Water chem for a newbie.

[dstoneburg]

I came from the pool and spa forum per chem geeks advise towards others. To start I purchased a used hotsprings classic. The tub is great, just got it set up and did the decontamination process as per Nitro outline. I have just today recently filled it up again with fresh water and it is currently heating. I plan on taking the temp to 100 and then testing. I have so many questions I don't know where to begin. First, does temp have any bearing on testing? I plan on using the dichlor/bleach method for sanitation. Do you guys have a favorite website to purchase your chemicals from, I am more-so looking for the bromates(?) or gentle spa that was recommended in the write-up.

So can someone help me out with a plan. I have a fresh refill in my tub, am currently bringing the temp up to 100 and then what? Should I test and toss up the results here and see where we are at?

 

[polyvue]

So can someone help me out with a plan. I have a fresh refill in my tub, am currently bringing the temp up to 100 and then what? Should I test and toss up the results here and see where we are at?

Welcome to TFP!

If you've read the excellent & comprehensive post by Nitro, How do I use Chlorine in my Spa (or pool)?, you already know more than I did during the entire 14 years I maintained my Hot Springs Classic spa (...dearly departed, it was traded for a pool and in-ground spa in 2007.)
Please do post a full set of test results and let the spa experts here give you their attention! :study:

If you need a good test kit, see recommended test kits.

Good luck to you.

 

[PaulR]

The only test I'm aware of that is affected by temperature is pH. Don't let your sample cool off before you test that. Everything else, it shouldn't matter.

Sorry I can't help with chem websites, I get my dichlor and dry acid from Leslie's and use plain old borax to do the borates.
--paulr

 

[duraleigh]

Most of you can tell, I am not a precision tester. I tend to ballpark most things and have good results.

I am not aware of temperature having any significant effect on pH. Whether my pool is 60 degrees or 85 degress the pH test seems to be the same. Am I overlooking a significant difference?

 

[Bama Rambler]

Re: [EDITED] Water chem for a newbie.

Here's a chart that show's it for a pH of 7 @ 25ºC
[EDIT] Edited to remove irrelevant data set
ºC pH
0
10
20
25
30
40
50
60
70
80
90
I didn't want someone looking at the numbers and not reading Chem Geeks reply about how they don't apply to pool chemistry [/END EDIT]

 

[duraleigh]

That's immeasurable on the pH tests that 99% of us use.

 

[PaulR]

I remember it being much more than that, on the order of 0.1-0.2 over a likely range of temperatures, although I can't remember where I got that. But from day one, people told me not to let the water sample warm up/cool down before testing pH. I wonder what the story is?
--paulr

 

[dstoneburg]

FC is zero because I have yet to add any chlorine. The temp currently is about 80. And this was without any aeration. What should my next steps be?

From Hot Tub -
FC – 0
Alk – 80
Ph – 7.2
TH - 50

As per Nitro's post it seems that the Alk is in a perfect range if my TH was 150(TH = CH Right?). The PH seems to be at a good level I am thinking because it will raise some when I actually turn the jets on. Am I confused with any of this? Naturally I am getting the same results from testing my hot tub as I am with testing my facet water. Is there anything I should do?

 

[polyvue]

What should my next steps be?

From Hot Tub -
FC – 0
Alk – 80
Ph – 7.2
TH - 50

As per Nitro's post it seems that the Alk is in a perfect range if my TH was 150(TH = CH Right?).

You need a better test kit. One that allows you to test for Cyanuric Acid (CYA), Calcium Hardness (CH) and both Free Chlorine (FC) and Combined Chlorine (CC). Strongly suggest that you procure one of the test kits discussed here. (Unfortunately, Total Hardness (TH) is not equivalent to Calcium Hardness (CH) -- but TH will always be => CH because it consists of CH plus magnesium.)

Your pH seems to be within range.

If you have a spa you might want to keep CH at at least 100 to 150 to reduce foaming.

Right. You want to increase Calcium Hardness to ~150 and then your Total Alkalinity (TA) would be on the money.

Naturally I am getting the same results from testing my hot tub as I am with testing my facet water. Is there anything I should do?

I think the most recommended procedure to get your sanitation level OK is to start off with granular DiChlor (this adds both chlorine and CYA) and then SWITCH to just chlorine (bleach) when the CYA gets to about 20-30 ppm. (Spa owners on this forum will correct me if I'm wrong on this.) This should work, but another way is to add liquid chlorine and cyanuric acid separately. On my old Classic spa I used Dichlor exclusively, but this is not the right way to go, since the sanitizer will become less and less effective over time (as the CYA builds up) and you'll have to empty the spa water much more often.

