Keep losing chlorine in Spa?

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RichTJ99 said:
Thanks for the help, so its a slow process - not a quick one.

So if I am aiming to go from 0 to 10, then I use .8 oz which is not quite 2 tablespoons of dichlor.

I will add that tonight & see how the FC goes over the next few days, then slowly add more dichlor.

Should I stay out of the tub for a few hours after adding it?
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JVTrain said:
You can hop in the tub as soon as the dichlor is dissolved, provided your FC is not over 10 ppm and your pH is between 7.2 and 8.0.
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Joel beat me to it but I would add this bit of caution - it depends on your chlorine tolerance.

Even with 80ppm CYA in my spa, I hate sitting in the hot chlorinated water if the FC is much over 2ppm (in fact, I actually chemically lower my FC prior to getting in when I use my attached spa). Other people seem to tolerate higher FC with no issues at all. So I would follow Joel's recommended levels but with the awareness that you may find the water uncomfortable. If that is the case, then I would wait for the FC to be low before soaking. Some people let their spa's FC get low, soak in the tub and then bump the FC up higher than typically recommended in between soaks. I'd likely be someone that follows that route if I owned a hot tub.
 
RichTJ99 said:
Do i have this backwards? Dichlor is used to increase FC but also will increase CYA as a "side effect"? I thought Dichlor was for increasing CYA.
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Dichlor is stabilized chlorine. It adds both FC and CYA to water. If you wanted to increase CYA independent of FC, then you can buy granular pool "stabilizer" which is (or should be) 99.9% cyanuric acid.

Trichlor is another form of stabilized chlorine that adds CYA. It adds only 6ppm CYA for every 10ppm FC BUT it is much more acidic than dichlor and can not be used in a spa because the tablets dissolve too quickly.

Calcium hypochlorite is stabilized chlorine and it adds calcium hardness to the water as well as FC BUT it is fairly caustic and will raise pH. It is also not suitable for use in a spa.

Bleach is sodium hypochlorite and it adds FC and salt to the water. Regular, 8.25% laundry bleach will add about 1.6ppm salt for every 1ppm FC.
 
So I added two tablespoons of Dichlor, waited about 5 minutes & tested the water - not really any change so i will wait an hour or so while the spa is running to see if the ph comes down at all.

Whats the typical wait time for testing purposes?
 
So i ended up adding 3 tablespoons last night & this morning while the chlorine is extremely high, the PH seems to have lowered, at least a little. I will wait another day or so and add another tablespoon to see where we are at.

On the other hand the CYA test from the TFP tester, To confirm I am doing this correctly.

1. Fill pool water in bottle until bottom of the label
2. Fill the larger bottle (dont have it in front of me) to the top of the label.
3. Shake
4. Start pouring mixed chemicals into long beaker with black dot
5. At some point while looking straight down the black dot should disappear?

My black dot is always clearly visible - am i doing the CYA test right?
 
3 tablespoons of dichlor in a 600 gallon spa is only 10ppm FC and 9ppm CYA. If your spa started off with 0 CYA, then it is 9ppm now. You can not measure 9ppm CYA. 20ppm is the absolute lowest possible detection limit of CYA because the test uses melamine to form melamine cyanurate particulates (that is what generates the turbidity) and that reaction has a solubility limit of 20ppm. So with low CYA, the best you'll get is a little bit of hazy water but not enough to do the test. This is why TFP does not recommend doing the test below 30ppm because it's next to impossible to get accurate results.

You now have about 10ppm CYA in your water so you should find that the FC demand is a little lower. Once you get closer to goal of 30ppm CYA, your FC loss rate should go down.
 
How high are your chlorine levels?

Anything over 10ppm FC and I'd wait for the FC to drop before adding anymore dichlor. You're basically superchlorinating (shocking) the water every time you add large doses of dichlor and that's eventually going to be hard on the hot tub surfaces. Most people add dichlor slowly over weeks of time to build up the CYA levels.


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So i am back in town again. I had been using the Dichlor only for the last week or two. PH came down, chlorine was at a good level. I keep finding that the levels of chlorine seem to go to 0.

So I guess I am ready to give the 'ahh some' product a try. Only question I have is how exactly to use it. I get that I add an amount based on water levels, run the product, then empty the tub & clean it out (not sure what I clean it out with beyond papertowels). Then fill it & start over.

Dont you end up with residue in the tub? Do you fill/empty it twice?
 

