Superchlorination With Bleach, Did I Do It Correctly?

[Nat]

I have a 330 gallon tub. My usual water care routine is 2 weeks of dichlor and then use 1/3 cup of bleach prior to spa use for the remaining 2 month fill. Weekly shocks using 4 tablespoons of MPS. I am 45 days into my tub fill. The water is not sparkiling like it used to be and I smell chlorine when using the spa.

This morning I tested chlorine levels with my Taylor kit. I got 0 ppm free chlorine and 1.4 ppm combined chlorine. So, I turned on the jets and slowly poured 1-1/2 cups of bleach into the water and let the jets run for 15 minutes with the cover off.

Is this enough bleach, given my readings? Should I still shock with 4 tablespoons MPS this weekend (tomorrow), or is the superchlorination adequate? When is it safe to go into the spa after superchlorination?

I take it that the MPS I have been shocking with does nothing to get rid of combined chlorine, but does get rid of oraganics in the water.

How often should superchlorination be used?

Thanks.

--Nate

[wireman]

I can tell you this. The chlorine smell is the CC's in your tub! Since I'm bored I'll throw in my 2 cents. I'd let the tub sit for a day. Test for FC and CC again. I'd wait for the FC to get down around 6 ppm and test for CC. For every 350 gals you can treat 1ppm CC with 1tsp MPS. I've been using that formula with a lot of success. So treat CC at that point. Wait 20-30 min and jump in!

[Nat]

I just tested the water (10 hours after superchlorinating) and I get 10 PPM free chlorine (which is what I tested it to be following the superchlorination). But oddly, I now measure 2.5 ppm combined chlorine.

Before I superchlorinated I measured 0.0 ppm free chlorine and 1.6 ppm combined chlorine. I can't see how combined chlorine would increase after superchlorinating. Something must be off with my testing.

Anyway, after dinner (in about an hour), I'm gonna soak. I guess I'll fine out what 10 ppm chlorine feels like.

--Nate

[wireman]

LOL! The chlorine you added reacted with organics in the water and created some more CC's . All you need to do is treat the CC's and let your chlorine level go down some.

[Woodsy]

Sounds like the organics need to be addressed a little more. Are you using any enzymes to break down the organics? If not, maybe something like Spa Perfect from Natural Chemistry or similar should be used regularly. Directions on the bottle are one ounce per one hundred gallons per week. So three ounces should suffice. If you use the spa a lot this should help out. Also, I usually suggest adding the MPS a little more often. Maybe twice a week.

[chem geek]

Nate,

One possibility for measuring positive CC is that it could be residual MPS (depending on how soon after you added the MPS you measure the CC) since that will interfere with the chlorine test unless you use an interference remover such as the Taylor K-2041 as shown here. However, given the timing of your tests and results, that doesn't seem likely. Since you smell a chlorine-like smell that isn't "clean" like bleach, it could be real CC (i.e. monochloramine) and that most likely comes from not using enough oxidizer or from the normal process of it hanging around for a while until it gets fully oxidized and this seems much more likely.

Let's first start with the question about quantity of bleach being used (and its concentration). 1/3rd of a cup of 6% bleach would yield 3.9 ppm FC in 330 gallons. This would probably be enough to oxidize the urea/ammonia from about 30 person-minutes of soaking (remember, this is rough and depends on the actual amount of sweat and sweat composition of the individuals doing the soaking). I know that this quantity was probably being used because of my 4 ppm FC and 20 ppm CYA recommendation, but what we've been figuring out since then is that it takes a LOT of oxidizer for typical spa usage. So if your spa usage is more than 30 minutes of one person, the amount of bleach or other oxidizer is probably not enough. The other thing is that you are adding it before you get into the spa which has the positive result of killing anything before you get in and during the first part of the soak preventing transmission of pathogens, but has the downside of having chlorine combine with your sweat while you are in the spa and that can smell of monochloramine as it doesn't get broken down immediately. This is the main reason some people only add a little chlorine before going in or add none and just add chlorine after they get out (hopefully with at least a small residual before they get in).

The weekly 4 tablespoons of MPS is equivalent to adding 12.3 ppm FC for oxidation. That would be enough for about 100 person-minutes of soaking. So we'd have to know how many people use your spa for how long each time and how many times per week (typically) to know if there's enough oxidizer (chlorine and MPS) being used -- and again this would just be a rough estimate.

