also aids in sanitizing whle keeping FC at the lower limits. They last 4 months.
No chlorine smell and water stays clear with minimal foaming - no scum lines.
I'm going on 4 months without changing water and have used only around 5 gals of bleach.
Downside of using MPS - it's acidic so have to pop in an oz of Borax occasionally to keep the PH from dropping too low.

Barry

 

[rocky]

In response to the assistance provided by spishnex earlier today, I looked back at the water test data and saw I failed to provide some significant info. Here is a correction and the current test data.

At 6:30 AM on 20 Oct I reported the FC was 7.5 ppm, which it was. After that I added bleach to raise the FC and therefore get rid of the chloramines. What I failed to report is I added about 36 ounces of 6 % bleach. Somehow I miscalculated the necessary amount of bleach to add. When I tested the water this AM the FC was 21.5 ppm and the CC was about 0.7 ppm. I have had the cover off all day. I had the blower on for 4 hours. I tested the water at 2 PM and the FC was still 21.5 ppm. I did not measure the CC. I was surprised the FC had not dropped some amount. I plan to leave the cover off till the FC gets to a lower level. Any idea how to reduce the FC. Shouldn't the CC be less than 0.5 ppm after having the FC elevated for over 12 hours?

 

[chem geek]

Usually 2 ounces of bleach after 2 people using the tub would not be enough if it were hot (100-104F). The rough rule of thumb is 5 fluid ounces of 6% bleach for every person-hour of soaking. 2 ounces would only work for 2 people soaking around 12 minutes or so. So unless you were using additional oxidizer (or enzymes), I think you got behind and bather waste built up over time. However, your latest superchlorination should be able to accelerate getting rid of the combined chlorine. If it doesn't, then it's something persistent in the water. You could try a non-chlorine shock to see if it helps, but might need to change the water to get rid of it. It's strange, though, that it only showed up this time and not in the past -- sounds like the unshowered children may have introduced something into the tub (hate to blame them, though).

 

[rocky]

When you suggest a non-chlorine shock do you mean potassium monopersulfate? I use the TF-100 test kit to test the water. Will the reagents in this kit check for CCs?

I only measured the FC this morning and it was 17 ppm. The hot tub was uncovered and everything was off. At what level should the FC be before we can resume using the hot tub? Would it be 6 ppm?

 

[chem geek]

Yes, by non-chlorine shock I mean potassium monopersulfate (MPS). Unfortunately, the MPS itself will usually register as CC in the chlorine test -- very high levels, especially soon after addition, can also show up as FC. There is a Taylor K-2042 kit to remove the MPS interference, but this isn't always reliable. The MPS may not get rid of the CC either, but it's something you could try (see what happens after the chlorine level comes back down -- that is, is the CC still there and does it still smell).

Assuming you started out using Dichlor to get the CYA level up to around 30 ppm, then the chlorine level is equivalent to around 1.2 ppm FC with no CYA so on the high side. It's not unsafe, and some indoor pools have more effective chlorine than that level. You'll probably smell chlorine, but if you can wait until the FC drops closer to 10 ppm that would probably be a better experience for you. Up to you.