Chlorine Keeps Dissappearing?

[JimKW]

I have this 2005 Sundance Optima for about four months now. When I got it I filled it and was fine by just adding about 1/4 to 1/2 oz of Chlorine with Dichlor after each use or about every 3rd day if we weren't using the tub regularly. Well about a week ago the water got real cloudy and the chorine level was low. So I changed the water. I noticed the heater was leaking a little so I put a new heater and a new filter on it with the water change. I put about 2-3 oz of the Dichlor in when I filled it and the the chlorine level was pretty high at first. I also had to add something to raise the Calcium Hardness. It was at 75 and I raised it to 175. Now my chlorine level keeps going back to none. I added about 1/4 oz last night and it was right where it is supposed to be. 3 hours later it was low and this morning gone. I put a full ounce in this morning and will check it again when I get home tonight.

[waterbear]

I have this 2005 Sundance Optima for about four months now. When I got it I filled it and was fine by just adding about 1/4 to 1/2 oz of Chlorine with Dichlor after each use or about every 3rd day if we weren't using the tub regularly. Well about a week ago the water got real cloudy and the chorine level was low. So I changed the water. I noticed the heater was leaking a little so I put a new heater and a new filter on it with the water change. I put about 2-3 oz of the Dichlor in when I filled it and the the chlorine level was pretty high at first. I also had to add something to raise the Calcium Hardness. It was at 75 and I raised it to 175. Now my chlorine level keeps going back to none. I added about 1/4 oz last night and it was right where it is supposed to be. 3 hours later it was low and this morning gone. I put a full ounce in this morning and will check it again when I get home tonight.

Please post a full set of test results not done with strips and in the meantime shock the spa with an unstabilzied chlorine source such as cal hypo or bleach to 15 ppm and wait for the FC to drop below 10 before entering the spa.

[JimKW]

Please post a full set of test results not done with strips and in the meantime shock the spa with an unstabilzied chlorine source such as cal hypo or bleach to 15 ppm and wait for the FC to drop below 10 before entering the spa.

My current water readings are as follows:

- Free Chlorine: 1.5 ppm

- Combined Chlorine .5 ppm

- Total Chlorine: 2.0 ppm

- pH: 7.5

- Hardness: 200 ppm

- Alkalinity: 100 ppm

- CYA: ~50 ppm

That is after putting in 1+ oz of chlorine this morning which should have had my level sky high. Especially since I put in 1/2 oz last night.

Oh yea and we have not been using the spa at all and the cover has been on. The guy at the place where I buy my stuff said it's not uncommon to lose chlorine right after a refill and to just keep putting it in and to not let it get down to zero. So I just put another 1/2 oz in. He said it should stablize and get back to where it was before.

[PaulR]

Stop using the dichlor. It adds CYA as well as FC, and your CYA is already high enough for an uncovered pool; really high for a covered spa. Use bleach instead.

See: Dichlor/bleach method in a nutshell

--paulr

[gman]

Just curious... but how long after you add your chlorine do you test your FC?

gman

[JimKW]

I test it and add chlorine as needed and then wait 12-24 hours before retesting. After shocking it on Friday it has held the chlorine level a little better.

I am not going to start using bleach in mine. I may at some later date, but I was fine with this method before and I should be fine again. I know people on this forum think that's wrong, but the place where I bought the hot tub says this is the way to go and not to worry about the CYA in a hot tub, that is for pools.

[gman]

JimKW

You say your sanitation method worked before and should be fine again, so you're going to wait before you stop adding dichlor or reduce your CYA. You're certainly entitled to follow whatever protocol you think is most appropriate. After all, it's YOUR tub and YOUR health and safety that are at risk, not mine.

However, here's a personal anecdotal story that you may want to consider. Given the preamble above, the essence of my story is obvious and predictable...neverthless....

A very good friend of mine had faith in her spa dealer. The dealer always provided her with good service. She trusted his advice and followed the dealer's recommended water maintenance protocol, which essentially required her to maintain her water chemistry by adding dichlor regularly. Her dealer reassured her that this protocol would be all she needed to keep her water safe. She maintained her tub as prescribed by her dealer. She tested regularly (with the typical test strips routinely recommended by many spa dealers) and added dichlor based upon her test strip results. Eventually, she had water issues and developed a rash. When I tested her water with a drop test kit, I found her CYA was over 250 ppm.

As you may well know, CYA acts as a buffer to slow the release of chlorine. The chlorine in the dichlor is consumed by combining with waste and contaminants, the CYA does not dissipate as chlorine and the level keeps increasing with each addition of dichlor. Consequently, with such a high level of CYA, my friend would need to add a lot more than the usual dose of chlorine to get the same sanitizing effect that that same dose of chlorine would have if applied to a tub with CYA in the 20 - 30 ppm range. Of course she didn't know that at the time.

