Water Test Results - Can One Of Our Experts Take A Look?

[ieremia]

Okay, just got by Taylor kit in the mail yesterday and did all of the tests. They were all pretty easy except for the last one that tests for Cyanuric Acid (I just didn't get the whole black dot thing). Anyway, here are the results:

Ph: 7.2

Free Cl: 8.5ppm

Comb. Cl: 3ppm

TA: 50ppm

CH: 160ppm

CYA: 60ppm

Water was at 98F when the test was taken. The water is about 10 days old. Can one of our resident gurus please tell me what they think of these numbers, pretty please? As of right now, the only thing I have a slight clue about is the PH but even that doesn't mean much to me. I bought the kit because you guys said it was a must have so now I need to know what it all means.

Thanks in advance...

Brian

EDIT: Forgot to mention the tub holds 480 gallons of water. I would estimate I have about 450-470 gallons in on average.

[chem geek]

Brian,

Your numbers look pretty good except that the TA is low. However, that low TA will help you keep your pH from rising as quickly so we only want to adjust that a little. I suggest that you add 0.5 ounces weight (about 1 teaspoon) of pH Up (sodium carbonate / soda ash / washing soda) which will raise your pH to 7.5 and your TA to around 60.

I assume you do not have any exposed grout in tile (or plaster/gunite); otherwise, you would need to get the Calcium Hardness higher.

The CYA is already high so don't use any Dichlor since that increases CYA. Instead, switch to bleach.

Your combined chlorine is rather high and probably indicates that you haven't been using a regular weekly dose of non-chlorine shock (potassium monopersulfate), is that right? If there is any way to expose your hot tub water to sunlight, then that will help break down the combined chlorine (CC). Otherwise, you can try the non-chlorine shock, but that's better at preventing the CC than eliminating them. You should start using the non-chlorine shock on a weekly basis regardless.

In the future when you do your tests, see if you can let the water sample cool closer to room temperature since most tests are designed to be closer to 75F or so. It's not a big deal, but will help you get more consistent readings that are a little more accurate.

As for explaining what is being measured, here is my take:

FC: this is Free Chlorine and measures the potentially active form of chlorine including that bound to CYA. That is, this is the amount of disinfecting chlorine plus the amount of chlorine "in reserve" (most of it is in reserve and bound to CYA).

CC: this is Combined Chlorine which is chlorine that has combined with organic compounds, but has not completely oxidized such compounds. This chlorine is not effective and not in reserve. It is used up, but can smell and you want to try and keep this CC number close to 0 (at least < 0.5). Sunlight helps to breakdown CC turning it into chloride ion (i.e. part of salt). Non-chlorine shock will oxidize organics before chlorine gets a chance to so will prevent CCs from forming.

pH: measures acidity vs. basic/alkalinity. 7.0 is neutral and the pH of human tears is close to 7.5 so that is typically the target that is used. Generally, you don't want to go below 7.0 since that is more corrosive to metal. Going up to around 8.0 is usually OK, but much higher and this affects the eyes.

TA: this is Total Alkalinity which is mostly the amount of carbonate in the water that is used to help buffer pH -- that is, it is a measure of how resistant the water is to changes in pH. Generally, this shouldn't be any lower than 50 when the CYA is at 30 or so. Traditional recommendations are for 80-120 depending on the source of chlorine (80-100 for hypochlorite; 100-120 for acidic sources such as Trichlor), but lower TA helps prevent a rise in pH and 50 is enough buffering if you use bleach or Cal-Hypo. At your CYA level of 60, I wouldn't have the TA below 60.

CH: this is Calcium Hardness which measures the amount of calcium. The combination of calcium (CH) and carbonate (TA and pH) needs to be at saturation levels if the water is in contact with any plaster/gunite/grout, but most hot tubs aren't in that situation and don't need as much CH. One source of chlorine, Cal-Hypo (calcium hypochlorite), adds to CH as well as FC (for every 1 ppm FC you get 0.7 ppm CH).

CYA: this is Cyanuric Acid which protects chlorine from breakdown from sunlight, but also reduces chlorine effectiveness. In a hot tub, you want some so that the chlorine isn't so strong, but not too much or else the chlorine won't be effective enough to kill the bacteria that causes hot tub itch (that's the only common pathogen that isn't super-easy to kill with far lower chlorine levels). Some sources of chlorine, namely Dichlor and Trichlor, add to CYA as well as FC (for every 1 ppm FC from Dichlor you get 0.9 ppm CYA and from Trichlor you get 0.6 ppm CYA).

Hope that helps.

[ieremia]

Mr. Geek,

Where do I begin...well, I guess I could begin by saying THANK YOU! I am amazed at the amount of insight you and a few others on this forum give out on a daily basis. I truly am grateful to have such great expertise here to assist with my lack of experience in this area of water upkeep.

