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Chlorine levels hot tub


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Hi All,

I own a brand new Calspas hot tub which I am very proud of. I have never owned a hot tub before in my life so of course I want to keep it pristine as long as I can. One thing I do religiously is testing the water chemistry every single morning after I wake up. My local spa vendor told me to test once every week if its not being used or every few days if the tub is being used by people. However, I like to do it daily.

Newbie question here: I know I have to maintain a chlorine level of 1 - 3 ppm at all times. However, for whatever reason every morning I come in with my test strip, there's almost no free  chlorine left in the water, even when I haven't used the tub in a week for example. Is this normal? Why does the free chlorine disappear out of the water so quickly even when the hot tub is not being used? It confuses me even more because my spa vendor told me that if nobody uses the tub I can test and adjust the water chemistry once a week, but it seems I need to add chlorine literally every single day. pH, alkalinity and hardness are all in the OK zones and stable. I rarely have to adjust these levels. I just need to add chlorine daily. The hot tub is sitting indoors in an enclosed gazebo and also has a cover over top.

Thanks for the insights in advance.

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I would be interested in this as I see the same thing, though now with a Frog chlorine cartridge , it seems to be happening less. 
However, since switching from bromine to chlorine , I notice my pH dropping much lower! 

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Few things to consider.....

  • New hottubs are filthy things from factory assembly and testing (the water used in testing is often reused in the factory for a week or more before they change it - just imagine what's floating around in THAT water lol).  Lots of nasty stuff festers in the plumbing between assembly and delivery days.   Pretty much every new hottub needs a ton of extra sanitizer to fully clean the inside of the spa.
  • Biofilm and other nasty contaminates and eat up your excess free chlorine very fast.  This goes back to the first point I mentioned.  Currently, you may not be using enough chlorine to maintain your spa.
  • Does your hottub have an Ozonator unit?  Ozone burns off organic contaminants through oxidation (like shock) but is such a strong oxidizer that it even reacts with free chlorine. This means you can shock after use and not have to soak in a bleach bath the next day, because the ozone will burn off all the chloramines and most of the chlorine overnight.    Some brands tie the ozonator to a circulation pump running 24/7 which is more effective than many budget brands who toss in an ozonator and pair it to run with the filter cycle twice a day (ozone doesn't build up in the water, so its only effective while being injected into the water)
  • Water chemistry woes are a problem for basically everyone with a new hottub.  Even the glues used in construction are acidic and will pull the pH down over time until they fully neutralize internally.  Plan on draining/refilling after 1-3 months and I promise your water chemistry will be MUCH easier   (note, many of us like to use a purge cleaner like AhhSome to extensively clean the internal plumbing before every drain/refill.  I suggest looking into it).

 

10 hours ago, Scryden said:

My local spa vendor told me to test once every week if its not being used or every few days if the tub is being used by people.

There are a dozen different ways to care and maintain your water.  My dealer's care routine has me dosing the spa after each use with granular chlorine, and testing the pH once a month when I clean the filters and the cover.  But my care routine is not compatible with every spa on the market

My advice is to be careful taking advice from strangers on the internet, especially while you're still new and learning how to care for your spa.   Water borne illnesses are no joke, you do NOT want to deal with Pseudomonas folliculitis (Hottub Rash).   Your local CalSpa dealer should have knowledge of your hottub's configuration and your local water source - I would consult with them and take their advice for water care until you know what you're doing. 

(And by the same token, know that pool chemical supply dealers are in the business of selling chemicals.  I would be careful taking a water sample to a pool chemical supply store for advice as I guarantee they'll sell you a bunch of chemicals you don't necessarily need)

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Thanks Ratchett!

 

12 hours ago, ratchett said:

Few things to consider.....

  • Does your hottub have an Ozonator unit?  Ozone burns off organic contaminants through oxidation (like shock) but is such a strong oxidizer that it even reacts with free chlorine. This means you can shock after use and not have to soak in a bleach bath the next day, because the ozone will burn off all the chloramines and most of the chlorine overnight.    Some brands tie the ozonator to a circulation pump running 24/7 which is more effective than many budget brands who toss in an ozonator and pair it to run with the filter cycle twice a day (ozone doesn't build up in the water, so its only effective while being injected into the water)

Yes, it has an ozonator. Right now it runs for 6 hours a day divided in two 3 hour filter cycles. However my tub is also "polling" the water temperature every 30 minutes and runs the pumps including the ozonator when the water needs to be heated. It wont run 24/7, but filter cycles + water heating it probably runs 8 - 10 hours a day.