Given the smell of chlorine and the CC measurement, I suspect that there's a buildup of monochloramine due to not enough oxidizer being used, but let us know your spa usage as that will help confirm or refute that suspicion.

As for the superchlorination, the good news is that having the FC not drop after 10 hours (which I find a bit unusual since there's usually some decline from outgassing if the temperature is kept high) would mean there's not more urea/ammonia because one thing that happens rather quickly, in under a minute, is for chlorine to combine with ammonia to form monochloramine (urea is also supposed to use up chlorine fairly quickly into a combined chlorine at high spa temperatures). It takes longer, around an hour at the lower CYA you are using, for the monochloramine to break down from more chlorine. As for MPS, it is not intended to be used "after the fact" to oxidize monochloramine, but Dupont says (in an E-mail to questions I had a while ago) that it probably does help oxidize such chloramine compounds (such as the CC that results from urea and chlorine). MPS works best if it is able to oxidize ammonia and urea (and other compounds) before chlorine gets a chance to combine with them, but for the simpler compounds from ammonia and urea and based on the experience in this forum, I think MPS can deal with this sort of CC very well.

10 ppm FC with say 25 ppm CYA will feel the same as 0.6 ppm FC with no CYA and that's far less than in most indoor pools and isn't particularly high so I doubt you'll notice much difference. It is about three times higher so will oxidize things (i.e. skin, hair) faster, but may not be enough to be noticeable.

Anyway, let us know your actual spa "person-hour" usage per day or per week and we can sort out what to do. I'm guessing more oxidizer is needed and we'll have to work out some appropriate combination of MPS and chlorine that works for you.

I'm not sure about the lack of water clarity, however. That is of a little more concern though that could just be other more complex organics (from skin oils or lotions) that aren't getting oxidized sufficiently. More MPS might help with that, but the suggestion of enzymes is a good one as well (they didn't work well for me in my pool, but they have worked well for others -- in my pool when a lot of suntan lotion was getting introduced, MPS turned out to clear it up better than anything else though historically higher levels of chlorine plus time and exposure to sunlight would take care of any oil film).

Nate, one other thing. Before trying the Dichlor then bleach method, did you use Dichlor only (i.e. Vermont/Northman method) in your spa in the past and if so what quantities did you use and did you also use MPS and if so how much? I assume you didn't have problems before so figuring out the total oxidizer level you used to have (assuming similar spa soak time and frequency) would be helpful.

Richard

[Nat]

Thank you for your replies.

As for the MPS possibly throwing off the chlorine readings, the last time I added MPS was one week before testing for chlorine.

I have been suspecting the bleach and MPS addition is on the low side for the spa use. My wife and I use the spa together, and soak 20 - 30 minutes every day, but soak twice on weekends, so the spa gets used 9 times a week, for about 4 hours total. So I guess that's about 8 person-hours per week.

Another thing that comes into play, and this has to have an effect, is that we are larger than the "average" person, so this has to tax the oxidizers (chlorine and MPS) more.

This is my second fill since purchasing the tub in October. I used Dichlor for about 2 weeks and measured about 45 ppm CYA right before I switched over to bleach.

I plan on testing the chlorine levels again today. We used the tub last night, with the 10 ppm chlorine and I did not add anything before soaking.

Maybe I could use 3 tablespoons of MPS twice weekly (instead of 4 Tbs. weekly) to get a little more oxidizer in the water. And increase the bleach a little, to 1/4 cup before using the spa and 1/4 cup added after using the spa (instead of just 1/3 cup before using the spa).

OK, I just edited my post to add the chlorine test results (Sunday morning, 24 hours after superchlorination):

Free chlorine is now 5 ppm and combined chlorine is 2 ppm. I even ran the jets for a minute or so to get a representative mix before pulling the sample.

Is the 2 ppm combined chlorine an issue, and if so, how should it be lowered?

Thanks.