My biggest question relates to switching to bleach. So far I was just using the CL granules that you can buy from Home Depot. Is there a benefit to using bleach other than cost? I like the granules because they are easy to use (and I have a big jar of it already). What would a good regimen be for administering the bleach? Daily, weekly, before use, after use?

As for adjusting the PH, is it okay to use the "Spa Up"/"Spa Down" products available at the big-box stores? I know a lot of you experts use certain common household products but again, I like the convenience of using the nicely packaged granulated forms in the neat little plastic jars. I know eventually I'll wise up and switch to the other stuff but I wanted to know if they will do as good a job as the common household products.

Once again, thank you for all of your wisdom. You are truly an asset to this forum!

Brian.

[chem geek]

Brian,

First of all, your welcome, and you need to understand that what I wrote was the cumulative knowledge of many people. I knew nothing when I started with my own pool years ago and have learned from others plus my chemistry analysis. This is a group effort and we're all here to help each other.

I have nothing against pool store products and use chlorinating liquid and pH Up from my pool store. I do so for the convenience even though it is more expensive -- I don't use that many chemicals anyway (except for chlorine and I like having the bottles "reused"). I just want people to know they have alternatives. The Spa Up and Down products are probably just fine. If you have a concern, let me know the specific product brand name (company and product name) and I can look up the MSDS if available just to be sure it doesn't have something "extra" you don't want or need.

Can you be more specific about the chlorine granules from Home Depot? If they are Cal-Hypo or say calcium hypochlorite, then that's OK to use as it will just increase your CH over time, but not that quickly. However, I suspect that these granules are Dichlor and may say "Dichloro-s-triazinetrione" or "sodium dichloroisocyanurate" or something like that and it is this Dichlor that you should NOT use any more of.

Richard (chem geek)

[Johnny D]

Thanks Chem Geek. So many more of read and gain knowledge. Appreciate you and others who take the time.

[waterbear]

If you are using a non chlorine shock disregard the combined chlorine reading. Non chlorine shock residual in the water will test as combined chlorine, even though it is not. Taylor sell a special reagent to remove this interferance if you are using non chlorine shock, but IMHO, it is not really necesssary as long as you add the non chlorine shock on a regular basis to maintain the residual and do not mix shocking with chlorine and non chlorine shock. Choose one method or the other. If you are using chlorine to shock then you need to shock to a much higher level than you have to reach breakpoint (at least 30 ppm in your case!).

[chem geek]

Thanks for the reminder about the non-chlorine shock showing up as CCs. I keep forgetting that and I don't know why. The monopersulfate (MPS) removal test kit is Taylor K-2041 here, but as was said you don't really need it since having residual MPS in the water ensures you won't have real (i.e. chlorinated organic) CCs. So if you've been using non-chlorine shock, don't worry about the CCs.

[Kushina]

I’m confused and can use some direction. We recently brought a 2007 Envoy that is equipped with an ozonater, N2 cartridge, and holds 450 gallons. Our dealer set us up and got us going with balanced water…I assume. The dealer suggested we use 1 tbsp of MPS after each soak and an ounce of dichlor a week to shock. Through this site I’m taking a crash course on proper water balance and maintenance, thus brought the Taylor K-2006. My first reading was TA – 50ppm, PH – 7.4, CH 220. I attempted to bring my TA up and the next thing I know my readings are TA 130, PH at least 8.0, and CH 250. Working Saturday & most of Sunday to get the water balanced and a chlorine reserve and weekly MPS shock, my readings at the end of Sunday were …TA – 90ppm, PH – 7.6, CH 240, FC – 6.2 (I added a lot of dichlor with hopes of some left over until the next day), CC - .6, CYA 45 ppm.

It’s been days and I wanna soak! Therefore, I tested once more this morning and I have…TA 90 ppm, PH 7.4, CH 250ppm, CYA 50 ppm, FC 2.2 ppm, CC .8ppm. Please note I also have a hard time maintaining chlorine until the next day.

With a FC of 2.2ppm and a CC of .8ppm, is there something ugly festering in water? Is this a false CC reading due to MPS? What’s considered too high on CYA reading? How much MPS do you recommend weekly? How much dichlor do I add to maintain a residual of 3 – 5 ppm? What do you think of my latest water test numbers? I think I tried to fix too much at one time and now I’m confused. Please guide.

[chem geek]

Your CYA of 50 ppm is OK, but I would switch to using unscented bleach (Clorox Regular or off-brand Ultra or if you can't stand bleach then use Lithium Hypochlorite powder/granules). I suspect the CC measurement is from the MPS and wouldn't worry about it. Your dealer is saying to use MPS daily but Dichlor (chlorine) only once a week but that will not sanitize your spa unless you have some chlorine most of the time (at least every day). The N2 cartridge helps, but the silver ion from it won't kill bacteria quickly -- it only does so slowly. The ozonator only kills pathogens that circulate through it but does nothing about those stuck in biofilms on spa surfaces nor newly introduced pathogens. Overall though, an ozonator plus N2 makes the risk low, but not as low as having a residual of sanitizer (chlorine, bromine, biguanide/Baqua/PHMB) which is why the EPA requires having a residual of one of those 3 at all times in order for products to be deemed effective sanitizers.

