Jump to content

Dichlor/bleach Method In A Nutshell


Nitro
 Share

Recommended Posts

How big is your tub and how are you testing? There is a known interference with phenol red used to test pH and high sanitizer levels. 3 to 4 Tbls. of 7.5% bleach will raise 100 gal. 9 to 12 ppm over the starting point (usually around 3 to 5 ppm) and pH test will show this interference when sanitizer is over 5 to 10 ppm, depending on who makes the reagent. The effect of the interference in that the pH will read high when it is not. Your pH is not rising, it's still 7.4 and my guess is that you free chlorine is high when you get the high pH reading

  • Like 1
Link to comment
Share on other sites

my tub is 375 gallons.  I am testing with a taylor.  Everything your saying makes sense, except my sanitizer never tests very high.  If I put a couple tbs of muriatic acid in, my ph tests 7.4.  Next day the PH tests over 8 again.  Only thing I am adding is Bleach, so that is why I am thinking the bleach is the cause.  Thank you for the time and knowledge.  It's a bit frustrating when you have all your numbers right where you want them and then only one goes crazy on ya.

Link to comment
Share on other sites

On 7/8/2022 at 8:51 AM, RHeller1 said:

I am testing with a taylor. 

Which kit?
All the DPD based kits such as the K-2005 can bleach out at high sanitizer levels (unless you dilute the sample and make the appropriate calculations on the reading) leaving you to believe that the sanitizer is much lower than it really is. The only kit that is immune to this until sanitizer gets to extremely high levels is their FSD-DPD testing method found in the K-2006/2106 kits and as a standalone kit. OTO testing (which only tests total chlorine) will also be immune to bleachout from high sanitizer.

Performance bleach is fine and will not cause the pH rise you are seeing.


Based on what you have said so far the most logical explanation is that you are testing with DPD, your sanitizer is much higher than you think causing a partial bleachout of the DPD which leads you to think your sanitizer is low when it is actually high. The high sanitizer is causing the phenol red indicator to convert to chlorophenol red which has the same color changes as phenol red but test a pH range of  4.8 to 6.7 so when the pH indicates that it's 8.0 all you really know is that it's greater than or equal to 6.7 and when you add the acid you are bringing the pH below 6.7 so you are getting a different pH reading that is equivalent to the 7.4 but is much lower.

If you are using FAS-DPD testing then a full set of test results might give us more information.

Link to comment
Share on other sites

I am using the k-2006

So since my first post, I have quit using the clorox performance bleach and went with liquid pool chlorine.  

My PH has read 7.6 the last 2 days, my TA is at 60, my CYA is at 38 and my chlorine is at 4ppm.  I cant explain this, but something in my tub does not like performance bleach

 

 

 

Link to comment
Share on other sites

15 hours ago, RHeller1 said:

my CYA is at 38

This reading is impossible to achieve with a Taylor K-2006. The test has a precision of +/- 10 ppm and the scale is logarithmic so you cannot interpolate readings between the marked ones on the CYA test tube. Are you using a 10 ml or 25 ml sample for the chlorine tests? Is your 4 ppm reading for chlorine Free chlorine or Combined Chlorine? Are you using MPS?

The only thing different about performance bleach is the inclusion of Poly(Diallyldimethylammonium Chloride) and Polyacrylic Acid, which are common ingredients in many pool clarifiers. They are coagulants that cause small particles to clump together that, in laundry, prevent dirt from redepositing back on clothes and in pools and spas, cause them to become large enough to be filtered out by the filter. neither would have an adverse affect on pH. All other ingredients in performance bleach besides the sodium hypochlorite, are also found in pool chlorine and other liquid sodium hypochlorite products, either as breakdown products as the bleach weakens with time or for manufacturing and stabilizing (sodium chloride (salt), water, sodium hydroxide, sodium chlorate, sodium carbonate).

Link to comment
Share on other sites

ok, say 40, but it was right past the 40 line for CYA.  I am using a 25ml for my chlorine test.  I use MPS once a month.  I understand pool chlorine and bleach are basically the same, thats what is bugging me.  

 

1848647980_20220713_1700211.jpg

Link to comment
Share on other sites

13 hours ago, RHeller1 said:

I am using a 25ml for my chlorine test.

no need for that much precision (.2 ppm is overkill and can lead to error because of the number of drops to count.)

 

Use the 10 ml sample, 1 scoop of DPD powder and then each drop will be equivalent to .5 ppm FC. Add 5 drops of DPD reagent 3 for the CC test and then each drop will be .5 ppm combined chlorine. You want to shock or add MPS when the CC is persistant and greater than .5 ppm (> or = 1 ppm). If you are using MPS then you need to get the R-0867 Deox Reagent to remove the interference (MPS will test as combined chlorine). The 2 oz. kit

https://taylortechnologies.com/en/uproduct/reagent-pack-monopersulfate-interference-remover-for-2000-series-kits-w-2-oz-re?id=K-2042

is a better bargain than the .75 oz kit

https://taylortechnologies.com/en/product/test-kits/reagent-packmonopersulfate-interference-remover-for-2000-series-kits-w-75oz-rea--K-2041

but it won't fit in your plastic case.