Nate

[chem geek]

When you get a measurement of 2 ppm Combined Chlorine, how long has it been since you were in the tub? If it wasn't at least several hours, then I would expect to see some Combined Chlorine as it takes time to break down (when FC is present, then soaking in the tub produces CC and it takes time for the FC to oxidize it and lower the CC back down to zero). The tub should remain uncovered after you get out of the tub for a bit so the chemical process can get its gaseous products removed. If I read your post correctly, it's been about 8 hours since you used the tub last night and measured this morning, right? In that case, the CC is probably not monochloramine. Try some MPS to see if gets rid of it, but then that will interfere with future CC tests (a catch-22 unless you get the MPS test kit interference remover). If not, then it may be some persistent CC and perhaps the only way to prevent it in the future is with less chlorine and more MPS, but that's a guess on my part.

Most combined chorines are actually not harmful, but some are (most of the bad ones are volatile and what you have doesn't seem volatile -- if you air it out and it doesn't drop, then it's not volatile), and since there aren't simple tests distinguishing between them commercial/public standards require low CC. I doubt very much that the CC you are seeing are harmful, but it would be good to figure out why you are seeing them. I know that "traditional" pool folklore says that if you don't have enough chlorine to oxidize ammonia/urea that CCs will form and this is true, but they shouldn't be persistent and should be able to be removed with more chlorine or other oxidizer. Some folklore says that the process will get "stuck" if you don't have enough chlorine, so maybe there is something about that which is true. By any chance, do you use any lotions, makeup, or anything else organic (other than normal sweat and body oil) that might be getting into the tub? I read somewhere that certain types of organics can interfere with the breakpoint (oxidation of ammonia/urea) process so that's part of the reason why I'm asking.

Richard

[mck75]

"Try some MPS to see if gets rid of it, but then that will interfere with future CC tests (a catch-22 unless you get the MPS test kit interference remover). "

Excuse me for jumping in here, but I am interested in the persistent CC issue and was thinking of ordering the MPS test kit. How does it work, you do a titration, come up with a ppm number and then subtract that from the CC measurement to get a corrected CC?

Thanks, Rebecca

[Chris W]

I have the interference remover reagents and if my experience is typical, don't waste your time with it. The DPD and FAS-DPD tests are still completely un-believable for days after using a decent dose of MPS. You can find the instructions on how to use the remover with both FAS-DPD and DPD on the Taylor site.

http://www.taylortechnologies.com/products...amp;Number=5807

For Example: A week ago I was testing 4 ppm FC and 2 ppm CC after my daughter and her friends used the spa and it foamed up from the junk they got in the tub. Yes I did make all of them take showers without soap before getting in, but (I've decided that short of an hour in the pool, there's no way to get all the soap and lotion off of 12 and 13 yo girls The spa was crystal clear, just lots of bubbles. I hit it with a strong dose of MPS and after a day or so put in a clean filter. I maintained a continuous chlorine residual all week. but still had 2.5-3 ppm CC a week later. Yesterday I opened the tub, turned on the jets with air for a while and let it sit exposed to UV for a while. It tested 3ppm FC, 2.5 ppm CC with or without the interference remover. Yesterday I hit it with about 7 or 8 oz of 85% MPS. After about 6 hours with the cover open most of the time and aeration on and off, it tested 7ppm FC (about 3ppm with OTO) and 2.5 ppm CC with or without the interference remover. I used the tub last night, but did not add Chlorine. This morning, it is testing (FAS-DPD) 20+ ppm FC, 2.5 ppm CC, interference remover makes no difference (OTO is dark yellow, but not orange) Based on my tests, I am producing FC and doing nothing to get rid of CC. I got the interference remover reagent at the local Leslies Pool store, I'm sure it's low volume item for them, maybe they are too old?

I think an indoor pool operator reported similar results on another forum when he tested MPS in a bucket to see if it could help with his CC situation.

It's worth noting that the entire time this was going on, the water was crystal clear, had no more chlrine smell than normal and did not cause any unusual irritation to my skin.

For what's it's cost in time, chemicals and testing supplies, I would have saved a ton of money and time if I had just drained and re-filled the spa after my daughter's friends were in the tub. I'm very frustrated trying to use MPS as there does not appear to be a good way to measure a residual after a shock and worse than that, it seems to destroy the ability to reliably test for proper sanitizer levels. The residual does not appear to dissapate like Chlorine, it appears to stay until enough organics have been introduced to consume it.

