Combined chlorine

[Tembroke]

I'm a new hot tub owner, and I've been reading the sticky threads and trying to follow all the instructions, but I'm still uncertain on a few points.

Here's my situation:
I have a Caldera Salina with the Watkins Saltwater system (420 gallons).
I've been using it for less than three weeks.
My chlorine source is the SWG, but I supplement with dichlor as needed and then switch to bleach after I've added ~30PPM CYA via the dichlor.
I use test strips for quick checks (e.g., to verify that some free chlorine is present), but use a Taylor FAS-DPD test kit to double-check it and get more precise readings.

After my first fill, we used the hot tub a lot and the combined chlorine level reached ~2.0PPM in less than two weeks. I tried super-chlorinating, but it didn't seem to help, so I used Ahh-some, emptied, and refilled.

For my second fill, I balanced to ~70TA and added 40PPM borates for Ph stability. In less than a week of use, combined chlorine was back up at 0.5-1.0 (as measured using the Taylor kit). I understand that the solution to combined chlorines is to superchlorinate at 10PPM or greater, so I added 2 tablespoons of dichlor (raising FC to roughly 12PPM) and turned the SWG off temporarily. 18 hours later, FC is 6PPM and I'm still measuring 0.5-1.0 combined chlorine. Ph is 7.5.

What should I do now? Is there any way to get rid of combined chlorines without making the hot tub totally unusable for 1+ day per week or spending a fortune on MPS?

 

[wireform]

Tembroke
When are you checking the CC. The cover needs to be open for about 30 minutes before you check to outgas the CC.

 

[Bperry]

I'm a new hot tub owner, and I've been reading the sticky threads and trying to follow all the instructions, but I'm still uncertain on a few points.

Here's my situation:
I have a Caldera Salina with the Watkins Saltwater system (420 gallons).
I've been using it for less than three weeks.
My chlorine source is the SWG, but I supplement with dichlor as needed and then switch to bleach after I've added ~30PPM CYA via the dichlor.
I use test strips for quick checks (e.g., to verify that some free chlorine is present), but use a Taylor FAS-DPD test kit to double-check it and get more precise readings.

After my first fill, we used the hot tub a lot and the combined chlorine level reached ~2.0PPM in less than two weeks. I tried super-chlorinating, but it didn't seem to help, so I used Ahh-some, emptied, and refilled.

For my second fill, I balanced to ~70TA and added 40PPM borates for Ph stability. In less than a week of use, combined chlorine was back up at 0.5-1.0 (as measured using the Taylor kit). I understand that the solution to combined chlorines is to superchlorinate at 10PPM or greater, so I added 2 tablespoons of dichlor (raising FC to roughly 12PPM) and turned the SWG off temporarily. 18 hours later, FC is 6PPM and I'm still measuring 0.5-1.0 combined chlorine. Ph is 7.5.

What should I do now? Is there any way to get rid of combined chlorines without making the hot tub totally unusable for 1+ day per week or spending a fortune on MPS?

Are you using MPS in the tub?

 

[Mdragger88]

What should I do now? Is there any way to get rid of combined chlorines without making the hot tub totally unusable for 1+ day per week or spending a fortune on MPS?

It is fine to use the tub w/ fc anywhere between minimum & slam level for your cya.
The bodies will lower the fc pretty quick.
If you have been using mps it can show up as cc’s unless you use interference regeant.

 

[Tembroke]

Thanks for the replies!

Responding to all the questions:

Re:MPS — I haven’t used any MPS yet during this fill.

Re:FC — It’s very helpful to know that high FC levels are ok. I was worried that it would be too irritating, and that I should wait until FC levels fell to 5-6PPM before using.

Re:Offgassing — I checked the CC twice earlier today. The first time I got 1.5PPM and the second time (10 minutes or so later) I got 0.5-1.0PPM.

In order to be sure I had a valid reading, I took off the cover, waited an hour, and redid the measurement just now. I got 4PPM FC and 1-1.5PPM CC. (The water had a slight pinkish tinge after two drops that disappeared with the third drop.)

So unless I’m measuring wrong, I have a rather high CC level after less than one week, and my attempt to SLAM totally failed. Am I missing something?

 

[Mdragger88]

Thanks for the replies!

Responding to all the questions:

Re:MPS — I haven’t used any MPS yet during this fill.