 

On 7/8/2022 at 8:51 AM, RHeller1 said:

Next day the PH tests over 8 again.

Just noticed this rereading the posts. What is your TA? (or what was it when you were having the pH problem?)

Link to comment
Share on other sites

  • 1 month later...

New to cedar tubs. On my third refill and can't get it right. Seems like dichlor/bleach method is the way to go but I installed a clear blue mineral ionizer first. Do I scrap the ionizer or will it compliment the method? Any feedback is welcome. 

Tried the @ease chlorinator with zero success. Doesn't register any chlorine. Ionizer has been turned off per my local spa guys recommendation. But he also swore the @ease thing was great for cedar tubs so..

just got a TF100 test kit. 

drained because of so much tannin and test results of:

FC .5

CC .5

TC 1

Calcium hardness 250

TA 130

CYA couldn't read, <20

PH 6.8

Link to comment
Share on other sites

Sorry, I dont know anything about the clear blue ionizer or the @ease chlorinator, but wouldn't expect any issues with the ionizer and the dichlor/bleach method.

Are your test results on your new water or are they pre-draining?  If on the new water, you are going to want to get your TA down in the 60-70 range for bleach.  Where your pH is low now, you should aerate (if you can with a cedar tub) to get that up into the 7.2-7.5 range before dropping the TA.  If your CYA is below 20 you should use dichlor until you are into the 20-30 range.  Your FC is low and your water should be shocked to get rid of that CC.

Link to comment
Share on other sites

11 hours ago, dashmer said:

Sorry, I dont know anything about the clear blue ionizer or the @ease chlorinator, but wouldn't expect any issues with the ionizer and the dichlor/bleach method.

Are your test results on your new water or are they pre-draining?  If on the new water, you are going to want to get your TA down in the 60-70 range for bleach.  Where your pH is low now, you should aerate (if you can with a cedar tub) to get that up into the 7.2-7.5 range before dropping the TA.  If your CYA is below 20 you should use dichlor until you are into the 20-30 range.  Your FC is low and your water should be shocked to get rid of that CC.

Thanks Dashmer. Those readings were before I dumped and refilled. Refilled yesterday and ran the circulation pump and turned on the ionizer. 

Just tested:

pH - 7.8

TA - 120

So sounds like I need to lower my pH (w/ pH reducer) and lower my TA. 

Questions:

  1. What is the preferred way to lower TA? My pH reducer contains sodium bisulfate, will that do?

  2. I can’t seem to find any of the links that Nitro references in his original post - looking for the TA down guide and the full dichlor/bleach method guide - a point in the right direction is appreciated)

  3. You mentioned aerating to affect pH. I don’t have aerating jets, just a circulation pump/filter. Does that do the trick?

  4. At what point should I concern myself with the copper level referenced in the ionizer manual (it says, “maintain chlorine or bromine at 2.3ppm unitl copper is at 0.2ppm-0.4ppm”)

  5. Will you continue to help me even though I’m completely clueless? If yes, thank you!

I really appreciate your time and feedback. 




 

Link to comment
Share on other sites

10 hours ago, ColoradoJohn said:

What is the preferred way to lower TA? My pH reducer contains sodium bisulfate, will that do?

I use a pH down product that I know to be a dry acid (which may very well be sodium bisulfate).  This question would be better answered by one of our forum experts.

As a side note, my comments to you are from the perspective of someone who has experience with a portable acrylic hot tub.  I don't know if any of these processes or products are unsuitable for cedar tubs.

10 hours ago, ColoradoJohn said:

I can’t seem to find any of the links that Nitro references in his original post - looking for the TA down guide and the full dichlor/bleach method guide - a point in the right direction is appreciated)

I don't recall reading a "guide" and I dont know where you could find them, but the procedure is covered very well in the text of the stickies at the top of this forum....both lowering TA and the dichlor then bleach method. You would benefit from reading those posts.  I think I read them in their entirety when I got started over a year ago. Pay special attention to entries by "Chem Geek" and "Waterbear."

10 hours ago, ColoradoJohn said:

You mentioned aerating to affect pH. I don’t have aerating jets, just a circulation pump/filter. Does that do the trick?

Circulating the water would be the next best thing to aeration but make take longer to see the pH rise. Use the highest setting you have.  Others may have better advice on this situation.

10 hours ago, ColoradoJohn said:

At what point should I concern myself with the copper level referenced in the ionizer manual (it says, “maintain chlorine or bromine at 2.3ppm unitl copper is at 0.2ppm-0.4ppm”)

I believe an ionizer uses metals as a supplementary sanitation method.  From what I have read, metals can kill bacteria but they take a long time to do it, hence the reason that you need to maintain a Cl or Br level. To keep things simple while you get your water balanced, I would not concern myself too much with the ionizer.  Use the dichlor/bleach method for sanitization.  You could bring the ionizer back into the loop later..it is not needed right now.