The only way the ozonator comes on is when my pump #1 is activated and it automatically switches back off on its own if its not in a filter cycle and the water does not have to be heated. The only way for me to have the ozonator run 24/7 is if I modify my filter cycle to run 24/7 instead of 2x 3 hours a day. Is that what I should do?

Quote
  • Water chemistry woes are a problem for basically everyone with a new hottub.  Even the glues used in construction are acidic and will pull the pH down over time until they fully neutralize internally.  Plan on draining/refilling after 1-3 months and I promise your water chemistry will be MUCH easier   (note, many of us like to use a purge cleaner like AhhSome to extensively clean the internal plumbing before every drain/refill.  I suggest looking into it).

For me this is going to be a problem. I live in Alberta Canada and we get 8 months of winter and freezing cold a year. My first fillup was done on September 25. So the water is only 2 weeks old. If I wait 3 months its already going to be in the freezing temperatures and then I wont be able to drain and refill it as the water will instantly freeze and my water line in the yard will also be frozen. Again, this is something I asked my local Spa dealer about and they told me I have one of the more higher end hot tubs with advanced filtering, ozonator etc so the water should last till Spring so I dont have to worry about draining and refilling it in the blistering cold. Or so they said at least...

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Hello Scryden: Your vanishing free chlorine situation points to exactly what ratchet said.  Your tub has biofilm issues.  Every single brand new hot tub sold today needs their plumbing purged to remove the slime-forming microorganisms.  In addition to purging a new tub it is imperative that you perform this plumbing colonoscopy on a regular basis, usually every 6 months.  Small gallon hot tubs neeed to have this done every 4 months. 
Swim Spas can go 12 months.  Free chlorine decay rates is the red flag. 
We have some dealers, one in particular in Victoria, BC, who purges every single hot tub upon delivery.  He thoroughly explains why they do this and proceeds to educate the new owner about testing and maintaining healthy water.  Unfortunately, very few dealers will take the time to do this important first purge before use.  You need to do this.  You will definitely see dramatic changes in your free chlorine readings.  Performing regular plumbing colonoscopies is the single most important maintenance protocol you can do to ensure you soak in crystal clear and healthy hot tub water.

All it takes is for a new user to get hot tub rash from Pseudomonas Aeruginosa biofilm bacteria or something far worse, and they become believers.  Why won't manufacturers and dealers just tell consumers the facts?  Scryden:  Do the community a huge favor.  Purge your hot tub with an effective plumbing cleaner soon.  Remember, all plumbing cleaners are not of equal potency.  Get one that works.  Then, report back to the forum regarding your free chlorine decay rate.  The community is trying to help you out so you can help all those new hot tub owners coming behind you.

 

 

 

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18 hours ago, Scryden said:

Yes, it has an ozonator. Right now it runs for 6 hours a day divided in two 3 hour filter cycles. However my tub is also "polling" the water temperature every 30 minutes and runs the pumps including the ozonator when the water needs to be heated. It wont run 24/7, but filter cycles + water heating it probably runs 8 - 10 hours a day.

The only way the ozonator comes on is when my pump #1 is activated and it automatically switches back off on its own if its not in a filter cycle and the water does not have to be heated

Boom, we found out what's happening to the chlorine   🙂

 

18 hours ago, Scryden said:

The only way for me to have the ozonator run 24/7 is if I modify my filter cycle to run 24/7 instead of 2x 3 hours a day. Is that what I should do?

I would not set your filter cycle to run 24/7.   Maybe consider adding a circulation pump to your tub, but I wouldn't bother with all that. Just leave things how they are set up, talk to your dealer and see what they advise for filter cycles and such.

 

18 hours ago, Scryden said:

For me this is going to be a problem. I live in Alberta Canada and we get 8 months of winter and freezing cold a year. My first fillup was done on September 25. So the water is only 2 weeks old. If I wait 3 months its already going to be in the freezing temperatures and then I wont be able to drain and refill it as the water will instantly freeze and my water line in the yard will also be frozen. Again, this is something I asked my local Spa dealer about and they told me I have one of the more higher end hot tubs with advanced filtering, ozonator etc so the water should last till Spring so I dont have to worry about draining and refilling it in the blistering cold. Or so they said at least...

Yeah, I figured that would be the case.   And your dealer is correct in most cases your system should help reduce the amount of water changes you need to make in the future.... once things are fully clean/balanced/sanitized in your tub. However this is still a new spa, you will likely bang your head against the wall multiple times trying to get water chemistry in line. 

