Trying To Understand - Correcting Issue In New Hot Tub

[squizzaroo]

Hi,

We bought a 410 gallon hot tub that we have been happily using since the beginning of April following the dealer's guidelines and using their chemicals, not really understanding how/why it works. 2 people have been using it for ~25 min every night at ~102 degrees, not showering beforehand. Occasionally our 2 year old will use it with one adult at 100 degrees for ~15 min. We went away for a week and came back to an odor in the tub, and I thought I saw a small area of green film on the surface but it was dark and I may have been imagining things due to the disgust of noticing the smell. I have read a bunch of the pinned topics and am planning to use the dichlor/bleach method going forward. I already ordered the Taylor chemical tester and have figured out what chemicals we already have and what we need to purchase, and would really appreciate some feedback/confirmation on my understanding and plan of action.

1) The new spa may have arrived with some contaminants in it that may make the addition of the sanitizer (dichlor that was given with spa) less effective earlier than it will with subsequent fillings, so spa is due for a water change

2) We had been ignorantly letting the chlorine go down to unmeasureable (0?) as measured on the provided test strips which means that bacteria has probably been growing on and off at least (after adding enough (3 TBL total) it is measurable on the strip). We had been using the non-chlorine spa shock once a week as instructed.

3) Just now when I added 2 tablespoons of dichlor to the water, it does not change the color on the strip. I added another 1 TBL and it did not budge still. This either means that there are so many contaminants that it is being used up right away OR there is something actively growing which is using it all up right away.Does it matter which is true?

4) I think I should run through the decontamination procedure prior to refilling due to the odor I noticed - agree that this is necessary?

5) I have seen references to Ahh-some (not an enzyme cleaner) and also to an enzyme cleaner - which should I use as the first decontamination step, or should I use Ahh-some and then the enzyme cleaner? If enzyme, is there a recommended one?

6) After decontamination, to balance and maintain the water, the chemicals I need are:

a) Dichlor = sanitizer = "chlorinating granules"

Dry acid = sodium bisulfate = "pH and alkalinity down"

c) sodium bicarbonate = baking soda = "pH and alkalinity up"

d) bleach - Clorox regular unscented

e) is that it? anything else to balance the water initially (ie calcium)? Is the potassium peroxymonosulfate ("non-chlorine oxidizing shock") going to be good for anything?

Thank you very much for any feedback!

[chem geek]

(deleted duplicate post -- see next post)

[chem geek]

Before you do the water change, I suggest you buy and use Ahh-Some. That will remove greases and biofilms that may have been their in the new spa from wet testing if not thoroughly dried out and from biofilms that formed when the spa went south on you.

As for you not getting a chlorine reading, try a tiny amount of chlorine in a jug of tap water and see if your test strips are OK. If they are (and you are getting a proper Taylor kit anyway) then yes your spa has a high chlorine demand and it doesn't really matter why. You need to decontaminate it. Use the Ahh-Some and you could superchlorinate as well if you want, again just before you dump the water and refill. You can do both at the same time (i.e. one after the other) without changing the water. I'd probably use the Ahh-Some first though if things are really bad you may need to do it more than once (i.e. change the water more than once). If that is the case, you can save the superchlorination for the last time before the last refill (if you can guess when that would be based on the amount of junk coming out from the Ahh-Some).

After you get your spa in shape, then water balance does mean increasing Calcium Hardness (CH) to 120-150 ppm to help prevent foaming. The MPS can be used as a supplemental oxidizer, but it's not necessary. If you already have it, you can use it along with your chlorine dosing. You can't use it by itself -- you should always have measurable chlorine in the water.

It looks like you've read and learned a lot. Just keep in mind that when using chlorine you have to add it regularly to maintain a residual. In that sense, it's more work. However, it does keep the spa in the best possible shape and with the Dichlor-then-bleach method that avoids CYA buildup you should be able to go at least twice as long between water changes compared to Dichlor-only.

[MoroccanBath Addict]

"Is the potassium peroxymonosulfate ("non-chlorine oxidizing shock") going to be good for anything?"

As I understand it, potassium peroxymonosulfate is ussually used for clearing water, thus allowing chlorine to work to sanitize the water rather than clarify the water, resulting in less chlorine needed.

Hope this helps.