Re:FC — It’s very helpful to know that high FC levels are ok. I was worried that it would be too irritating, and that I should wait until FC levels fell to 5-6PPM before using.

Re:Offgassing — I checked the CC twice earlier today. The first time I got 1.5PPM and the second time (10 minutes or so later) I got 0.5-1.0PPM.

In order to be sure I had a valid reading, I took off the cover, waited an hour, and redid the measurement just now. I got 4PPM FC and 1-1.5PPM CC. (The water had a slight pinkish tinge after two drops that disappeared with the third drop.)

So unless I’m measuring wrong, I have a rather high CC level after less than one week, and my attempt to SLAM totally failed. Am I missing something?

Keep slam level until cc’s are .5 or below. This can take a couple rounds. Also leave the cover off after use & dosing so that cc’s outgas (this is helpful for the longevity of your cover & headrests too).
Did your purge produce anything? I always do 2 consecutive purges now w/ the same water using a 1/2 dose for the 2nd to be certain it’s good to go after i had an “experience” with some residual funk.

 

[Tembroke]

Keep slam level until cc’s are .5 or below. This can take a couple rounds. Also leave the cover off after use & dosing so that cc’s outgas (this is helpful for the longevity of your cover & headrests too).
Did your purge produce anything? I always do 2 consecutive purges now w/ the same water using a 1/2 dose for the 2nd to be certain it’s good to go after i had an “experience” with some residual funk.

Thanks, Mdragger88.

The Ahh-some purge produced a little brown gunk, but not nearly as much as I expected. I’ll do it twice next time I drain.

I’m trying to slam again now — I just put in 12oz of 7.5% bleach, which should add 19ppm FC. And I’m leaving the SWG on this time (set to level 8/10), so that it will maintain a high FC level. Maybe overkill. We will see.

How long do you usually leave the cover off? 10 minutes? 30 minutes? Hours? Longer for slam?

It’s 33 degrees F outside so I don’t really want to leave the cover off for hours and hours if I can avoid it…

 

[Mdragger88]

I try to do 30 minutes after adding chlorine or soaking (which generally coincide). Also on warm sunny days I will periodically leave the cover open for an hour or so so things can “air out” & i can rinse & sun the inside of my cover. Going much beyond slam level for your cya is not recommended as it risks your equipment/ surfaces.
The key is really maintaining the slam level until unwanted cc’s are eliminated.
I find I have persistent cc’s of .5 as I near purge/ water exchange time.

 

[Bperry]

Thanks, Mdragger88.

The Ahh-some purge produced a little brown gunk, but not nearly as much as I expected. I’ll do it twice next time I drain.

I’m trying to slam again now — I just put in 12oz of 7.5% bleach, which should add 19ppm FC. And I’m leaving the SWG on this time (set to level 8/10), so that it will maintain a high FC level. Maybe overkill. We will see.

How long do you usually leave the cover off? 10 minutes? 30 minutes? Hours? Longer for slam?

It’s 33 degrees F outside so I don’t really want to leave the cover off for hours and hours if I can avoid it…

What kind of bleach did you find with only 7.5%? It’s getting harder to find bleach without other additives so be careful to make sure it’s plain bleach, no cloromax technology, fabric softeners, etc. You may already know that but figured it’s a good reminder.

 

[Tembroke]

I’m using HDX (Home Depot Brand) germicidal bleach, which doesn’t seem to have any additives. I already made the Cloromax mistake during my first fill, and learned from it.

 

[wireform]

I’m using HDX (Home Depot Brand) germicidal bleach, which doesn’t seem to have any additives. I already made the Cloromax mistake during my first fill, and learned from it.

Good stuff

 

[Bperry]

I’m using HDX (Home Depot Brand) germicidal bleach, which doesn’t seem to have any additives. I already made the Cloromax mistake during my first fill, and learned from it.

Ok, I think they brand the good stuff “chlorinating liquid” and I use that. Unless they have two kinds. If they don’t, they should have 10% gallon jugs for about $4. Might be a better deal than the 7.5%.

 

[Tembroke]

CCs are still >0.5ppm, so I’m continuing to add bleach every 6-12 hours, and leaving the cover off for substantial periods of time. Also, Ph crept up to >8.0, so I added 1.5oz muriatic acid.

