Chlorine Smell?

[lagreca]

I've had my first spa up and running for about 5 days now (340 gallon FreeFlow Excursion). I've been following Nitro's chlorine method. So far so good, however I have a few questions...

My FC seems to drop from 5ppm to less than 1ppm everyday. I'm told this is because it is burning off from the high temperature of the water (102). Is this normal?

If so, should I be bumping the FC level to 8ppm or more, so it's higher than 1ppm when I get in?

Also the water seems to have a chlorine like smell, even when FC AND CC is less than 1ppm. It's not super strong, but you can definitely smell it while in the hot tub. However, when I get out and dry off, I don't smell chlorine on my skin. Is this normal?

Lastly, I dose the tub with di-chlor and MPS shock when I get out each night. I generally use about .4 oz of di-chlor and .1 oz of MPS. I dump them in at the same time while running the jets on high for 15 minutes. Is it ok to mix di-chlor and MPS together? Should I be shocking after every use?

I took a sample of water to Leslie pools today, and they ran all their tests and said everything looked good... I just want to make sure I'm doing everything properly. Thanks!

[chem geek]

It is not from burning off from the high temperature. Are you using the spa every day? If so, then the chlorine is getting used up from your bather waste depending on how long you soak. If you aren't soaking every day, do you have an ozonator? Ozone reacts with chlorine and uses it up more quickly when there is no bather load.

You do not need to bump the chlorine up before your soak, but you probably need to add more after your soak so that it lasts until your next soak or until the next time you dose (depending on how often you soak).

If you smell a faint chlorine smell, that is normal especially if you use aeration jets that tend to outgas the chlorine faster. Having a small 1-2 ppm FC at the start of your soak shouldn't be so much as to smell too much nor to smell when you get out so what you describe sounds normal.

It's OK to dose with Dichlor and MPS, but that isn't the Dichlor-then-bleach method and the MPS is far more expensive than bleach. 0.4 ounces of Dichlor would be 4.9 ppm FC in your 340 gallon spa and would handle around 42 person-minutes of soaking if there were no ozonator. The 0.1 ounces of MPS is almost negligible equivalent to only around 0.44 ppm FC.

If you read the Dichlor-then-bleach method, you would know that you don't "shock" after every use -- you simply add the appropriate amount of chlorine to handle your bather waste and you do this after every use. See Dichlor/bleach Method In A Nutshell.

[lagreca]

Yes, so far we have used the spa every day. Usually my wife and I for 30-45 minutes daily, and occasionally our kids will get in for a few minutes.

There is NOT an ozonator CURRENTLY installed, however I have purchased one, and we are waiting for it's delivery and install (it was out of stock). If I continue to use chlorine as my sanitizer, should I NOT install an ozonator? I was under the impression the ozonator would allow me to use less chemicals while still keeping the water clean. How will an ozonator change the dichlor/bleach method?

I also installed a Nature2 stick yesterday, basically for insurance, in case I let the chlorine drop too low.

One of my concerns is that we like to travel for days, if not weeks at a time, and so far the spa requires daily maintenance. Is there a way I can significantly and safely reduce that maintenance for when we are on vacation and it is not being used? For our week or longer trips, I could get someone to stop by once a week or so to dose the spa.

Yes, I am following the dichlor/bleach method. I was just putting a little MPS in after each use as insurance, because I wasn't sure things were going correctly (I'm still waiting for my Taylor kit to arrive).

Just to verify, tonight after two people soaked for 45 minutes, I added 10 fl oz of bleach to oxidize bather waste, plus 3 fl oz to bring the FC level to about 4ppm (it was 0 at the start of our soak). Roughly this was 1.6 cups of bleach. Does that sound correct?

When I add dichlor I run the jets on high for 15 minutes with the lid open. When I add the bleach, do I have to do the same, or since it's already a liquid can I just run the jets on low for a few minutes to mix? Do I have to leave the cover open when adding bleach?

Thanks for all of the help!

[chem geek]

So you have a bather load of 60-90 person-minutes while you've been dosing for closer to 40-50. So that explains why the chlorine is getting used up.

With soaking every day, the ozonator will help reduce the amount of oxidizer such as chlorine you need to add. When I refer to ozone reacting with chlorine, that only increases chlorine demand when you aren't using the spa. When you use the spa frequently as you do, the ozone oxidizes the bather waste so that chlorine doesn't have to. You'll probably find that you can add roughly half the required amount of chlorine (remember that you weren't adding the required amount).