After I drain and re-fill, I may leave the MPS in the cupboard, use dichlor for a week or two and switch to chlorinating liquid and just shock with extra chlorine when CC shows up. At least if I leave the MPS out I know I can test reliably.

Chris W

[chem geek]

Thanks Chris. That's really good information to know. I have the interference remover, but since I hardly every use MPS (in my pool) I really could never verify if it was working properly. That means we still need to sort out the CC issue -- is it a real problem and if so how to resolve it. Whereas some reported seeing CC with Dichlor-only and that had a technical explanation, now we see some using bleach and having a similar issue so there's more going on than just a slower breakpoint. My hunch is that it's just an accumulation of more complex organics (oils, proteins, etc.) that have combined with chlorine. So *maybe* a good enzyme could help, but that's just a guess.

Let us know if anything gets rid of the CC for you, including shocking with chlorine. I suspect that for some CCs, exposure to sunlight will help, but that's not always an option for a spa/tub. And be sure to let us know how using chlorine and not MPS works for you. I wouldn't want to advice people to use MPS if it's going to make their FC and CC testing suspect.

Richard

[Chris W]

I've been tweaking my post so I may have added information after you replied.

I've got a bottle of Spa-Perfect, but I haven't used any in over a month. MPS destroys it so I'll have to wait at least a day or two to try it. I'm in AZ, so I can put sun on the spa this time of year dring the daytime without the eletric bill going crazy I'll try the enzymes in a few days and see if they help at all.

Chris W

[chem geek]

Nate,

How quickly did the CCs begin to appear? Was it a gradual increase and when did it start? Or was it all at once in which case what happened between the low and high CC readings?

If waterbear is reading this, any idea about the seemingly persistent CCs? Any thoughts about the MPS interference remover working or not? I recall we had a persistent CC report in an indoor pool at TroubleFreePool and pretty much nothing got rid of it in bucket tests. Not MPS, not UV light (from a tanning bed, though it did get rid of FC), not chlorine shocking, not airing out. The only thing that made it go away was adding a reducing agent (which really isn't different than what the R-0003 iodide is doing except it gets oxidized to iodine that then shows up in the CC test). I wonder if perhaps the R-0003 may be reporting some oxidizer other than Combined Chlorine (which is an oxidizer, at least relative to ioidide) and other than MPS so that it's essentially a false reading.

Richard

[Chris W]

A few days after my heavy shock with MPS, I still showed about 3+ppm of CC. After the test readings had come back within reach of reality, I used chlorinating liquid to take the spa to about 25-30 ppm FC. As the FC was coming down, the CC appeared to have dropped to about 1-1.5, but now that the FC is back below 10, the CC is reading 3+ again. By tomorrow I should have the FC low enough to let the enzymes have a run at it. If the enzymes don't do anything, I'll call off the experiment and drain and re-fill

The tub is still crystal clear, not at all unpleasant, and If I weren't testing with a good kit, I'd assume it was all perfect.

Time for a quick soak before bed

Chris W

[Chris W]

WOW! I just took a soak in my tub after coming down off a roughly 30 ppm Chlorine Shock. The water tested a few hours ago at 9 ppm FC and still over 3 ppm CC . That's nothing to brag about, but what really surprised me is that I just had the cleanest, clearest, freshest, soak in the entire time I've owned the tub with absolutely NO chemical smell whatsoever. It reminds me of the 1st time I swam in a SWG pool. This sets a new bar for my expectations of how good the tub can be and makes me more inclined to use smaller doses of MPS as a daily supplement rather than a shock and hit it hard with Chlorine periodically to really clean it up.

Chris W

[waterbear]

WOW! I just took a soak in my tub after coming down off a roughly 30 ppm Chlorine Shock. The water tested a few hours ago at 9 ppm FC and still over 3 ppm CC . That's nothing to brag about, but what really surprised me is that I just had the cleanest, clearest, freshest, soak in the entire time I've owned the tub with absolutely NO chemical smell whatsoever. It reminds me of the 1st time I swam in a SWG pool. This sets a new bar for my expectations of how good the tub can be and makes me more inclined to use smaller doses of MPS as a daily supplement rather than a shock and hit it hard with Chlorine periodically to really clean it up.

