Chlorine smell after shocking

[jbequer]

Is it normal to smell chlorine 5 hours after shocking to 10ppm? I normally shock once per week, but this is the first time I smelled the chlorine so strong.

[chem geek]

Did you leave the spa uncovered for some time after you added the chlorine?  If not, then the smelly chloramines that formed and are volatile probably didn't get a chance to escape.  They should be easily removed by uncovering the spa and running the circulation or jets for a short time.

[jbequer]

I left the cover off for about an hour or so. How long is it long enough for the cover to be off?

[chem geek]

Usually that's enough.  You may have had more organics than usual.  Or perhaps you've been using Dichlor for so long that the CYA has built up and slowed down chlorine's oxidation of bather load too much.  Do you use Dichlor-only and if so when did you last change your water and what is your bather load (how many people, how many hours, how many days/week) and size of spa in gallons?

[jbequer]

I use Dichlor, two bathers two times a week for about 45 min and the last time I changed the water was 6 weeks ago. I use two tbs after each use and shock once a week.

[chem geek]

Two bathers for 45 minutes is 1.5 person-hours which with no ozonator (do you have an ozonator?) would need 5-1/4 teaspoons of Dichlor which is almost 2 tablespoons which is what you are doing.  This bather load twice a week would build up 115 ppm CYA over 6 weeks if I assume a 350 gallon spa.

From a Water Replacement Interval (WRI) perspective, WRI = (1/9) x (Spa Size in Gallons) / (# of person-hours per day) = (1/9) x (350) / (1.5*2/7) = 90 days.

The above doesn't count the "shock" you are adding.  I presume that's non-chlorine shock, but if it's more Dichlor, then that would raise the CYA level even more.  So it's plausible that you are just getting the CYA too high to handle the bather waste quickly enough though usually you see this sort of thing at even higher CYA.

This sort of problem is one reason some people use the Dichlor-then-bleach method, but it's more complicated because you have to adjust TA lower and use 50 ppm Borates to keep the pH from rising too quickly.

[Vinny]

The chlorine smell is chloramines which is the combined chlorine. There are 2 ways to break it one is with a very high dose of chlorine but you need to know how much combined chlorine you have and the second is by using non chlorine shock (10 years ago it was called MPS) .

Based on your usage and what chem geek posted you might want to just drain and refill and get fresh water in there and start a new cycle.

[jbequer]

Thank you Chem Geek and Vinny, you guys have really helped me out a lot on this forum.. I am very thankful to both of you !! You have definitely both made my hot tub ownership enjoyable, i don't know what i would do without your great advice, thanks a million !!!

I just don't understand why the water went bad so soon, if this is the case ?? This morning when I opened the cover, I smelled an initial chlorine smell but after about 10 sec no longer smelled it?? The water is very clear, just a little bit of foam when all jets are on, but not anything excessive.

I don't use an ozinator , I use Dichlor as shock and its 376 gallons. I normally use 2 to 3 Tbs for shock to get 10 ppm. As far as the foam, I'm not sure if it's foam or bubbles created by air. When I turn the jets off, they go away almost immediately. I have been using Spa Perfect Enzyme once a week, along with Aquafinesse. The water is silky smooth, absolutely no film or scum problems..

So my question is, is it still ok to use 1 or 2 more times before changing the water? Of course with sanitation in mind.
The reason I ask,  is because I have relatives staying for Thanksgiving that will most likely want to use the spa. I was planning on changing the water after they leave.

On a side note, last week i took my water to Leslies Pool Supply to test.. The results were all within good range . My TDS was not anything significant.

Is it not just the Shock of the Dichlor smell that i am smelling ? Maybe not leaving the cover off long enough ? Its just hard to believe that the water went bad this soon, since i haven't done anything out of the ordinary as far as bather load ??

Checked Chlorine, still 10ppm after 30 hrs, why is not going down ? I thought by know it would be lower, so i left it running with cover off full out
with cover off.

[Vinny]

You're welcome!

