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Dichlor/bleach Method In A Nutshell

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Here is a quick reference to using the Dichlor/Bleach method. (i.e. Chlorine)

Please see the full guide for a detailed explanation. Top link below.

Initial Startup Procedure

1. Balance water by lowering TA to ~80 ppm. See link below (Lowering TA)

2. Aerate until pH is consistently 7.4-7.8. Lower TA if pH rises above 7.8. Raise TA if pH stays below 7.4.

3. Test Calcium, and make note of it. (100-150 ppm) is ok.

4. Add 50ppm Borates (highly recommended)

5. Shock tub to 10 ppm FC using Dichlor the first night after filling.

6. Wait 24 hours and test FC again in order to calculate Chlorine Demand. (See link below)

7. Start using tub.

8. Continue to use Dichlor after soaks (approx 7 ppm FC per person per hour) (or 3.5 tsp)

9. After you have added ~34 ppm FC (~30 ppm CYA) using Dichlor, switch to Clorox 6% unscented bleach. Takes about a week or so.

Ongoing Maintenance

After the initial startup procedure above, you'll basically do the following:

Check FC every day or two (and before soaks).

Check CD as needed (once a week to start).

Add plenty of Chlorine after soaks (and as needed) so FC NEVER drops to zero, and CD stays low.

Add MPS before/during high bather loads to help out the Chlorine, and keep CD low. (Optional but recommended)

Check pH once a week, and adjust TA as needed.

Rinse filter every week or two, depending on use.

Check CYA every 3 months, and raise by using Dichor if needed. CYA will drop slowly over time.

Use Sea Klear (clarifier) if you experience foam, or cloudy water.

Water Change

After 6 months, change water and start over.

If this is a new tub change water after the first month, then continue bi-yearly.

Consider using a Spa Flush to clean out pipes before draining 1-2 times a year.

Clean filter with TSP every water change.

Lastly, if you let the FC drop to zero for any length of time, the tub is prior owned or you're having serious medical issues (i.e. rashes etc.), consider doing a Decontamination. (see below)

Happy tubbing! :)

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Here is a quick reference to using the Dichlor/Bleach method. (i.e. Chlorine)

Please see the full guide for a detailed explanation. Top link below.

Initial Startup Procedure

1. Balance water by lowering TA to ~80 ppm. See link below (Lowering TA)

2. Aerate until pH is consistently 7.4-7.8. Lower TA if pH rises above 7.8. Raise TA if pH stays below 7.4.

3. Test Calcium, and make note of it. (100-150 ppm) is ok.

4. Add 50ppm Borates (highly recommended)

5. Shock tub to 10 ppm FC using Dichlor the first night after filling.

6. Wait 24 hours and test FC again in order to calculate Chlorine Demand. (See link below)

7. Start using tub.

8. Continue to use Dichlor after soaks (approx 7 ppm FC per person per hour) (or 3.5 tsp)

9. After you have added ~34 ppm FC (~30 ppm CYA) using Dichlor, switch to Clorox 6% unscented bleach. Takes about a week or so.

Ongoing Maintenance

After the initial startup procedure above, you'll basically do the following:

Check FC every day or two (and before soaks).

Check CD as needed (once a week to start).

Add plenty of Chlorine after soaks (and as needed) so FC NEVER drops to zero, and CD stays low.

Add MPS before/during high bather loads to help out the Chlorine, and keep CD low. (Optional but recommended)

Check pH once a week, and adjust TA as needed.

Rinse filter every week or two, depending on use.

Check CYA every 3 months, and raise by using Dichor if needed. CYA will drop slowly over time.

Use Sea Klear (clarifier) if you experience foam, or cloudy water.

Water Change

After 6 months, change water and start over.

If this is a new tub change water after the first month, then continue bi-yearly.

Consider using a Spa Flush to clean out pipes before draining 1-2 times a year.

Clean filter with TSP every water change.