As for going away, you can lower the spa temperature and shock with chlorine and turn off your ozonator (so when you install it, make sure there's an easy way to turn it on vs. off) then you can shock the spa to a higher chlorine level and probably have it last for a week, but it won't last for two. You could get a saltwater chlorine generator such as ControlOMatic Technichlor, but that requires a higher salt level and you'd need to make sure it doesn't void your spa's warranty. For those who don't use the spa often, bromine is usually better since ozone can generate bromine from a bromide bank and you can have bromine tabs in a feeder.

For two people soaking 45 minutes, that's 90 person-minutes so would need 7.5 fluid ounces of 6% bleach or 5-1/4 fluid ounces of 8.25% bleach -- of course, this being a rough estimate that is pretty typical. The 3 fluid ounces for the 4 ppm FC is for 6% bleach -- for 8.25% bleach it would be 2 fluid ounces. It sounds like you might have added more than you needed if you used 8.25% bleach (Clorox has switched to that concentration, but some off brands haven't yet), but then again you might have been behind even at the start of the soak so needed more. When you get your Taylor K-2006 kit, just measure and see where you are at.

When you add any chlorine to the spa after your soak, be it Dichlor or bleach, you want to keep the cover off. You want the circulation pump on, but don't need to run the spa jets unless that's the only way you can ensure circulation. The reason to keep the cover off is to let the bulk of the disinfection by-products outgas. Most get created in the first hour and most of those in the first 30 minutes when the spa water is hot. 15 minutes is better than nothing. If you open the cover and let it air out for a short time before your soak, then that will also help remove any gaseous products that build up under the cover. This process of having the cover open isn't a disaster if you don't do it, but it will tend to wear out your cover faster if you don't and it will smell more when you get in if you don't open it beforehand.

[lagreca]

I have been calculating the bather waste dosing as (source: http://goo.gl/thzO2i):

3-1/2 teaspoons of Dichlor

or

5 fluid ounces of 6% bleach (e.g. Clorox regular unscented)

or

7 teaspoons of MPS non-chlorine shock

per person per hour

So for my last calculation, I thought I was being very generous with the sanitizer: 2 (people) x 5 fl oz 6% bleach = 10 fl oz of 6% bleach to oxidize the bather waste. Then to bring the tub up to 4 ppm from 0 ppm chlorine, per thepoolcalculator.com, I added an additional 3 oz of 6% bleach (calculator only called for 2.8 oz). Converting 13 oz to cups, this would be 1.625 cups of 6% bleach. Do you still think I am under calculating my dosing?

As far as leaving for vacations, I think if I drop the temperature to 80 degrees, use the Nature2 stick, and shock, I should be good for a week at a time. I can have someone come over every week and re-shock it, to last for another week. I'm still a bit unclear on the whole shocking process. Can that be done with any of the sanitizers (bleach, dichlor, or MPS)? When you say to shock it, what PPM should you calculate the jump for? 10ppm or 20ppm?

I had a tough time deciding between chloring and bromine when starting my spa. I went with chlorine because that is what most people around me were using. However, with bromine being easier, I'm wondering if I should have went with that? Why is bromine not as good if you use your spa often?

As far as keeping the cover off when adding chlorine... My spa is currently connected to 110 electrical source, so the temp usually drops from 102 to 100 by the time we are done using it. That means the heater kicks on to bring it back to temp, and forces the low speed pump to run until its back to 102. Will that be sufficient for adding chlorine? I'll just set a timer for 15 minutes, then come back and close it up.

[chem geek]

You are correct with your calculation, but are you sure the bleach is 6%? If you are using an off-brand "regular" bleach, they are usually 3% or less. It is off-brand "Ultra" bleach that is usually 6% though now that Clorox has moved from 6% to 8.25% for their regular (in the U.S. -- in Canada they called this Ultra) it's hard to know what the off-brand bleaches are going to do. Also, you might have gotten behind in dosing previously or perhaps the tub was in bad shape before and has biofilms if you never decontaminated it with Spa System Flush or Ahh-Some.

The point is that if the chlorine goes to zero, you need to add more chlorine and increase the dosage, perhaps doing a decontamination. The rule-of-thumb for dosing is just that -- a rule-of-thumb. The real rule is to add whatever is needed so that you end up with a small amount of chlorine still left for the start of your next soak. Nevertheless, if your chlorine demand in a hot spa in between soaks (i.e. not the first day after your soak) is more than 25% FC loss per day, then you have something consuming chlorine in your spa you need to get rid of (with an ozonator, such daily FC loss often exceeds 50% of the FC level).