I know for me I thought hot tub water care was going to be easy because I owned a pool first - I was completely wrong.

Your water hasn't gone bad, it just has chloramines in it. Here is a scenario ... You soak and you add chlorine, it gets used up and turns into combined chlorine (cc) which are chloramines. Originally it was say 0.3 ppm butyou soak again and add more chlorine, now depending on how much you put in it may eat up the cc or it may not. If we assume that it didn't now you have to add the amount of this soak to the last soak and hopefully the next time you add enough to break the cc (typically about 10 x the cc amount). Carry it a little further, you went in sweaty or had body lotions on a couple times during the week and the chlorine had to work extra hard to eat that up so the cc was high for those days ... After a week your cc level may be close to or over 1 so in order to break that cc you need at least 10 x whatever number is and if you didn't achieve it you're starting at that level for the next week. If you get that high enough you get the smell. Non chlorine shock will break the cc as well.

As far as high chlorine, I get that every so often and I refer to it as chlorine lock. My tub will keep a high chlorine sometimes for a week ... At least nothing is growing. I've soaked in the tub with high chlorine, not a big deal to me. Also, based in you high stabilizer it is kind of neutralizing the corrosive effects of the chlorine.

As far as water change, I definitely would wait until after Thanksgiving and all those bodies in that water. Be prepared for possible cloudy water, water not acting right and high chlorine demand.

[jbequer]

Thank you for your advice..
Isn't it normal to smell chlorine if the level is 10ppm ?

[Vinny]

I guess the question is how strong is the smell? Some smell, yes. A lot of smell no. I sometimes get a light smell but it disapates after a few minutes, if it doesn't or its a heavy smell I break out the non chlorine shock. I have a bad sniffer so its possible that there is a smell and can't smell it until it gets stronger. If I want to measure cc then I wait until my free chlorine is 0 abnd look to see how high the cc is.

[jbequer]

Is 10ppm overkill? Maybe I need to cut back to 6ppm for a shock ??
What do you guys recommend?

[Vinny]

If you are just adding more chlorine to give the killing power a boost then 10 ppm may be high. If you are trying to get breakpoint chlorination (the point where combined chlorine gets burnt up) it may be too low. Generally you need about 10x the combined chlorine amount to get it to disappear.

I don't use chlorine to burn the combined chlorine often but do use it for additional killing power. I keep non chlorine shock on hand to do the burning up of the combined chlorine. I will say that whenever I use it whatever chlorine smell goes away. I will dose to 3 ppm most times but will add another 3-5 ppm every so often "just in case" something is growing. As I do that if my combined chlorine is say 0.5 ppm then having 6-8 ppm free chlorine will burn it up along with having a higher dose of chlorine if something needs to be killed with that extra dose.

[chem geek]

If you don't have a Taylor K-2006 test kit, you should get one.  And you should then test your Cyanuric Acid (CYA) level.  I think you'll be surprised at how high it is.  For every 10 ppm Free Chlorine (FC) added by Dichlor, it also increases Cyanuric Acid (CYA) by 9 ppm.  Most of the FC in your spa is bound to CYA and not effective so if the CYA gets higher then your active chlorine gets level.  That means that bather waste will build up and you can also build up chloramines because the active chlorine level is too low.  It's not just the smell, but the water will tend to turn more dull over time because the active chlorine level drops due to the CYA buildup.  This is most especially noticeable in spas with no ozonator since there is no ozone to oxidize these built-up chemicals.  This is why the Dichlor-then-bleach method can double the time between water changes -- because it switches to bleach once the CYA has built up so keeps the active chlorine level fairly constant after that point.

[Vinny]

What chem geek said is true although many people do use just dichlor and are fine but the symptoms of dull water is there.

I do use bleach in both my pool and tub although in a new tub you may void a warranty because you aren't use a spa chlorine.

My only gripe with bleach is it's not convenient in the winter. IMO it is much easier to throw 2 or 3 spoonfuls then to measure 3 oz bleach in the winter. Of course premeasuring the bleach before you go out is something that can be done.