Chris W

No surprise to me. Perhaps if you forget the MPS, maintain your FC at about 4-5 ppm at all times and shock weekly with chlorine you will not have any persistant CC. Might be worth a try. (I've seen it work before). This doesn't mean letting the FC drop to 0 and then bumping it up. It means daily testing to maintain the level. If you are finding the level hard to maintain then I would suggest a spa purge on the next drain and refill to clean out the plumbing (The ezyyme based ones work well. follow with shocking to about 30 ppm FC.)

[waterbear]

WOW! I just took a soak in my tub after coming down off a roughly 30 ppm Chlorine Shock. The water tested a few hours ago at 9 ppm FC and still over 3 ppm CC . That's nothing to brag about, but what really surprised me is that I just had the cleanest, clearest, freshest, soak in the entire time I've owned the tub with absolutely NO chemical smell whatsoever. It reminds me of the 1st time I swam in a SWG pool. This sets a new bar for my expectations of how good the tub can be and makes me more inclined to use smaller doses of MPS as a daily supplement rather than a shock and hit it hard with Chlorine periodically to really clean it up.

Chris W

No surprise to me. Perhaps if you forget the MPS, maintain your FC at about 4-5 ppm at all times and shock weekly with chlorine you will not have any persistant CC. Might be worth a try. (I've seen it work before). This doesn't mean letting the FC drop to 0 and then bumping it up. It means daily testing to maintain the level. If you are finding the level hard to maintain then I would suggest a spa purge on the next drain and refill to clean out the plumbing (The ezyyme based ones work well. follow with shocking to about 30 ppm FC.)

[waterbear]

WOW! I just took a soak in my tub after coming down off a roughly 30 ppm Chlorine Shock. The water tested a few hours ago at 9 ppm FC and still over 3 ppm CC . That's nothing to brag about, but what really surprised me is that I just had the cleanest, clearest, freshest, soak in the entire time I've owned the tub with absolutely NO chemical smell whatsoever. It reminds me of the 1st time I swam in a SWG pool. This sets a new bar for my expectations of how good the tub can be and makes me more inclined to use smaller doses of MPS as a daily supplement rather than a shock and hit it hard with Chlorine periodically to really clean it up.

Chris W

No surprise to me. Perhaps if you forget the MPS, maintain your FC at about 4-5 ppm at all times and shock weekly with chlorine you will not have any persistant CC. Might be worth a try. (I've seen it work before). This doesn't mean letting the FC drop to 0 and then bumping it up. It means daily testing to maintain the level. If you are finding the level hard to maintain then I would suggest a spa purge treatment on the next drain and refill to clean out the plumbing, possibly a source of your persistant CC, although testing error is also a possiblility. (The ezyyme based ones work well. I've used the one by Natural Chemistry). Follow with shocking to about 30 ppm FC for good measure.)

One other thought, you are leaving the spa uncovered and the circulation running when you shock, aren't you? Do so until the FC is at normal levels and then test for CC. If the spa gets sunlight shock during the day so the sun can hit it, this also helps.

[chem geek]

WOW! I just took a soak in my tub after coming down off a roughly 30 ppm Chlorine Shock. The water tested a few hours ago at 9 ppm FC and still over 3 ppm CC . That's nothing to brag about, but what really surprised me is that I just had the cleanest, clearest, freshest, soak in the entire time I've owned the tub with absolutely NO chemical smell whatsoever. It reminds me of the 1st time I swam in a SWG pool. This sets a new bar for my expectations of how good the tub can be and makes me more inclined to use smaller doses of MPS as a daily supplement rather than a shock and hit it hard with Chlorine periodically to really clean it up.

Chris W

This just confirms my suspicion that most tub/spa users aren't using enough chlorine to keep up with the ammonia/urea demand from sweat. The chlorine smell comes from monochloramine (chlorine combined with ammonia) so if you don't keep up with oxidizing it then it will build up. As waterbear says, you need to keep the FC level up and/or shock with a lot of chlorine regularly to ensure you get rid of all ammonia/urea/monochloramine.