[squizzaroo]

OK, thanks very much this is extremely helpful! A few more questions... Do I need a separate enzyme cleaner or should the Ahh-some do the trick?

As far as methods of sanitation go, my understanding is that there are 4 ways: 2-step bromine, 3-step bromine, Dichlor/bleach and dichlor only. Seems like there are pros and cons to each. Ideally, I'd like to do as little daily maintenance as possible but would rather keep the tub healthy so will do what is needed. We are using the tub a lot right now, maybe will taper off usage in the future since it is so new, but right now we want to go in every night. My calculations showed we should be changing the water every 68 days. Will that be reduced with the dichlor only method or will it be extended by the dichlor/bleach method? 3-step bromine sounds like the least day-to-to-day maintenance to ensure baeline levels are always present, except it still requires a shock with bleach after every use, correct? So it seems that regardless we will have to be dosing something (either bleach or dichlor) in there everytime we use it anyway to prevent the chlorine from being depleted. Is that correct or am I missing a simpler option?

FYI I did the superchlorination yesterday prior to reading your reply. The chlorine got way up, and then I tested it again this morning and it is down to 3 ppm. Will use the ahh-some and drain today.

[chem geek]

The non-chlorine shock (MPS) is an oxidizer, not a disinfectant (unless used in conjunction with silver ions in the Nature² system). So you can use it as an expensive supplement for oxidation, at least until you use it up.

You do not need a separate enzyme cleaner. Ahh-Some is all you need at most once per water change.

Yes, those are the four primary methods, but there is also Nature² (silver ions) with MPS. There are variants of chlorine and bromine systems by various manufacturers using cartridges (e.g. Frog for bromine). There is also Baquacil/Biguanide/PHMB but that is not as common and is expensive.

How did you calculate changing the water every 68 days? If you are using the "standard" Water Replacement Interval (WRI) formula that is (1/3) x (Spa Size in Gallons) / (# of persons per day), that assumes fairly short soaks of 20 minutes. So I presume you used that formula for 2 people. That would be roughly the time when using Dichlor-only. If you were to use Dichlor-then-bleach, you'd get roughly double (or more) the time between water changes. This is because you would avoid the CYA buildup from Dichlor that makes the chlorine less effective over time to the point where it oxidizes bather waste more slowly than you are adding it via usage so the water gets dull/cloudy. Note that if you are using the spa for more than 20 minutes, then you will need to change the water more frequently. Use "1/9" as a factor for Dichlor-only if you use "person-hours" in the denominator. Use "2/9" as the factor for Dichlor-then-bleach with person-hours. These are just rough estimates and you can change the water whenever you feel it is no longer fresh and clear.

The bromine methods still require adding some oxidizer after each soak unless you crank up your bromine tab output and you soak regularly and don't mind starting out with higher bromine levels during a soak.

I should point out that there are also automatic chlorine dosing methods such as using the ControlOMatic Technichlor saltwater chlorine generator. Even with this system, you may need to dose after a soak if you want to be able to start out the soak with a low 1-2 ppm FC chlorine level and just have the generator handle background dosing in between soaks.

[squizzaroo]

Ok, this is super helpful! I think with our usage (2 people ~5 times per week) I am going to have to treat so regularly anyway that the dichlor/bleach method makes sense. My plan is to try this method first and see how easy it is to maintain.

WRI: Yes that is how I computed the WRIs because most of the time 2 people use it for 1 jet cycle and get out. Then I found the (your) formula for Dichlor/bleach in another thread and computed that it's double the interval, which matches what you are saying so I think I understand the rough guidelines and the effect of dichlor only on water changes now.

Update on progress: So prior to the Ahh-some, i got the FC up to 10, which required a LOT of dichlor. Ran the Ahh-some, got some brown foam and slime, not really any black bits. Didn't seem so excessive that I needed to do it twice. Left the Ahh-some in there overnight (was that OK?) and dumped the spa in the mid-morning. Did not superchlorinate to 50 ppm and dump, figured I would see how setting it up goes prior to dumping a full tub-load again.

Ok, on fresh fill, with cold water in the 410 gal tub which we like to use at 102 degrees, measured: calcium = 20 ppm, added 20 Oz of "calcium increaser", thinking that would increase by 60 ppm up to 80 ppm, and measured 170 ppm afterwards, any idea why that happened?