Well, spa owners on this forum, what have you all to say? :-D

 

[dstoneburg]

Thanks for such a quick reply. Those tests kits are a little more then I currently have available, is there anyway I could make do what I have for the next month and then get the test kit and do it the right way. I already have the test strips, granulated Dichlor, drop test kit for FC and PH, and the 6% unscented bleach from the decontamination procedure. Are my levels at an acceptable place to where I can use the Dichlor for the next month and then do it the proper way?

 

[chem geek]

The advice given so far has been excellent. Sorry I don't know a good online source for spa chemicals. With the quantities you will be using, even getting something from a local spa store isn't going to break the bank. You'll be saving a lot by using Dichlor-then-bleach and the amount of Gentle Spa needed for the Borates is very small so that bottle will last for many refills of the spa.

You can use your current test kit and if your chlorine level is higher than 5 ppm, you can use the dilution method to measure the higher values (i.e. dilute with distilled, bottled or filtered water and then multiply by your dilution rate such as 2x if you dilute 50:50). If you've already used Dichlor for a week or two, you can use bleach now if you like, but watch out for the pH rising. Until you get the Borates in the spa you may find the pH rising faster and may need to lower your TA lower to help prevent that (adding acid over time to keep the pH down will also lower the TA over time which is OK -- just don't let it get below 50 ppm).

Bama Rambler, let me know the source of the temperature data you showed. That is different then the numbers I have based on the temperature dependence of the various equilibriums in pool/spa water, but also just for water itself. I show the pH rising from around 7.5 to 7.75 going from 90F to 50F and vice versa when the water warms up in the spring. This is reasonably consistent with what I've seen in my own pool during fall/winter closing and during spring opening. I show that the pK_W for water from 90F to 50F goes from around 13.7 to 14.6 (it's 14.0 at 77F). This is also reasonably consistent with the ionization constants for water given in this Wikipedia article.

Richard

 

[PaulR]

I think the most recommended procedure to get your sanitation level OK is to start off with granular DiChlor (this adds both chlorine and CYA) and then SWITCH to just chlorine (bleach) when the CYA gets to about 20-30 ppm. (Spa owners on this forum will correct me if I'm wrong on this.) This should work, but another way is to add liquid chlorine and cyanuric acid separately. On my old Classic spa I used Dichlor exclusively, but this is not the right way to go, since the sanitizer will become less and less effective over time (as the CYA builds up) and you'll have to empty the spa water much more often.

Well, spa owners on this forum, what have you all to say? :-D

Dichlor is by far the easiest way to add CYA to something as small as your typical hot tub, and even up into the smaller Intex-size pools. You can get away with not running a CYA test afterward if you're brazen enough; dichlor reliably adds 9ppm CYA for every 10ppm FC. So you use dichlor until you've added a cumulative 25-35ppm FC, and then switch to bleach.

Using straight CYA is a real waste of money--it comes in multi-pound containers, and in a 350-gal tub you need about 1.5oz.
--paulr

 

[polyvue]

I already have the test strips, granulated Dichlor, drop test kit for FC and PH, and the 6% unscented bleach from the decontamination procedure. Are my levels at an acceptable place to where I can use the Dichlor for the next month and then do it the proper way?

If I can summarize Paul and Richard's answer: Yes.

But do add sanitizer (Dichlor) as soon as possible. If you know the number of gallons in your spa, you may be able to use the Pool Calculator to determine how much Dichlor to add. Or read the directions on the container. Add enough to achieve 5 ppm chlorine, then try to keep it in the 2 - 5 ppm range.

 

[Bama Rambler]

Richard, I got those numbers off the ph-7 standard pouch that came with my Hanna pH meter.

 

[chem geek]

Richard, I got those numbers off the ph-7 standard pouch that came with my Hanna pH meter.

So that pouch contains a pH standard so is a buffer system of some sort -- possibly a phosphate buffer. The buffer system is intentionally stronger and will tend to lock in pH more so than the normal carbonate buffer system in the pool. Also, the phosphate buffer itself may be temperature dependent. Combining all of this results in the numbers you showed. You can't compare that to what goes on in a pool nor in distilled water.

