I Can't keep chlorine in the hot tub

[Kev north]

 I add chlorine and by the next morning   I do a test and it's zero again
 My Ph  is okay
 cai've only had the hot tub two weeks
 Can anyone help

[Tman122]

I add chlorine and by the next morning   I do a test and it's zero again
 My Ph  is okay
 cai've only had the hot tub two weeks
 Can anyone help

Sounds like your doing it right to me. Chlorine dissipates quickly in hot water. The idea is to kill the nasties when you add it after your soak and have the level below 1ppm for your next soak. Then repeat. Add more to learn how long it takes to dissipate before your next soak.

Most people don't like soaking in a hotel tub when they own their own because public hot tubs are required to keep the chlorine level constant through an automatic feed system. Hence the chlorine smell.

[Kev north]

 Thanks for your help   I can relax now 

[someguy]

This is a very common issue in hot tubs that may have Biofilm build-up in the plumbing and jets.
Biofilm and other organic contaminants gain a foothold deep inside the plumbing and your sanitizer is used up trying to kill and remove it.  Scientific evidence suggests that high sanitizer levels are not capable of penetrating and removing this build-up but they keep trying. You need to use a purge or flush product designed to help penetrate and disrupt the bio-accumulation.  Easy to do.  You MUST drain the water after performing this step.  Most people find that their sanitizer demand lessens after this is done. Plus, your water will feel, smell and look better than ever.

[bud16415]

I add chlorine and by the next morning   I do a test and it's zero again
 My Ph  is okay
 cai've only had the hot tub two weeks
 Can anyone help

You didn’t mention if your tub is brand new or new to you for just two weeks. If your tub is new I seriously doubt you have a biofilm build up in your plumbing. If you bought a used tub or moved into a new house that came with a tub then I would suggest because everything is new and unknown how it was maintained to take the time and possibly use one of the purge products to clean it out first thing.

You also didn’t mention what type of chlorine (sanitizer) you are using or how much, and you also didn’t mention how big the tub is or how heavy the bather load is. Chlorine made for pools is not what you want to use in a hot tub. They are made for cool water and will break down too fast in the hot water. Did a dealer or anyone give you a program to follow as to what to do? If so what did they tell you?

Tman122 is correct you would like your level low when you get in but you also don’t want it falling to zero.   

[Vinny]

Are you putting enough chlorine in where it's 3 PPM at 20 minutes after you add it? You shouldn't add "some" you need to have amounts so you know how much to add. My tub usually has a residue amount 24 hours later so I'm confident the tub is santized, you should be shooting for some chlorine in the morning.

[The Wizard of Spas]

Are you putting enough chlorine in where it's 3 PPM at 20 minutes after you add it? You shouldn't add "some" you need to have amounts so you know how much to add. My tub usually has a residue amount 24 hours later so I'm confident the tub is santized, you should be shooting for some chlorine in the morning.

This is perfect.  And to expand upon this:  9 of 10 new hot tub owners that I deal with always have too little sanitizer when they first get the tub.  Don't be shy about adding sanitizer as you can always use it back up.  Once you get your bearings it'll just be like cooking: 

When you first read and cook using a recipe you're measuring everything exactly, using timers, and doing the exact process that the directions call for.

When you've cooked this recipe 10, 20 times, you're kinda eyeballing stuff, and knowing "eh, it's been in the oven long enough" and going from there. 

The former is where you are, the latter is where you'll be.  Make sense?

[wmccall]

Thanks for your help   I can relax now 

We really need to know how big your hot tub is, how many gallons, and how much chlorine you are adding.   Ideally as someone said, if its down to zero the next day when  you get in no problem. However, if you skip a couple of days, then you might have a problem. 

[dlleno]

I did some experimenting with my own tub back when I was fighting sanitizer levels, and would offer a couple of conclusions I made for myself

1.  I personally am a bit cautious when it comes to zero sanitizer level.  personally, I found that if chlorine does go to zero over night, then its time to do a mild shock and measure the no-load sanitizer decay rate, which is a good indicator of water health.  I would only hasten to add that  zero chlorine doesn't mean there is a problem;  it just means there is nothing there to prevent one.  Yes, I too have recovered many times from zero chlorine levels;  I just find that when this happens I need to re-assess my water health and, more often than not, shock (and here I mean shock as in 10ppm chlorine, not a full on decon procedure that requires 50 or even 100ppm)

2.  The sanitizer decay rate test  is a very effective and easy way to measure water health.  The idea is to pick a time when you believe your water is healthy, stable, and has no load (for example, the day following use).  Then, raise the sanitizer level to some figure (like 4ppm chlorine) that you can measure accurately.  keep the spa covered and heated.  Measure chlorine again at 24 hours -- you should see at least 75% of the original level or  3ppm if you started with 4ppm (this is 25% decay).    If you have less than 75% of your original chlorine level, then something nefarious has been consuming it, and you need to find out what that is.   It could be something "innocent"  --  for example a critter that crawled inside, dust and wind, tree pollen,  etc.  But if none of those things have happened, then your water is not healthy. 

I went through several thousands of gallons of water to learn this, but basically when I encountered sanitizer decay rates greater than 25%, something was wrong, and  I had to purge and drain in order to solve the problem.  now, with healthy water and a strong corona discharge ozone generator, I can maintain .5ppm bromine for several days without any floater or other manual or automatic means of adding sanitizer. 

note that the 25% decay figure assumes no ozone   

[dlleno]

You didn’t mention if your tub is brand new or new to you for just two weeks. If your tub is new I seriously doubt you have a biofilm build up in your plumbing.

I suspect you are right in may situations;   would just add just a little more caution here, as it is entirely possible (and it happened in my case) for a new tub to be biofim contaminated.  in order for this to happen, a few conditions must be present, but when you look over the list you will find that these conditions are pretty common.  note that many new spas are subject to the following conditions:

1.  wet tested (yes with chlorine, who's protection ceases as soon as the water drains)
2.  stored in a warehouse
3. transported or stored on a truck


add warm temperatures to the above and you have a recipe for biofilms. 

My most recent purchase (hot springs grandee) came from the factory, road in a truck, sat at the store, and sat on my patio before initial startup.  from the very first fill I had sanitizer consumption problems that I did not solve even with a 50ppm decon procedure.  not until I purged did I fix the biofilm dudes that were lurking in my pipes at first delivery