I’m looking forward to the day when I can go 24 hours without counting drops and comparing colors!

 

[Newdude]

I’m looking forward to the day when I can go 24 hours without counting drops and comparing colors!

PH is invalid at 10+ FC. It gives a false high, which is why we lower PH to start the SLAM, so its good for the duration.

 

[Tembroke]

PH is invalid at 10+ FC. It gives a false high, which is why we lower PH to start the SLAM, so its good for the duration.

Ah. I see. Good to know. I thought I had done enough reading and was prepared for this, but apparently not.

 

[Newdude]

I thought I had done enough reading and was prepared for this, but apparently not

There is sooooooo much info to be had here, nobody processes it all the first few tries. All these newfound scientists are so preoccupied that they could, they fail to realize if they should.

Ask me how I know.

 

[Tembroke]

I've been slam-ing for a couple days now and the CC reading hasn't changed at all. It's always in the 0.5-1.0 range -- the 10ml CC test remains slightly pink after adding a single drop and goes completely clear after two drops. This happens even when I leave the cover off for a while and wait before performing the test.

What does this mean?
* Am I doing the test wrong? Should I switch to the 25ml (0.2PPM/drop) test?
* Is my tub somehow extremely dirty? Do I need to change the water again? (I've had it for less than a month, and I've already used Ahh-some and changed the water once.)
* Should I just keep FC in the 6-12 range indefinitely, until the CC reading is < 0.5?
* Should I just accept 0.5 CC as a baseline and not worry until it goes higher?

I'm confused and frustrated. But maybe everything's fine and I should just ignore it? Any advice?

 

[Newdude]

Am I doing the test wrong? Should I switch to the 25ml (0.2PPM/drop) test?

You are doing great. Switching to 25 will make you a little more precise but waste 2.5 X the drops. .5 is plenty close enough.

Is my tub somehow extremely dirty? Do I need to change the water again? (I've had it for less than a month, and I've already used Ahh-some and changed the water once.)

I don't see how it is at this point. Hang tight for @Mdragger88 thoughts.

Should I just keep FC in the 6-12 range indefinitely, until the CC reading is < 0.5?

Yes. Or equal to. At least with the spa, you aren't vacuuming and babysitting the filter. So you have that going for you, which is nice.

Should I just accept 0.5 CC as a baseline and not worry until it goes higher?

.5 is always 'ok'. There will always be some small iota being sanitized, and the test has error as well. Between the 2 of those, .5 is a pass.

 

[Mdragger88]

Like newdude said .5 cc’s is perfectly acceptable (as a hot tub is always going to be considered people soup).
Before u test next time try cleaning your test tube with alcohol & a paper towel as a dirty tube can affect the cc test.
Did u remove the head rests & check/clean them? If not do so (if u have them)
Also make sure there’s not a leaf or something random in the filter compartment that the fc is steady working on. Some people have found interesting things in there on occasion.
I understand you not wanting to babysit the slam level but just be sure you always maintain fc above minimum for your cya - to prevent person to person transmission & keep things sanitary.
For many this means raising to/near slam level after soaking anyway so there’s plenty left the next day & possibly get them through the next soak w/ out going below minimum.
If u do all these things & cc’s become consistently 1 or above it’s time to purge & begin again. This may happen sooner than later. The next round of purging should clear out anything still lingering.

 

[Tembroke]

Ah, I see. So if a few cherry blossom petals were floating around, or a small piece of moss fell in and sank to the bottom, or a pine needle was in the filter compartment… that could give me 0.5CC?

There was a windstorm yesterday, and quite a few cherry blossom petals fell in while we were using the tub. I caught most of them, but some of them were behind the headrests, some clung to the cover and fell in when the cover was put back on, etc. So maybe that’s part of what was going on.

We also have a kick board that floats around like a life raft, holding the 8 rubber duckies and two decks of waterproof cards… but a foam kick board probably isn’t oxidizing, because it’s designed to withstand use in chlorinated water, right?

I have a SWG, so it’s easy to keep the FC level up in between uses. My one concern is that a high FC level might deteriorate the cover and headrests faster… so I’m trying to trade off: electricity costs (from cover being open to let the chlorine off-gas), cover replacement costs (from high sustained FC), cost and time of water changes (if lower FC leads to higher CC sooner), and water quality/comfort (less pleasant with higher CC or really high FC).