 

[dstoneburg]

So with my current readings, I could for the next month or so use the dichlor bleach method? So I am going to add dichlor tonight, any special way to do it? I am assuming with the cover open and jets running? Add little by little until I hit my 5 ppm? Once I hit my 30ppm of FC I then switch to bleach. Sounds too easy, tell me what I am doing wrong.

 

[dstoneburg]

This is a bit off topic but on the off chance someone does know, my hottub has a very minor leak, it pools where all the components are but it seems none of the components are getting wet, anywho, I wired the hottub using 12/2 onto a 20 amp breaker with a 20 amp GFCI ( This is a 110v ). For some reason the breaker keeps blowing, but not the GFCI. Now could this be caused by the hottub itself even though its not blowing the GFCI? Also it only blows the breaker after about 1/2 hour. Also is the wavemaster pump supposed to get hot? Would this indicate it may be going out? Cause the pump is nice and hot to the touch.

 

[polyvue]

So with my current readings, I could for the next month or so use the dichlor bleach method? So I am going to add dichlor tonight, any special way to do it? I am assuming with the cover open and jets running? Add little by little until I hit my 5 ppm? Once I hit my 30ppm of FC I then switch to bleach. Sounds too easy, tell me what I am doing wrong.

It is easy, don't worry. I would do exactly as you described... open the cover, run the jets and spoon in the Dichlor. Little by little or all-at-once, it doesn't matter.

One correction, though: You're not waiting until your Free Chlorine (FC) gets to 30 ppm... it's Cyanuric Acid (CYA) that you need to monitor. When it gets to 20 - 30 ppm, STOP using Dichlor and START using bleach as your sanitizer. This will take a few weeks, so by that time hopefully you'll be testing both CYA and chlorine with a good test kit. You'll be able to repeat this cycle (starting w/Dichlor, continuing w/bleach) the next time you drain and refill your spa.

This is a bit off topic but on the off chance someone does know, my hottub has a very minor leak, it pools where all the components are but it seems none of the components are getting wet, anywho, I wired the hottub using 12/2 onto a 20 amp breaker with a 20 amp GFCI ( This is a 110v ). For some reason the breaker keeps blowing, but not the GFCI. Now could this be caused by the hottub itself even though its not blowing the GFCI? Also it only blows the breaker after about 1/2 hour. Also is the wavemaster pump supposed to get hot? Would this indicate it may be going out? Cause the pump is nice and hot to the touch.

Sorry, this is not my area of expertise. Someone else will respond, please check back.

 

[PaulR]

So with my current readings, I could for the next month or so use the dichlor bleach method? So I am going to add dichlor tonight, any special way to do it? I am assuming with the cover open and jets running? Add little by little until I hit my 5 ppm? Once I hit my 30ppm of FC I then switch to bleach. Sounds too easy, tell me what I am doing wrong.

It is easy, don't worry. I would do exactly as you described... open the cover, run the jets and spoon in the Dichlor. Little by little or all-at-once, it doesn't matter.

One correction, though: You're not waiting until your Free Chlorine (FC) gets to 30 ppm... it's Cyanuric Acid (CYA) that you need to monitor. When it gets to 20 - 30 ppm, STOP using Dichlor and START using bleach as your sanitizer. This will take a few weeks, so by that time hopefully you'll be testing both CYA and chlorine with a good test kit. You'll be able to repeat this cycle (starting w/Dichlor, continuing w/bleach) the next time you drain and refill your spa.

Well, yes and no. The goal is to have CYA in the 20-30 range; but dichlor reliably adds 9ppm CYA for each 10ppm FC. So, you can indirectly measure your CYA by tracking how much FC you've added.

There is uncertainty all around, of course, so this is what I do:
1) Use the Pool Calculator to figure out how much dichlor it takes to reach 30ppm FC. (This assumes I've figured out my tub volume.)
2) Use dichlor to maintain FC until that much has been used up.
3) Verify CYA by running the CYA test.
4) Proceed with bleach.

This way I'm using only one CYA test, which conserves CYA reagent. If you figured your dichlor quantity within reason, your CYA will be within reason, and one test is enough.

You could also pre-measure the total dichlor needed into a separate container, and use that until it runs out. I'm too lazy to do that, I just figure it'll take N spoonfuls of dichlor and keep track. After a time or two I pretty much know how many spoonfuls it needs.
--paulr