I don't have borate test strips so no idea what that level is, they are on the way. Also my taylor kit did not come with the salt testing chemicals. Do I need those?

Then computed target TA to be 80 ppm. Measured 25 ppm, added 8.4 TBL baking soda, raised it to 80 ppm, but an hour later it was down to 70 ppm. Assuming measurement error give and take.

Then measured pH > 8.0, added 1 TBL dry acid, still ~8.0, then 1 more TBL, went down to 7.4. Seemed to stabilize at 7.6 an hour later, TA was still 70 ppm. Assuming measurement error again at some point or another and that these values are close enough.

The tub was still cold and warming up, but I needed to get the chlorine in (at this point 10 pm at night), so put in 2 TBL of dichlor. At 11:15 Measured pH 7.6, TA of 70 ppm, and FC of 10.5 ppm. Realized I really couldn't read the test strips at all (used them to compare to Taylor results and to sanity check myself) and so previously had a very poor idea what the TA or pH actually had been prior to the Taylor test kit. Also noticed that the water is SO MUCH CLEARER after the refill that it had been cloudy for awhile before the change. YUCK!

This morning at 8 am (~10 hours after FC dosed to 10.5 ppm), the tub is up at 102 degrees, and just measured the pH is 7.6 and the FC = 7.5. I am pretty sure this means I am already at >25% chlorine demand. I am not sure what the effect of the temperature is on the FC though, as it was dosed to 10.5 ppm at ~72 degrees and then tested this morning at 102 degrees to be 7.5 ppm, I am wondering if I should dose it back up to 10 ppm for the chlorine demand test at a constant temperature of 102 or figure that the chlorine demand will come out too high anyway and repeat the Ahh-some then super-chlorinate to 50 ppm and dump to start fresh. Would like to save the water if possible. What do you think?

Thanks very much for any pointers!!

.

[chem geek]

It does seem like one treatment with Ahh-Some in your case was enough and that there wasn't a need to superchlorinate. If your chlorine demand starts out fairly normal in the spa, then you'll know it's OK.

Do you have an ozonator? With no ozonator, you should find your 24-hour chlorine demand to be a 25% or lower loss in FC assuming your spa water stays warm/hot. With an ozonator, you may find that the loss is 50% or more because ozone reacts with chlorine to form chloride and chlorate salts.

Are you sure you added 20 ounces of calcium hardness increaser to your 410 gallon tub? That's way too much. Where did you get to add that much? Exactly how much to add depends on the product. With calcium chloride anhydrous 20 ounces weight (around 16 ounces volume) would raise the CH by 330 ppm while calcium chloride dihydrate would raise it by 250 ppm. So the product you used must be cut to be less pure, but even so...

If you accurately dose, you shouldn't need to test for borates since you replace them on every water change and there aren't any in tap water.

Your target TA should be 50 ppm, not 80 ppm. A lower TA will have less of a pH rise over time. The sticky may be wrong about that if it still says 80 ppm for TA. If you find your pH is stable at your 70 ppm TA, then you can just leave it since the initial use of Dichlor over time will lower the TA by about another 10 ppm. Worst case your adding acid to maintain pH will also lower the TA.

Yes, your chlorine demand is over 25% since it lost a little more than that just overnight. I'd just wait to see how it goes. There may just be a little leftover that chlorine is oxidizing OR you have an ozonator (do you have an ozonator?). If you have an ozonator, then that may explain the higher loss and that unfortunately will make it harder to maintain chlorine in the spa, though not impossible if you use it every day or two. You'll just need to dose high enough so that you still have a 1-2 ppm FC residual at the start of your next soak.

[squizzaroo]

I do not have an ozonator. I bet there is some leftover whatever that the chlorine is oxidizing, so will see how the FC consumption goes over the course of today. Tub smells and looks good right now.

Calcium - I read to add that much on the back of the bottle - it's liquid "calcium increaser" - i probably did my math wrong on that one - it says add 8 oz/500 gallon to raise calcium by 20 ppm. So starting out at 20 ppm, I thought I conservatively (ha!) would like to increase by 60 ppm to get to 80 ppm total. So I computed 3*(8 oz/500 gal) *410 gal = 19.7 oz. Instead it increased the calcium by ~150 ppm. What went wrong there, I still don't see the mistake.