I suggested that the high level of CYA may be the culprit to her water problems. At my suggestion, she changed her water. I helped her achieve good initial water chemistry and she monitored her CYA along with her FC, TA, and pH. She stopped using dichlor and switched to bleach when her CYA reached a little over 20 ppm. The end of the story is obvious. She has not had water issues since. (She's also saved some money on chemicals.)

Your CYA level isn't nearly as high as my friend's, but it could be if you continue adding dichlor. I can't imagine that you're changing your water often enough where a high level of CYA is not possible.

I know you have faith in your dealer and faith in your dealer's protocol. I understand your reluctance to change based upon advice from strangers whom you've never met accept via some online forum. Nonetheless, your method has not prevented your current water problems. Just food for thought.

Good luck and happy tubbing.

gman

Contented user of the dichlor/bleach method

[JimKW]

Thanks for the response. I'm not saying I won't ever switch to the limited use of dichlor method, but I am new at this and want to stick with what the dealers are saying for the time being. I put 1/2 oz of the chlorine with dichlor in yesterday morning and the level was still good this evening. So it's finally not losing the chlorine like it was.

I think the difference is the first time I filled it at the end of March we were using it every day sometimes multiple times a day so adding chlorine was expected. This time, since we are next to never using it, I didn't expect to put chlorine in as often.

So exactly what do you use to add chlorine if I don't use the product with dichlor I get from the dealer? I do have the Taylor k-2006 drop test kit. I use it, but I also use test strips for a quick reading. I find the strips fine for chlorine and PH. The kit does not give you much of the liquid you need to test cya and I am almost out of it. Any recommendations on where to get replacement chemicals?

Like I said I am new at this and trying to learn.

Thanks again,

Jim

[gman]

I just use regular Chlorox Bleach. Chlorox Ultra or other variants are not recommended because these contain lye. Just plain regular Chlorox. However, you can use just about any type of chlorine. However, the concentration of chlorine may vary with the brand or form. Therefore, the dosage will vary depending on the type of chlorine you purchase and its strength. A reasonable benchmark for regular Chlorox bleach is 3.5 ounces of Regular Chlorox bleach for every hour of one person usage of the tub.

You can also refer to your Taylor kit conversion table in the pool/spa instruction manual that accompanies your test kit. There is a table that tells you the amount of chlorine you need to add based upon chlorine concentration. I'm away from both my tub and my kit right now and I'm a bit tired, but if memory serves me correctly, Chlorox Regular Bleach would follow the conversion table for 65% strength chlorine. Others on this forum have done the actual math calculations and conversions, so if I'm wrong, I'm sure someone will chime in and provide the correct dosage. My apologies in advance if I've given you misinformation.

The short answer is Regular Chlorox Bleach.

As for Taylor test kit reagents...when you're running low, you can get those sent directly from Taylor Industries. Taylor will ship them directly to your home.

Good luck

gman

[waterbear]

As for Taylor test kit reagents...when you're running low, you can get those sent directly from Taylor Industries. Taylor will ship them directly to your home.

Good luck

gman

Link for Taylor Technologies ordering info.

Call 800-837-8548 for ordering.

[chem geek]

A reasonable benchmark for regular Chlorox bleach is 3.5 ounces of Regular Chlorox bleach for every hour of one person usage of the tub.

Without an ozonator, the rough rule-of-thumb is 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 7 teaspoons of non-chlorine shock (43% MPS) for every person-hour of soaking at hot (104ºF) spa temperatures, but that's just at guide and you really want to measure your chlorine and use enough so that after adding it after your soak you still have a measurable residual by the next time you soak.

[gman]

A reasonable benchmark for regular Chlorox bleach is 3.5 ounces of Regular Chlorox bleach for every hour of one person usage of the tub.

Without an ozonator, the rough rule-of-thumb is 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 7 teaspoons of non-chlorine shock (43% MPS) for every person-hour of soaking at hot (104ºF) spa temperatures, but that's just at guide and you really want to measure your chlorine and use enough so that after adding it after your soak you still have a measurable residual by the next time you soak.

Chemgeek,

Thanks for clarifying the dosage guide, in particular, the ozonator factor. My dosage amount recommendation was for a system that uses an ozonator 24/7. Since it's always on in my tub, I take it for granted. I forgot about its impact on dosage amounts and failed to include and disclose that factor. Good catch!

gman

[chem geek]

Yes, an ozonator can cut the chlorine demand in half, though the actual amount varies depending on how often you use the tub. In your case, it's somewhat less than half. For those who use the tub only occasionally, say once a week, an ozonator will actually increase the chlorine demand since ozone can oxidize chlorine to chlorate. So an ozonator makes sense if you use the spa more frequently, especially every day, or have higher bather loads, say soaking with several people every 2-3 days.