Lastly, if you let the FC drop to zero for any length of time, the tub is prior owned or you're having serious medical issues (i.e. rashes etc.), consider doing a Decontamination. (see below)

Happy tubbing! :)

Hey Nitro, thanks for this. Two questions I have..... I put in Dichlor yesterday after the first fill, today my Fc was high, about 10ppm. Is there a way to lower it so I can use the tub soon? Also, what do the borates do? is that for ph balancing?

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I put in Dichlor yesterday after the first fill, today my Fc was high, about 10ppm. Is there a way to lower it so I can use the tub soon?

You can lower chlorine or bromine with sodium thiosulfate.

You can also use hydrogen peroxide to lower chlorine, but not bromine.

1 ppm of hydrogen peroxide will neutralize 2.08 ppm of chlorine.

0.54 fluid ounces of 3 % hydrogen peroxide in 264 gallons of water will neutralize 1 ppm of chlorine.

0.82 fluid ounces of 3 % hydrogen peroxide in 400 gallons of water will neutralize 1 ppm of chlorine.

Also, what do the borates do? is that for ph balancing?

Borates are used to provide pH buffering.

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Here is a quick reference to using the Dichlor/Bleach method. (i.e. Chlorine)

Please see the full guide for a detailed explanation. Top link below.

Initial Startup Procedure

1. Balance water by lowering TA to ~80 ppm. See link below (Lowering TA)

2. Aerate until pH is consistently 7.4-7.8. Lower TA if pH rises above 7.8. Raise TA if pH stays below 7.4.

3. Test Calcium, and make note of it. (100-150 ppm) is ok.

4. Add 50ppm Borates (highly recommended)

5. Shock tub to 10 ppm FC using Dichlor the first night after filling.

6. Wait 24 hours and test FC again in order to calculate Chlorine Demand. (See link below)

7. Start using tub.

8. Continue to use Dichlor after soaks (approx 7 ppm FC per person per hour) (or 3.5 tsp)

9. After you have added ~34 ppm FC (~30 ppm CYA) using Dichlor, switch to Clorox 6% unscented bleach. Takes about a week or so.

Ongoing Maintenance

After the initial startup procedure above, you'll basically do the following:

Check FC every day or two (and before soaks).

Check CD as needed (once a week to start).

Add plenty of Chlorine after soaks (and as needed) so FC NEVER drops to zero, and CD stays low.

Add MPS before/during high bather loads to help out the Chlorine, and keep CD low. (Optional but recommended)

Check pH once a week, and adjust TA as needed.

Rinse filter every week or two, depending on use.

Check CYA every 3 months, and raise by using Dichor if needed. CYA will drop slowly over time.

Use Sea Klear (clarifier) if you experience foam, or cloudy water.

Water Change

After 6 months, change water and start over.

If this is a new tub change water after the first month, then continue bi-yearly.

Consider using a Spa Flush to clean out pipes before draining 1-2 times a year.

Clean filter with TSP every water change.

Lastly, if you let the FC drop to zero for any length of time, the tub is prior owned or you're having serious medical issues (i.e. rashes etc.), consider doing a Decontamination. (see below)

Happy tubbing! :)

Hey Nitro,

Great quick ref. guide. Thanks. BTW, I adjust the calcium hardness first then pH & TA. Is that not the correct procedure? The CH will dictate the needed pH & TA.

Also, I add BORAX (as borates). I use it to raise pH when/if it drops but don't go out of my way to use it as a buffer. Do you think it warrants a step in the process?

Greg

BTW, just over one month and a half now using this exact formula and things are looking great. I barely need to adjust anything...(using allot of bleach though ;-)

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Hey Nitro,

Great quick ref. guide. Thanks. BTW, I adjust the calcium hardness first then pH & TA. Is that not the correct procedure? The CH will dictate the needed pH & TA.

Also, I add BORAX (as borates). I use it to raise pH when/if it drops but don't go out of my way to use it as a buffer. Do you think it warrants a step in the process?

Greg

BTW, just over one month and a half now using this exact formula and things are looking great. I barely need to adjust anything...(using allot of bleach though ;-)

You can adjust CH before or after. Unless it's much lower than 100ppm, I wouldn't touch it. Just make note.