Can I assume that there are 0 borates in the water from the hose and dose the tub with borax to get to 50 ppm? Is it OK to do that after I have balanced the water and added the chlorine? My husband loves the air jets so would like to get the advantage of the borates to stabilize the pH from aeration.

Both Nitro's approach to water maintenance and the dichlor/bleach in a nutshell currenlty says the target TA is 80 ppm, at least in the first post of each topic. It was fairly easy (aside from the calcium snafu) to balance the water with the TA at 70 ppm but I am taking notes on a worksheet so I can track what is happening over time so next time I refill I can dial it in better. Obviously the calcium went too high so next time it may be a little different too.

Hopefully I will end up looking OK in the baseline chlorine demand and then I can start working on how much to dose after each use. I have found that going back and rereading topics over and over again once I've learned some more is helping with the understanding. I appreciate your helpfulness and patience as I am sure you have answered these questions many times!

[chem geek]

You calculated correctly, but maybe they are wrong in their calculation. Was the product Rendezvous Liquid Calcium Hardness Up? If so, it says 1 ounce in 500 gallons raises CH by 7 ppm. So 8 ounces would raise CH by 56 ppm. So 3 times that would be 168 ppm CH.

There won't be any borates in the fill water so yes assume 0 to start and dose to get to 50 ppm, but use boric acid since it's easier than adding borax and acid. You can get boric acid at Duda Diesel or The Chemistry Store.

The TA in those pages is wrong and should say 50 ppm. Unfortunately, Nitro is not around here anymore to update it and only he (or an admin, I suppose) can change it. The TA needs to be lower and borates are not optional in order to have the pH be more stable when there is aeration.

[squizzaroo]

The calcium increaser brand is "hot tub things calcium increaser." Maybe I didn't shake it up well enough?

OK, I saw a thread that references the forum "trouble free pool" and those summaries are updated with the TA of 50 ppm you mention. Roger on the boric acid.

So I tested the tub again at 9 pm (22 hrs after raising to 10.5 ppm FC), and the readings were FC = 5.5 ppm, pH = 7.6, and TA = 60 ppm. So I bet there was some leftover whatever that the chlorine was oxidizing Does this level seem OK to you that I am out of the woods on needing to re-decontaminate? I went in for ~20 min, and then measured the FC to be ~4.25 ppm, which means I am about average clean I guess. i added 1 TBL dichlor because I knew I was not going to be able to measure 2/5 of a TBL accurately and figured with the previous issue wouldn't hurt to get close to 10 ppm again. Not sure what to do now but measure again in the morning and before and after each soak to try to figure out our combined soak usage, this one was unusual because my husband didn't go in. The water was beautiful BTW. How long do I need to leave the cover off after adding dichlor/bleach?

I am a little unclear on maintenance after I get rolling. From the guide it says to maintain FC at 3-6 ppm and then shock to 12 ppm once per week (I presume I do this when I know I won't get in so there is time to dissipate prior to entry). Nitro suggests using the MPS to "shock" once a week - why and would it be at the same time as shocking with dichlor/bleach to 12 ppm?

[chem geek]

Well a roughly 50% loss over roughly 24 hours is higher than normal, but at least it's holding chlorine and is better than before. You can see how things go from here.

There isn't much point measuring after a soak. Chlorine will get used up during a soak. What you want to do is measure before your soak, add chlorine afterwards, then measure again before the next soak or 24 hours later, whichever comes first. You want to add enough chlorine after your soak so that you still measure a residual of chlorine 24 hours later. Usually people want to start their soak with 1-2 ppm FC, but until you get a better handle on your chlorine usage you might target somewhat higher.

You should not need to shock if you add chlorine regularly with the Dichlor-then-bleach method. Again, that might be something old in Nitro's thread.

[MoroccanBath Addict]

Squizzaroo, how is it going with you now? Everythings fine buddy? Hope you're enjoying your spa.

[squizzaroo]

Things have been fantastic, thanks for asking! So far it has been about a month and a half and I have had no issues with clouding, foaming or anything. We use the thing almost every night so it's been getting a lot of use and it's pretty easy to maintain since we are down there so often. I really like this method, thank you for all the help!! Looking forward to the next refill so I can get it even cleaner.