[NewB@Spa]

I have had my 400 gallon spa for almost a year and thankfully switched to the Dichlor/Bleach method after my disastrous first fill which turned out much like the friend above. My water has never been cleaner or safer. I can't imagine ever switching from this. As for the tester the Taylor Kit is good, but there is also another TFT Test Kit - TFT Test Kits which although a little more expensive at start up provides more tests, especially CYA, for your money. I have had my kit almost 9 months and I am just getting to need CYA test and Chlorine (FAS/DPD) refills. I will never, ever use strips again except for maybe testing salt (unstabilized chlorine adds salt). Do what you want, but I will tell you I am much happier - no Ph drift, no scaling, no irritation/rash.

[JimKW]

OK guys just to prove I do pay attention. I just took my readings again and I am now holding chlorine.

Here are my current readings:

Free Chlorine: 2.0 ppm

- Combined Chlorine 0.0 ppm

- Total Chlorine: 2.0 ppm

- pH: 7.6

- Hardness: 175 ppm

- Alkalinity: 100 ppm

- CYA: ~60 ppm

I will run out of the Reagent to test CYA in one more reading so I ordered a bigger bottle from Taylor. Two .75 oz bottles do not last very long.

Last night I just used a test strip and the Chlorine looked just a little on the low side so I added about an oz of Clorox bleach. I am going to add another oz right now and see what my reading is tomorrow. My hot tub is 483 gallons.

Chem Geek when you say 5 fluid ounces of 6% bleach how many gallon tub are you talking about? Since we are very rarely using the tub this time of year I figure I am safe just putting in an oz or two at a time and then reading the next day. It's pretty hard to get in a hot tub when it's 90+ degrees outside. I prefer going out on the boat and jumping into the lake to be honest.

[chem geek]

The rough rule-of-thumb with no ozonator of 5 fluid ounces of 6% bleach or 3-1/2 teaspoons of Dichlor or 7 teaspoons of non-chlorine shock (assuming 43% MPS) is for each person-hour of soaking so is what it takes to handle bather waste independent of spa size. This isn't about a sanitation level. You can use The Pool Calculator to calculate dosages to get to a specific Free Chlorine (FC) level for the number of gallons in your spa. For proper sanitation, you should shoot for roughly 4 ppm FC with 30 ppm CYA though many people add chlorine after their soak such that they have around 1-2 ppm FC at the start of their soak and they seem to do fine.

When not using the tub much, your chlorine demand may be around 25% of the FC per day, though this depends on your water temperature and will be a lower demand at lower temperatures. Basically, you can just see what your daily chlorine demand is even when you aren't soaking and add enough chlorine to always have a measurable residual. If you measure 4 ppm FC one day and the next day it's 3 ppm, then add 1 ppm. You could add chlorine every other day or so if you add more to make sure it doesn't get to zero.

[PaulR]

I will never, ever use strips again except for maybe testing salt (unstabilized chlorine adds salt).

All forms of chlorine add salt, although I believe the amount varies.

As a data point, last time I changed my water it had been close to six months but with relatively light usage. Salt level was around 1000.

--paulr

[chem geek]

All forms of chlorine produce salt because the chlorine breaks down into chloride ion which is salt. Some chlorine may outgss, but most gets broken down in the hot water oxidizing bather waste or chemicals in the water (including CYA, though slowly). For every 10 ppm Free Chlorine (FC) from any source of chlorine, it will get converted to 8.2 ppm salt when the chlorine gets used up. Bleach, chlorinating liquid and lithium hypochlorite add an additional 8.2 ppm salt upon addition so their total for every 10 ppm FC is a net result of 16.5 ppm salt.

So with a 4 ppm FC per day chlorine usage (around 35 minutes of one person soaking in a 350 gallon hot tub), this results in around 200 ppm salt per month. This is normally not a problem since after 6 months that is around 1200 ppm salt. Saltwater chlorine generator pools have around 3000 ppm salt. I wouldn't worry about salt in a hot tub until it got to at least 1500 ppm and that's only for tubs with cheap metal materials. Usually, you will be changing the water before the salt level gets very high.

Now if one had high bather load such as two people soaking for an hour every day in a 350 gallon tub, then that might require 14 ppm FC per day which would result in almost 700 ppm salt per month, but such high usage would probably need a water change after a couple of months with Dichlor-then-bleach though that's still about twice as long as using Dichlor-only where the water would start to turn in a month. For more normal lower bather loads, the Dichlor-only method usually lasts around 2-3 months before a water change while Dichlor-then-bleach lasts 4-6 months.