Using the tub's jets/air should raise pH if TA is too high, so I'm not sure the need to use BORAX, other than to add Borates during startup.

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In Step 4, adding borates, since pH has already been balanced would it be best / easiest / most direct to use boric acid since it is more pH neutral? I've seen mixed info on Borax - some say it raises pH, others say no effect - could someone please clarify? If Borax raises pH I think I'd rather use boric acid rather than adjust pH back down w/ dry acid or muriatic acid. Thanks!

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Yes, it is certainly easier to use boric acid which is only slightly acidic or use Proteam Gentle Spa which is mostly boric acid and is pH balanced (fairly neutral). Alternatively, you can use a separately added combination (adding some of each, back and forth) of Muriatic Acid (or dry acid) and 20 Mule Team Borax which is less expensive, but as you point out it will have the pH swing more and probably need a final adjustment unless you measure very carefully.

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Yes, it is certainly easier to use boric acid which is only slightly acidic or use Proteam Gentle Spa which is mostly boric acid and is pH balanced (fairly neutral). Alternatively, you can use a separately added combination (adding some of each, back and forth) of Muriatic Acid (or dry acid) and 20 Mule Team Borax which is less expensive, but as you point out it will have the pH swing more and probably need a final adjustment unless you measure very carefully.

Thanks Chem Geek for this response and all of the other good info that you provide here!

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One question on what the chlorine liquid bleach does to pH. If the liquid bleach has a pH of between 11.2-13, then doesn't this raise the pH levels in the spa too much over time and how should I get the pH down without bringing TA down too much?

I have been using this method for over a month, but had a big pool party and threw way too much Dichlor in to sanitize afterwards so I had to dump the water and start over, so I never got to see how high the pH would get with this method. I certainly like the cost savings and simplicity of this method.

TIA

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Though the addition of a hypochlorite source of chlorine such as chlorinating liquid, bleach, Cal-Hypo or lithium hypochlorite has the pH rise, the consumption/usage of chlorine is an acidic process so the pH drops back down when this occurs (technical details in this post). Any net pH rise comes from two sources: 1) outgassing of carbon dioxide, which occurs faster at higher TA and lower pH (see this table) and higher aeration or 2) from the small amount of "excess lye" in bleach and chlorinating liquid. Clorox Regular unscented 6% bleach has the least amount of excess lye in it. Off-brand Ultra bleaches often have more so would tend to have the pH rise more quickly. Maintaining a lower TA (down to 50 ppm, if needed) and using 50 ppm Borates helps reduce the rate of pH rise.

I use only 12.5% chlorinating liquid in my pool, yet the pH is stable only needing a small amount of acid added every month or so.

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Though the addition of a hypochlorite source of chlorine such as chlorinating liquid, bleach, Cal-Hypo or lithium hypochlorite has the pH rise, the consumption/usage of chlorine is an acidic process so the pH drops back down when this occurs (technical details in this post). Any net pH rise comes from two sources: 1) outgassing of carbon dioxide, which occurs faster at higher TA and lower pH (see this table) and higher aeration or 2) from the small amount of "excess lye" in bleach and chlorinating liquid. Clorox Regular unscented 6% bleach has the least amount of excess lye in it. Off-brand Ultra bleaches often have more so would tend to have the pH rise more quickly. Maintaining a lower TA (down to 50 ppm, if needed) and using 50 ppm Borates helps reduce the rate of pH rise.

I use only 12.5% chlorinating liquid in my pool, yet the pH is stable only needing a small amount of acid added every month or so.

Let's say I want to drain, clean, and refill and go straight to bleach, bypassing the dichlor step. Can I just go out and buy some CYA and immediately bring the CYA level up to 30 ppm on the same day I clean, refill, and balance the pH?