Technically speaking, if you measure an FC residual, then there cannot be any ammonia/urea in the water since chlorine combines with it very quickly so within one minute it's fully combined. However, the breakdown of monochloramine takes longer so the shocking with a higher level of chlorine helps to get rid of the last of it faster. Technically, this shouldn't be necessary if the FC level is kept up more continuously, but that's harder to do in a spa and maybe shocking with chlorine is needed for other reasons (to oxidize other organics more fully).

What is interesting is that you didn't have any smell during your soak since sweat should have combined with the chlorine so monochloramine should have been produced and it can smell. I doubt it was getting oxidized fast enough, but let us know your experience in the future since maybe you've hit upon a way for people to soak with chlorine (i.e. use enough to ensure at least some breakpoint) and not have the smell associated with monochloramine. What was your CYA level (you said the FC was 9 ppm)?

By the way, for your shocking, if your CYA was only 20 ppm, then a 30 ppm FC would be equivalent to 11.7 ppm FC with no CYA which is pretty high. If your CYA was 30 ppm, then 30 ppm FC is equivalent to 5.9 ppm FC with no CYA. If your CYA was 40 ppm, then 30 ppm FC is equivalent to 3 ppm FC with no CYA.

Richard

[Chris W]

My CYA is about 40, so the 30ppm FC didn't seem overly aggressive to me. The tub is a bit over 500 gallons, it was just me, and my soak was only about 15 minutes. This might explain the lack of monochloramine smell while in the water. The tub held a FC residual over night, but it was down to about 3 ppm this morning. While the sanitizer was down to a normal level, I added Spa Perfect enzyme to see what that would do with the CC number.

This afternoon there was decent amount of chloramine smell so I kicked on the air to drive out anything volitile. A while later I tested the Chlorine and I'll have to admit that I'm confused by the numbers. A quick check with OTO showed a TC just a tad darker than 1.0. I went on to FAS-DPD which showed 2.5 ppm FC and 4.5ppm CC, That's tough to believe and makes me question all of the readings I've reported thus far I tested with regular DPD next which showed a little lighter than 1 ppm FC and a bit lighter than 2 ppm TC. That test seems to support the OTO and lead me to believe that my FAS-DPD is off somehow. Maybe my R-0871 is bad, but it's fairly new so age shouldn't be the issue. It could have been frozen in the mail, does anyone know if that would mess up R-0871? I'll order some more either way. With all this testing I'm already running low and I just got 2 oz. over the holdays

After testing I brought the FC up to about 4 ppm for the evening soak. The tub is crystal clear and aeration seems to be clearing off the monochloromine smell. I have to agree with Water bear that higher Free Chlorine and Chlorine Shock may get me where I want to go.

When I get done playing with this maybe I'll just brek down and get myself a Spa-Pilot..... Except skip the MPS ritual they recommend and manully shock with Chlorine as needed.

Chris W

[waterbear]

This afternoon there was decent amount of chloramine smell so I kicked on the air to drive out anything volitile. A while later I tested the Chlorine and I'll have to admit that I'm confused by the numbers. A quick check with OTO showed a TC just a tad darker than 1.0. I went on to FAS-DPD which showed 2.5 ppm FC and 4.5ppm CC, That's tough to believe and makes me question all of the readings I've reported thus far I tested with regular DPD next which showed a little lighter than 1 ppm FC and a bit lighter than 2 ppm TC. That test seems to support the OTO and lead me to believe that my FAS-DPD is off somehow. Maybe my R-0871 is bad, but it's fairly new so age shouldn't be the issue. It could have been frozen in the mail, does anyone know if that would mess up R-0871? I'll order some more either way. With all this testing I'm already running low and I just got 2 oz. over the holdays

Chris W

A few thoughts....

When you tested with the OTO did you wait about 3-4 minutes before reading it? OTO only tests total chlorine and it can take a few minutes to fully develop.

As far as the discrepancy between the DPD test and the FAS-DPD test I have 2 possible explanations...

The first. At least 1 out of 5 men have a lot of difficulty determining the different shades of red on the DPD comparator (I assume you are male, your name could be either). Have a woman double check your test results readings.

The second is that the FAS-DPD titrant is prone to static electricity affecting the drop size and making the drops smaller so you get a (false) higher count. The remedy is to wipe the dropper tip with a damp tissure before you form each drop.