As for leaving, your plan sounds good. You can use bleach or dichlor, but if you use Dichlor you will build up the CYA level which is probably not what you want to do so using bleach would be better, assuming you've already got CYA in the water. MPS isn't a disinfectant by itself, but with Nature2 it is but only at hot spa temperatures so that won't work well at the cooler temperatures while you are away. As for shocking, 10 ppm FC is a decent target to safely last for the week, though Dr. Spa's recommendation in this post which gets you to around 6 ppm FC also works for a week as I show in this post.

If you use your spa every day or two, then bromine is not easier than chlorine, especially when you don't have an ozonator. When people say that bromine is easier, they are talking about not using the spa frequently -- say once or twice a week or only on weekends. The reason is that with a bromine tab floater you can get dosing of bromine in between soaks. With chlorine, you have to add it every day or two or perhaps at least twice a week assuming the water remains fairly hot (usually people keep the spa at least 90ºF or so in order to have it heat up quickly for use). With your heavy use (i.e. daily use), you would still need to add an oxidizer after your soak to create enough bromine to handle your bather waste. That is, your regimen would be no different with bromine than with chlorine. You would only notice the extra maintenance needed when you did not use your spa, as when you are going on vacation and need to raise the FC to last a week and to have someone come over to add more chlorine if gone for more than one week (though bromine tabs won't last forever either).

What you describe regarding the pump coming on at the end of your soak when you then add chlorine sounds fine. It's nice that it works that way.

[lagreca]

Tested my water this afternoon with a Taylor K-2006. Here are my results:

FC: 2.5

CC: 0.6

PH: 8

TA: 150

CH: 200

CYA: Didn't test today, but was 34 a few days ago

CH is high, should be 130-150

TA is high, should be 50-80

PH is high, should be 7.4-7.6

So I added 4 tsp of 31.45% Muratic Acid, which will hopefully bring the pH down to 7.5. I'm also aerating right now, to try and drop the TA a bit.

My ozone generator arrived in the mail today. I hope to have that installed in the next few days...

[chem geek]

OK, keep us posted, but you are on the right track.

[lagreca]

What does the CC tell me?

My current understanding is that low CC means waste is being oxidized. A high CC would mean the chlorine has binded with the waste but can't oxidize it. Is that correct?

What range do I want my CC to be within?

[lagreca]

I added 1 oz of 20 baume muriatic acid this morning, which was supposed to drop the pH to 7.4. I checked the pH this afternoon, and it was back up to 8. I did aerate a bit to try and bring the TA down, but I didn't think it was enough to bounce the pH back to 8. Maybe I need to drop the pH to 7.2 (1oz and 2 tsp of 20 baume muriatic) and try again?

I have NOT yet added Borates or any pH lock. First I need to buy some, and I don't want to add them until I have the pH at a desirable level. If and when I buy some 20 Mule Team borax, how much should I add to a 340 gallon hot tub to bring it to 55 ppm Borates?

[chem geek]

What does the CC tell me?

My current understanding is that low CC means waste is being oxidized. A high CC would mean the chlorine has binded with the waste but can't oxidize it. Is that correct?

What range do I want my CC to be within?

CC is a measure of chlorine bound to either ammonia or organics, but it doesn't means it can't oxidize it. It can mean that it is not finished oxidizing it. Some chemicals are faster to oxidize than others. You shouldn't test CC after your soak since it will generally be high, especially after you add more chlorine. You want to test it before your next soak when it should be at its lowest. If you find your CC to be high and notice a chloramine smell (not fresh like bleach), then you can raise the chlorine level (usually to around 10 ppm FC) and aerate the water to try and get rid of it. 0.6 is a little higher than the more typical 0.2 or 0.4, but it isn't a disaster, especially if you don't smell chloramines.

I added 1 oz of 20 baume muriatic acid this morning, which was supposed to drop the pH to 7.4. I checked the pH this afternoon, and it was back up to 8. I did aerate a bit to try and bring the TA down, but I didn't think it was enough to bounce the pH back to 8. Maybe I need to drop the pH to 7.2 (1oz and 2 tsp of 20 baume muriatic) and try again?

I have NOT yet added Borates or any pH lock. First I need to buy some, and I don't want to add them until I have the pH at a desirable level. If and when I buy some 20 Mule Team borax, how much should I add to a 340 gallon hot tub to bring it to 55 ppm Borates?