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If you can, rinse it down with a garden hose a little while it is draining. Wipe down the walls. Some people will take their shop vacs and suction out the jets or use an air compressor to blow out the lines a little. It all depends on what tools you have available. If water isn't too expensive, a second water-only run and flush is a good idea too but not necessary.

Once you start it all back up, if there is any debris from the plumbing flush, the filter will capture it and the chlorine you add will destroy anything left over.


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So I have been using about a tablespoon a day of the dichlor & no liquid chlorine for about 10 days. I didnt do any test beyond the chlorine / ph test. The PH seems perfect now. I am a little surprised that the dichlor granuals are 'used' so quickly in the hot tub but it is at 102F 24/7. I guess the heat uses the chlorine quicker?

Is there a downside of using dichlor vs liquid chlorine?

I would love to figure out a way to get the chlorine to last more than 24 hours as when i head out of town on a 1 week vacation I am not sure what to do.

Thanks,
Rich
 
Dichlor adds both chlorine and CYA to your water. CYA is a buffer for chlorine, meaning it lowers the overall concentration of active chlorine and holds the rest of the chlorine in reserve. The higher the concentration of CYA in your water, the lower the level of active chlorine. Once active chlorine levels drop too low, the rate of kill of pathogens (bacteria and viruses) drops drastically and the tub will no longer be sanitary. It is also possible to get algae in the tub too. SO over-use of dichlor will lead to a less sanitary tub.

Once you build up a CYA level of 30ppm, you can switch to liquid chlorine (bleach) and it should act very similar to what you are seeing now with the dichlor. To conserve chlorine, you might consider dropping the stand-by temperature of the tub down to 90F or 95F. Chlorine reaction rates (including self-oxidation) roughly double with every 13F increase in temperature. So, lowering the standby temperature when no one is soaking in the tub can help to conserve chlorine.

Unfortunately, there's no getting away form daily or every-other-day additions of chlorine in a hot tub. That's just how it is. If your tub is compatible with salt water, some folks on here using drop-in salt water chlorine generators to automate the production of chlorine. That can make it very convenient.
 
Hi

So i have had a much easier time keeping the chlorine levels up using one of those floating dispensers - PH has been perfect also. I did all my tests & have the following results:

FC - 7.5 ppm
PH - 7.5 ppm
CC - 2 ppm
CH - 125ppm
TA - 130
CYA - 80

I think the TA & CYA are higher than they should be. I am using a combo of things.

The 1" chlorine tablets in the floater.
Liquid chlroine periodically
Dichlor - once a week (or twice if the chlorine goes too low).


Is there anything with my numbers that should keep me out of the tub?

Thanks,
Rich
 
The problem with stabilized chlorine in a hot tub is two fold -

1. Trichlor and dichlor are both very acidic and dissolve very quickly in a hot tub. This will cause the pH to lower rapidly and the FC to increase very quickly. Overuse can cause the TA to crash leaving very acidic water conditions that can damage the tubs components

2. Excess CYA in a tub is just as bad as excess CYA in a pool - it reduces the effectiveness of the chlorine requiring you to maintain ever increasing FC levels in order to maintain appropriate pathogen kill times. Eventually CYA build up will require draining.

If you want to use a tablet floater in a tub, then it's probably better to switch to bromine as that will be less affected by DMH levels and the pH and TA will be easier to manage.


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Hi,

So a week later I have the following:
FC - 3
CC 4
TA -13
CYA 80


I am thinking I am going to drain the tub this week. The CYA is very high & isnt going down. Are my levels (chlorine is low today) aside from CYA OK? I am traveling at the end of hte month so I am going to try to stick with chlorine until I get back. I was planning to have friend stop by to swap chlorine floaters.

I am noticing that the PH is lower & i am adding borax every few days.

So to confirm CYA levels dont just go down.

Would an OK solution be to drain half the tub & put new water in the tub vs draining the whole thing?
 
OK - i did some additional reading & am in the process of changing out a good chunk of water today.

So Trichlor (or the small chlroine pucks) release chlorine and acid. Dichlor does the same but more acid.

If i keep a permanant floating dispense in the tub my CYA will always be going up since the chemcials are chlroine and CYA.

CYA doesnt go down unless you change the water.

It sounds like my options are:

1. Use LC every day as it will dissipate in the water
2. Use LC daily & put the floater in if i am on vacation
3. Get a LC dispenser?

4. Switch to bromine which will handle a floater
a. Involves learning how to use bromine (smaller user base?)
b. Must empty tub completely

Is that about right?

Thanks,
Rich
 

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