10 hours ago, ColoradoJohn said:

Will you continue to help me even though I’m completely clueless? If yes, thank you!

Someone will jump in to help if not me.  Maybe one of the big guns (waterbear):) 

 

Good luck.

Link to comment
Share on other sites

Lowering TA can be done with either muriatic, sulfuric, or dry acid. Dry acid is sodium bisulfite and when dissolved in water forms sulfurous acid.

The procedure to lower TA is here:

https://www.poolspaforum.com/forum/index.php?/topic/28846-lowering-total-alkalinity-howto/

If you don't have jets it can still be done, it will just take longer. worst case, just get into the tub and splash. If you can rig a piece of PVC pipe with a right angle to your return so it shoots the water into the air and then falls back into the tub that will work. You want surface agitation to facilitate the outgassing of CO2.

Link to comment
Share on other sites

On 9/4/2022 at 3:33 PM, waterbear said:

Lowering TA can be done with either muriatic, sulfuric, or dry acid. Dry acid is sodium bisulfite and when dissolved in water forms sulfurous acid.

The procedure to lower TA is here:

https://www.poolspaforum.com/forum/index.php?/topic/28846-lowering-total-alkalinity-howto/

If you don't have jets it can still be done, it will just take longer. worst case, just get into the tub and splash. If you can rig a piece of PVC pipe with a right angle to your return so it shoots the water into the air and then falls back into the tub that will work. You want surface agitation to facilitate the outgassing of CO2.

Thanks @waterbear . I used the pH down (sodium bisulfite) that I have and it worked to lower TA. I made a venturi aerator that I'm pretty proud of and it did a good job aerating to raise pH. 

Currently:

TA 60 ( I think- see my 2nd question below)

pH 7.5

1. Is the dichlor/bleach method perfectly adapted for cedar tubs is there anything I need to do differently?

2. Reading TA- test kit instructions say you measure when it turns to red. My solution goes from green to clear to pink to red (each separated by one drop). Do I take my measurement when it goes from clear to pink or do I add another drop to make it properly red?

3. Does temperature affect of the chemical readings? I only heat my (wood fired) tub when I want to use it. 

4. How many days can I spend adjusting pH and TA before I have to sanitize? In other words, is it okay if it takes me 4 days before getting TA and pH adjusted so that I can proceed to the next steps? 

5. Borates = Borax? (at least for this purpose)

Thanks in advance to anyone willing to help me out. 

Link to comment
Share on other sites

On 9/8/2022 at 9:33 PM, ColoradoJohn said:

eading TA- test kit instructions say you measure when it turns to red. My solution goes from green to clear to pink to red (each separated by one drop). Do I take my measurement when it goes from clear to pink or do I add another drop to make it properly red?

Keep adding drops until the last drop added produces no additional change and then don't count that last drop. In other other words, you've added 7 drops and it's red, You add one more drop for a total of 8 drops  and the red stays the same, Don't count the last drop, you reached your endpoint at 7 drops.

On 9/8/2022 at 9:33 PM, ColoradoJohn said:

Does temperature affect of the chemical readings? I only heat my (wood fired) tub when I want to use it. 

depends on the test, Testing should really be done with room temperature samples so if you are testing before heating and it's not freezing cold you are good. If the water is cold bring the sample indoors until it reaches room temp. and then test.

 

On 9/8/2022 at 9:33 PM, ColoradoJohn said:

How many days can I spend adjusting pH and TA before I have to sanitize? In other words, is it okay if it takes me 4 days before getting TA and pH adjusted so that I can proceed to the next steps? 

You can adjust TA with sanitizer in the water as long as it's not at shock level. With Taylor reagents sanitizer should be below 10 ppm, with Pentair reagents 5 ppm.

 

On 9/8/2022 at 9:33 PM, ColoradoJohn said:

Borates = Borax? (at least for this purpose)

borax (soidum teteaborate decahydrate) , sodium tetraborate pentahydrate, or boric acid. Both penahydrate forms will raise pH so need acid (either muriatic or dry) added to maintain the pH in proper range. Boric acid will slightly lower pH (which quickly goes back to where it was with some aeration. As long as your pH is above 7.4 the slight lowering can be ignored.) Boric acid is more expensive than borax but still less expense than the commercial pentahydrate products like, Supreme and Optimizer. Gentle Spa, Supreme Plus, and Optmizer Plua are mixture sof boric acid and pentahydratre to make a pH neutral product. My recommendation is boric acid. Easy to dose, pH change is minimal, and price is reasonable.

 

On 9/8/2022 at 9:33 PM, ColoradoJohn said:

Is the dichlor/bleach method perfectly adapted for cedar tubs is there anything I need to do differently?

Not that I am aware of but I am by no means an expert on Cedar tubs.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...