Aerating the water will generally make the pH rise and this happens much more quickly when the TA is higher so what you describe is not unusual, especially since you haven't added borates yet. This is why it's relatively easy to lower the TA with acid addition and aeration before you add the Borates.

You can use The Pool Calculator to calculate dosages. For the recommended 50 ppm Borates in 340 gallons, it takes 13 ounces weight or 14 fluid ounces volume of boric acid which you can get at The Chemistry Store, AAA Chemicals (larger size for pools) or DudaDiesel.

[lagreca]

Aerating the water will generally make the pH rise

I guess that would explain why you have to check the pH in a spa regularly, because most of the time the jets ARE aerated...

In the meantime I should just keep adding acid and aerating, until I see the TA drop to an acceptable level, and THEN add borates?

Is 20 Mule Team borax (http://goo.gl/YkvQux) the same as granular boric acid (http://goo.gl/IpC3jc)?

[chem geek]

Yes, you can just add acid and aerate and you'll see the TA drop. In 340 gallons, 0.87 fluid ounces (5.2 teaspoons) of 20 Baumé (31.45% Hydrochloric Acid) will lower the TA by 10 ppm so you can just keep track of how much acid you are adding rather than test the TA every time. When you think it's around 40-50 ppm TA, then that would be a good time to add the borates.

20 Mule Team Borax is not the same, though you can use it, BUT it requires acid to be added as well. It's usually easier to add the boric acid since it won't change the pH much. 20 Mule Team Borax raises the pH so you would add a little, then a little acid, then some more Borax, then some more acid, probably splitting dosage into thirds or fourths so you don't swing too extreme.

[lagreca]

I'm adding 2 tablespoons (1 oz) of 20 Baume muriatic acid, then aerating. My question now is, how long should I aerate to drop the TA 10 ppm? Or how long should I wait after adding the acid, before I add some more?

I ordered Granular Boric Acid, 5 lb from DD this morning. Hopefully I will have the TA down by the time it arrives.

Thanks for all of your help!

[chem geek]

The TA drops when you add the acid, not when you aerate. The purpose of the aeration is to raise the pH back up so that you can add more acid. The process goes faster if you do the process at lower pH, say bouncing between 7.2 and 7.0 pH though in a spa it's usually easy to have the pH rise fairly quickly when starting at pH 7.0.

[lagreca]

I used dichlor (0.6 oz) last night to bump the CYA slightly, however I think I put too much in, and tonight my spa is still at 10.5 ppm FC. The good news is that I got TA down to 80 ppm. As TA reaches my goal of 60 ppm, will pH tend to stabilize and not rise to 8 everyday? Do the borates help steady the pH as well?

However, even with the FC level high, my CC still measured 1.5 ppm. What would cause this? I still don't think I'm smelling chloramines. How can I lower the CC? Should I be concerned over this measurement?

[chem geek]

Yes, as the TA gets lower, the pH will rise more slowly and need less acid to bring the pH back down. Also, the 50 ppm Borates will have the pH rise even less -- roughly half as much as without borates -- though it won't change the amount of acid you need to add. So the combination of lowering TA and adding Borates is the winner since it cuts down the rate of pH rise and lessens the amount of acid needed.

The higher CC might mean you had things leftover to oxidize in your water. Why don't you keep the FC higher and have the cover off when you get a chance to help air out the spa. You can let the FC drop for your next soak. If you want to drop it more quickly, you can most easily do that by adding 3% hydrogen peroxide in a volume that is the same as the amount of 6% bleach needed for the amount of FC you want to drop. So you can use The Pool Calculator to calculate that volume.

[lagreca]

FC was down to 5 tonight, so we were able to get in.

I also was able to completely balance the water today!

FC: 5

CC: -

PH: 7.6

TA: 60

CH: 200

CYA: Calculated to be around 50-55, not tested

CSI: -0.11 (calculated at thepoolcalculator.com)

Boric acid should arrive this week.

I purchased new bleach this week that is 8.25% instead of 6% chlorine. I calculated that I should add 3.6 oz per person per hour to oxidize bather waste, is that correct?

Would it be possible to add this new common strength of 8.25% bleach to thepoolcalculator.com?

Thanks again for all of your help!

[chem geek]

Yes, I usually just say 3-1/2 fluid ounces per person-hour, but you'll adjust as needed so that you measure some FC before your next soak. The Pool Calculator is not owned by the original creator anymore, but PoolMath is available by the original creator and does have the 8.25% as a selectable bleach strength.