In theory you are supposed to do this for all drop based titration in plastic dropper bottles but it seems the FAS-DPD titration and the silver nitrate/chromate test for chloride (salt) are the most prone to static causing inaccurate results.

The first you can't to much about. The second is easy to check.

[Chris W]

Usually the OTO test sits for a few minutes before I pour it out, but it doesn't normally darken significantly. I'll try letting it sit.

I have been reading the DPD and PH tubes for years without percieving a problem, but I can ask the Wife to look at one too.

I've had more drop size issues with PS kit and TF kti bottles than with Taylor bottles. I'm using the bottle from TF that makes the bigger drops of the two I bought (they did produce different size drops) and I measured it to be very consistent to my original PS234 bottle, but I've never had a Taylor bottle of R-0871. I think my next bottle will be a C size from Taylor. Betwwen the pool and the spa, I use it quite a bit :-) I'll try the tissue trick too.

Thanks for the ideas.

To answer your earlier question, I do leave the cover open for several hours after a shock chlorine or MPS. I run the jets occaisionally and the circ pump run 24/7. I cover the spa at night and when I'm at work. I try to give it some sun on the weekends :-)

Chris W

[Chris W]

Well, I inadvertantly changed out over half my water the other day, so I can't commnet on the effect on the persistent combinrd chlorine that I seemed to be experiencing. But I'm about 3 days into a chlorine only routine using 12% chlorinating liquid and acid to maintain FC and pH.

The unplanned water change was simple distraction. Right after I put a hose in to top off the tub, my daughter started panicing over some files she thought she deleted from her computer. After addressing her issues, I wnadered back outside and rememberd the hose was running My tub slopes very slightly towards one corner, so the overflow was just gently rolling down the corner and across a foot of patio into the river rock drainage channel for my patio. No puddle, no mess, no damage, but I did hook up a hose to the drain and drop the tub back down to the highest level I normally run. Before the mistake I was measuring about 7ppm FC and 40 PPM CYA. After the incident I was measuring about 3 ppm FC and less than 20 ppm CYA. I guy this translates into a change of over 50% of my water. That should by me at least another month before I need to drain and refill :-) It's probably a topic for it's own thread, but it makes me wonder about the advantages and disadvantages of more frequent partial water changes like I do in my Aquariums.

I may use dichlor a time or two to get the CYA up to the 20-25 range, but for the most part, I'll just use liquid chlorine and acid to maintain the FC in the 4-7 ppm range and pH in 7.4-7.6 range. I'll shock with more Liquid if/when CC starts to build up and enjoy the fact that I can once again reliably test my FC and CC.

It is time to order more R-0871. I think this time I'll order straight from Taylor to get their bottle. I've never had trouble with the drop sizes with their bottles. The drops did get bigger on the TF bottles whaen I did the moist tissue wipe before every drop, but it about drove me crazy to stop and wipe the bottle every drop

Chris W

[waterbear]

Sorry to burst your bubble but the wiping the dropper tip info comes from the Taylor website! Their bottles (as do all plastic dropper bottles) suffer from the same problem. It really only seems to have a major effect on the FAS reagent and the sliver nitrate reagent used in the chloride (salt) test.

[Chris W]

Sorry to burst your bubble but the wiping the dropper tip info comes from the Taylor website! Their bottles (as do all plastic dropper bottles) suffer from the same problem. It really only seems to have a major effect on the FAS reagent and the sliver nitrate reagent used in the chloride (salt) test.

That's good info. Thanks. When I was using the tissue, the difference in the drop size was apparent on the 1st drop, but the drops didn't obviously get smaller if I did 2 or 3 drops, do you have ans sense of the practical number of drops that you can get before re-wiping without significantly impacting the test outcome?

I was disappointed to see that the online ordering from Taylor is currently hosed up. Their website is dangerous to my pool and spa budget, The more I dig around on their site, the more stuff I find that I want to buy. I saw that they sell standard solutions, presumable used to verify accuracy of testing technique. I'm temped to order some 50 ppm CYA solution just to see exactly what the proper endpoint is supposed to look like and then there's the salt standards that I could use to calibrate my Salt Meter. I suppose with a little math, some help from chem geek and much more accurate scale I could make that stuff myself. Then there's the test kit to test the strength of bleach..........

Chris W