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Yes, you can certainly do that. Just note that pure CYA dissolves very slowly so could take a few days to show up in the test kit, though perhaps at the higher water temperature it will dissolve more quickly. Technically, you'll be getting more consistent disinfection and oxidation levels from day 1 (assuming at least some of it dissolves quickly) compared to Dichlor-then-bleach where the first days to week when using Dichlor start out at higher active chlorine levels and then decline to the steady-state level when you switch to bleach. This should be somewhat less harsh on hot tub covers, swimsuits, skin, etc. though it's not for very long relative to the time between water changes so not a big deal. The purpose of Dichlor-then-bleach is largely for simplicity since Dichlor dissolves so quickly and many people already have it if they were doing Dichlor-only previously.

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Good evening, good people! I'm AJ, brand new to the world of hot tubbing but I find the water chemistry aspects interesting. My wife has ordered a new Divine 440 GL spa and I'm doing some prep work to get prepared for what's coming in a few weeks. I've read, printed and highlighted NITRO'S Water Maintenance, I think that I'm going to enjoy this experience. However, I have a few questions.

1. When Nitro speaks about Dichlor is this in a liquid, granules or tablet form? Is their a preference? and is one manufacturer's chemicals preferred over another?

2. How thorough of a cleaning do you think is required on a brand new spa?

3. I read a lot of info on the site but I could not get a clear answer on how long will it take for me to get a spa usable after installation, because i know my wife and she is going to want to get in it as soon as the water is warm.

Thanks

AJ

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Dichlor comes as granular/powder. If you see chlorine tablets/pucks, then they are most likely Trichlor though could also be Cal-Hypo. As far as manufacturer is concerned, it doesn't matter so long as the ingredients are nearly pure Dichlor (check the label which should say 99% sodium dichloro-s-triazinetrione or 99% sodium dichloroisocyanurate which are synonyms for the same chemical).

A brand new spa has much more likelihood of having biofilms from the wet testing and has leftover grease from manufacturing. So a thorough cleaning using Spa System Flush (first) and then super-chlorination will have your first water fill last longer. Even so, the first fill may not last as long as subsequent fills since the cleaning process is not perfect.

The spa should be usable once you replace the water after the decontamination and then add some balancing chemicals -- 120-150 ppm CH, pH in the 7.5 to 7.8 range, TA in the 50-80 ppm range, 50 ppm Borates. If you are soaking right after this (after heating the water up), then just add around 2 ppm FC of Dichlor. Just note that this will be harsher during the first week until the CYA builds up from the Dichlor. If you want to avoid that you can add pure CYA to get to 30 ppm and just use bleach (i.e. skip the Dichlor).

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I hear a lot of people say they like the dichlor/bleach method but it's too needy. I do not have a tub yet and I like it! My question is what do you do to maintain spa when going on vacation for a couple of days or week. What is basic assortment of chemicals that one should have readily available.

Thanks

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Chlorine (dichlor/bleach) does require constant attention. Three step bromine (see Bromine for Beginners in the Spa water chemistry section of the forum) is more forgiving of being "ignored" for a week.

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As new spa owners, I went the weekly Dichlor shock, Mineral Sanitizer (Nature2) and MPS method replacing the water with each mineral sanitizer replacement (4 months, earlier refill as needed). The spa came with an ozonator though I haven't tested it. To reduce MPS consumption, I started using the dichlor (1/3 of the MPS amount) instead of MPS. I've since realized that this was overloading the cyanuric acid stabilizer level making the chlorine ineffective. I was also relying on inaccurate test strips for water balance measurements.

I've since bought the Taylor K-2006 for accurate measurement and have adopted the Dichlor/bleach method though without the Borates. I probably meant to add Borates but either overlooked it or didn't have a boric acid source and forgot about this step until re-reading the method summary. I'll probably add this back in going forward. I also overlooked adopting the Chlorine Demand measurement which I'll include going forward as well.

Using MPS messed with the combined chlorine measurement of test scripts I still had and was using for quick pre-entry measurement, so I quit using MPS. Without MPS, I didn't have to deal with alkalinity adjustments and we've rarely had heavy bather loads. I have MPS on hand and may buy the Deox Reagent for accurate MPS testing in the future.