If you have a warm spell for a few days within the next 1-2 weeks, it might be worth draining and refilling before the cold winter season. You don't need to wait a full 2-3 months before your first water refill.

Not saying you are absolutely required to do this, but just saying if you don't you'll likely end up dumping a ton of chemicals in your water to keep things balanced/sanitized over the next few months ending up with a nasty soup of chemicals including those pulled out of the plumbing as things neutralize and balance internally.    You can do this, but just know this won't be normal and isn't needed once things are fully balanced/sanitized internally and filled with fresh clean water.

Just my $0.02

 

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Thanks guys. Really appreciate the help. If we get another warmer day soon I will purge, drain and refill the tub. My spa dealer gave me a starter kit full of chemical products from the brand Spa Life. One of the bottles is "Whirlpool and Tub Rinse" See here. It says it cleans the plumbing system. Do you have any experience with this product and can you say if its good? To apply it I just add it to the water, let it run for an hour or so with the jets on and then drain the tub?

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5 hours ago, Scryden said:

One of the bottles is "Whirlpool and Tub Rinse" See here. It says it cleans the plumbing system. Do you have any experience with this product and can you say if its good?

That sounds like a purge cleaner, but purges aren't all created equal.  This blogger took to the task of testing a few different leading purge products to see how they stack up (essentially he used the scientific method to test each cleaner head to head - the theory being that if the one product is effective, a subsequent purge with a different product should release no additional biofilm).  You can read up on his results here   - https://rvdoug.com/hot-tub-maintenance/

5 hours ago, Scryden said:

To apply it I just add it to the water, let it run for an hour or so with the jets on and then drain the tub?

That generally sounds like the idea.  Check your pH and chlorine levels.  I usually add a bit of extra chlorine before purging to ensure things are working. 

When I purge, I run the jets for a while, then turn off the jets and clean any scum at the water level before it has a chance to harden.  Then I would run the jets again for a while, clean the water line again.  Repeat several times until almost nothing new comes out of the plumbing, then drain and refill.  But I'm OCD about keeping my spa clean (to the point where I literally invented a powertool to turbocharge my filter cleaning routine.... still beta-testing the design, not available for sale yet lol).

 

 

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I have tried different purge products. I didn't get much out from Ahh-Some, but it may be that during the preceding period , those guests in my vacation rental were very clean. I did get a lot out with Silk Balance Clean Start, but again,  maybe that time the guests were exceptionally dirty!

 

Does anyone leave it in overnight or just 30-60 minutes?

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Ideally, you perform the purge with the filters removed and run the jets for 30 minutes after adding the cleaner.  Be sure to wipe any of the released sticky gunk so it doesn't dry and adhere to the hot tub shell.  This is very important.  Silk Balance is a decent cleaner and I believe that they recommend a 30 minute purge time.

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14 hours ago, Susanj said:

I didn't get much out from Ahh-Some, but it may be that during the preceding period

First time I purged, I made the mistake of not testing chlorine first (ozonator had burned off almost all FC prior to my first time purging).   Now I always add a bit of extra chlorine 30 minutes before I start to purge. 

Additionally, unlike the instructions, I dilute the gel in a cup of hot water before adding to the tub.  Then I run my jets for 20 minutes, then turn off for 10 while cleaning the scum.  Run jets for another 20, then off for 10.  Repeat 4-5x times in a row until nothing new comes out of plumbing, and then I drain the spa.  You'll be surprised how much comes out on the second and third jet cycles

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Thank you for that information.  We are very much aware of the "hanging chads" so to speak.   Most times the purge gets the low hanging fruit of bio-gunk on the first cycle.  Letting it set for a few minutes and turning on the pump intermittently will usually cause enough water flow propulsion to knock loose Biofilms that were still hanging on for dear life.  Very good information you have shared.

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So I started to notice a trend with my water every time after I add chlorine granules. The water chemistry is still balanced and water super clear, but I every time I add new chlorine and let the jets run for about 20 minutes, I come back and see this on top of my water: 20211015_215815.thumb.jpg.555dee0f692b09669464e7c7e85c3d20.jpg20211015_215926.thumb.jpg.c97aaba10c844bf9d23a47b2b0ec7a7e.jpg

 

The camera doesnt really do a good job at capturing it because it looks like little flakes in the pictures but its not. Its more like clusters of little air bubbles clumped together and it makes the surface of the water look a bit hazey. But after a couple of hours its all gone and clear again. Is this a normal thing? Or is it a sign that I am adding too much chlorine?

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