[lagreca]

I added 12 oz by weight of boric acid yesterday. We couldn't use the spa again last night because I accidentally over chlorinated it the day before...

FC: 5.5

CC: 1

PH: 7.2

TA: 60

CH: -

CYA: Calculated to be around 50-55, not tested

CSI: -0.51 (calculated at http://www.troublefreepool.com/calc.html)

Everything is looking pretty good, but the pH is slightly low. Pool calc says my CSI has "Potential to become corrosive to plaster". Since this is in a Spa, that is plastic, do I need to worry about manually raising the pH with baking soda? Am I in danger of damaging my heater or pipes? Or will it slowly rise on its own after regular use and aeration?

When I do accidentally over chlorinate the water, is it safe (I don't want to throw off any of the water chemistry) to use 3% hydrogen peroxide to neutralize the chlorine to bather safe levels, or should I just not use it and wait for the chlorine levels to drop on their own? If I do add hydrogen peroxide, roughly how long will it take to drop the chlorine level?

[chem geek]

You are correct that you need not worry about the low CSI for an acrylic spa. Your pH should rise from aeration. If it doesn't, you can increase it with chemicals -- 20 Mule Team Borax or Arm & Hammer Super Washing Soda (same as pH Up) if you have either. Metal corrosion occurs mostly from low pH, strong oxidizers, more dissolved oxygen, high chloride and sulfate levels, etc. Saturating the water with calcium carbonate to protect metal especially in pools and spas where water flow starts and stops is not at all clearly effective (read this link for a discussion of various indices and their applicability to metal corrosion).

Yes, if the chlorine is too high and you want to drop it more quickly, you can add 3% hydrogen peroxide in the same amount as the equivalent volume of 6% bleach for the amount of FC you want to lower. The drop will happen almost instantly, certainly within minutes with mixing.

[lagreca]

Can regular household Baking Soda be used, in place of Arm & Hammer Super Washing Soda or 20 Mule Team Borax, to increase the pH?

What is the maximum ppm that you would want to shock your spa to with bleach, before causing damage to the spa?

I am trying to keep TA between 50-80 ppm. What will happen if TA gets too low? What is the best way to raise it?

Leslie's Pool Store tested my water today and said that my phosphate level was too high, at 200 ppm. Is this a problem? How should I deal with it?

[chem geek]

Baking Soda will only raise pH significantly if it is low and it increases TA a lot. If the pH is already higher, it won't raise the pH much but still increases TA a lot. Basically, you normally use baking soda when you want to increase the TA, not the pH. Of course, if you want to increase both, with the TA increasing more, then you can use the baking soda.

Assuming you've got CYA in the water from initial use of Dichlor to build it up, then it would take a rather high level of bleach to be a problem. Assuming you've got at least 30 ppm CYA in the water and that the water temp is hot at 104ºF, then 10 ppm FC is equivalent to 1.6 ppm FC with no CYA. 20 ppm FC with 30 ppm CYA is equivalent to 3.9 ppm FC with no CYA (again at 104ºF). So you'd have to get higher than that before the chlorine starts to get strong to be a problem and even then it doesn't cause problems immediately -- the decontamination procedure uses very high chlorine levels, but for a relatively limited period of time (i.e. hours, not days).

By the way, when using the Dichlor-then-bleach method, you should not normally have to shock your spa except possibly after a fresh refill if the fill water isn't clean.

If the TA gets too low, use baking soda to raise it. If the TA gets too much below 40-50 ppm, then if you add any acid or use acidic sources of chemicals such as Dichlor (net acidic when accounting for chlorine usage/consumption), MPS, bromine tabs, then the TA can continue to drop and the pH can "crash" where it drops very quickly once the TA gets mostly used up. Such a low pH can corrode metal in the spa and possibly harm other surfaces.

Phosphates are irrelevant if you maintain a disinfectant level in the spa -- same is true in pools. Phosphates are an essential nutrient for algae, but chlorine kills algae faster than it can grow so long as the FC/CYA ratio is high enough. For pools manually dosed with chlorine, a minimum FC that is at least 7.5% of the CYA level will prevent algae from growing with no need for phosphate removers, algaecide, copper ions, enzymes, clarifiers, floculants or regular shocking. In spas, algae is far more rare due to the lack of light when the cover is on and the hotter temperatures especially if 100+ºF.