Regardless of these omissions/changes, the dichlor/breach method has worked quite well and the water has been clear and well balanced (so long as the spa didn't go under treated on the rare occasion that I've been gone for a week).

My question is to what extent is continuing the mineral sanitizer (Nature2 Spa @ $65/yr) beneficial with the Dichlor/Bleach (or 3-step Bromine) method(s) since I have not been using MPS?

Thanks for the great info!

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The Nature2 silver ions don't have very much benefit with Dichlor/bleach. They may inhibit some uncontrolled bacterial growth if you let the chlorine get to zero, say on vacation, but there are other less expensive ways of handling that such as using some types of algaecides (linear quats, though they foam, or Polyquat which doesn't foam). These inhibit bacteria as well -- they just don't kill them quickly.

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Is ther a rule of thumb with how much bleach I need to add after soaking? The dichlor is measured aboved in your post as 3.5 tsp per person per hour. Any guidelines? How soon after adding do I check?

Thanks...

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The 3.5 tsp of dichlor per hour per person is for a 350 gal spa. 1 tso of dichlor will increase FC by about 7 ppm in 100 gallons and you want to add 7 ppm FC for each person for each hour they soak (so if two people soak for only 30 minutes you only need to ad 7 ppm FC. If one person soaks for 2 hours you would need to add 14 ppm FC)

Start with that amount and test the water a few minutes after adding and the next day. IF the FC is too low (below 2 ppm the next day) add more before you soak and use a bit more after the soak. If high (over say, 7-8 ppm) add less. Much depends on your usage patterns and whether you have ozone or not.

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Actually, the per person-hour amounts are independent of spa size because they depend only on the amount of bather waste. It's the 7 ppm FC reading that is only for 350 gallons; in a 700 gallon spa it would only be 3.5 ppm FC per person-hour. For every person-hour, it's around 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach (around 3-1/2 fluid ounces of the newer 8.25% bleach) or 7 teaspoons of 43% MPS (non-chlorine shock). This assume a hot (104ºF) spa and no ozonator or other supplemental oxidation systems.

As waterbear writes, what is important is that you add enough after your soak so that you have a measurable FC at the start of your next soak. You don't want FC to get to zero for an extended time.

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Is it better or more advantagious to use MPS some of the time and bleach some of the time, like alternating every day between the two? Or is it better to just stay with one or the other?

"Add MPS before/during high bather loads to help out the Chlorine, and keep CD low. (Optional but recommended)"

I'm trying to figure out how / what to use before bathing and what to add when we get out. I can see adding when you get out, but then there may be little to no FC. Do you add it about 30 minutes before you get in? Use the MPS before and bleach after?

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Bleach does a better job oxidizing some bather waste, but MPS is net acidic so if you are needing to add acid on occasion then you could alternate with MPS instead if you wanted to, but this will cost more than using just bleach.

You add oxidizer when you get out so that the next time you go in for a soak you have a low level of sanitizer, usually 1-2 ppm chlorine or 2-4 ppm bromine. That way, you minimize the smell during the soak. The only time you'd add more before your soak for a higher level would be if you were soaking with strangers and you wanted extra disinfection to prevent person-to-person transmission of disease. The fact that the chlorine/bromine gets used up in a soak with just your family members is not a problem because 1) there is monochloramine (for chlorine spas) or monobromamine (for bromine spas) formed that still kills bacteria, albeit slowly and 2) bacteria don't reproduce that much in one hour and you blast them with a lot of chlorine/bromine right after the soak thus preventing any biofilm formation. You can certainly target a higher disinfectant level at the start of your soak if you want to and see if you are OK with it, but most people prefer soaking with the lowest possible amount.

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Another question... We've been using the 3.5oz (8.25% bleach) rule as described above. We had another couple over Saturday night and we soaked for about 2hours so we put in 28 oz of bleach (340 gallon tub). I had the slighted ting of pink before I added this after our soaks. I also had teaspoons of MPS in the tub as well. Anyway - 12-16 hours later I still have 13ppm of chlorine in my tub...

Did I over do it?

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