I would reverse what you are doing and add the chlorine bleach every day after you get out of the tub and use MPS once a week (if at all). The chlorine will only last about a day and that's normal, but it's inexpensive and easy to add. Either that, or you could add both bleach and MPS every day when you get out, but you might get some skin irritation if you do that (but probably would have had that by now if you were sensitive to MPS). You want to add enough chlorine to have it be low but not zero when you next get in. Usually that's around 3 fluid ounces in 350 gallons to add 4 ppm FC, but if you add the MPS daily instead of weekly you may find you need less chlorine. As for how much MPS to add, Dupont recommends 1-2 ounces per 250 gallons but that seems high to me. If you add it every day, I'd just add a tablespoon and see how that goes. If you add it once a week, then adding one tablespoon per person-hour might be the right amount, but your first soaks the next days might be irritating. If you find the CC climbing each week, then you're adding too much MPS (as it generally measures as CC). And you could just try using bleach after each soak and skip the MPS altogether -- with your ozonator and proper chlorine dosing you shouldn't be building up real CC.

Your ozonator may be breaking down chlorine which makes it harder to maintain, but you've got a higher CYA level of 50 which may help reduce this loss so let us know how things go as we're all just trying to figure out an optimum routine together. Personally, I like to use the least amount of chemicals and methods possible and optimize them to be effective so in my pool I use only chlorinating liquid and have a stable pH, CYA and other levels. No algaecides, no phosphate remover, no mineral cartridges, no non-chlorine shock, etc. A spa is more difficult due to the higher bather load, but you can still find an optimum routine.

With your numbers right now, go ahead and soak and enjoy your tub, then add some bleach when you get out and leave the cover off for a short time (10 minutes would be good; a half hour would be better, but might get the water too cold).

Richard

[Kushina]

Thank you for your insight, I will go take a nice long soak before night’s end. About 2 weeks ago, I did switch to using dichlor daily and MPS weekly after researching this sight and have thought of switching to bleach in the future. With the hot tub purchase the dealer included 4 lbs of MPS (potassium peroxymonusulfate 32.18%) and 3 lbs of dichlor (55% available chlorine), decent size bottles of spa up & down, large bottle of calcium hardness decreaser, test strips, and defoamer – all HS Fresh Water Products. We also have $170 credit toward future chemical purchases. That said I was hoping to use what we have and the credit received, as well as, learn more about water chemistry before making the transition to using bleach.

At the most two soak daily. Is there a calculation I can use to figure out how much dichlor to use daily to ensure proper sanitation and the recommended residual the next day? What’s considered too high on CYA reading? How much MPS do you recommend weekly in a 450-gallon tub? Do you recommend I also use the Taylor K-2041 with this water treatment routine? I guess - I’m asking if I’m on the right track while trying to figure out an optimum routine, before it get’s too cold in CT. to drain & start again.

[chem geek]

Thank you for your insight, I will go take a nice long soak before night’s end. About 2 weeks ago, I did switch to using dichlor daily and MPS weekly after researching this sight and have thought of switching to bleach in the future. With the hot tub purchase the dealer included 4 lbs of MPS (potassium peroxymonusulfate 32.18%) and 3 lbs of dichlor (55% available chlorine), decent size bottles of spa up & down, large bottle of calcium hardness decreaser, test strips, and defoamer – all HS Fresh Water Products. We also have $170 credit toward future chemical purchases. That said I was hoping to use what we have and the credit received, as well as, learn more about water chemistry before making the transition to using bleach.

At the most two soak daily. Is there a calculation I can use to figure out how much dichlor to use daily to ensure proper sanitation and the recommended residual the next day? What’s considered too high on CYA reading? How much MPS do you recommend weekly in a 450-gallon tub? Do you recommend I also use the Taylor K-2041 with this water treatment routine? I guess - I’m asking if I’m on the right track while trying to figure out an optimum routine, before it get’s too cold in CT. to drain & start again.

First of all, enjoy your tub -- that's more important than sweating (pun intended) about the chemistry.

There isn't a direct calculation that works perfectly because people introduce different amounts of organics (mostly sweat) into a spa. It does seem that if only using chlorine to oxidize ammonia that around 3-4 ppm FC in 350 gallons gets used up between 24 hours and one usage with one person for under an hour. I don't think this scales linearly since some loss, perhaps up to half, occurs even without usage so the rest, perhaps 1-2 ppm FC is a per person-soak amount. So maybe your soaking twice has a little more usage, but again that's something you can just see by adding chlorine when you get out and measuring it before you next get in (both the same day and the next day to get some sense for it). Once you roughly get things figured out, things will be much, much simpler as you'll just have a basic routine that you will do.

As for the large amount of chemicals you were given, I don't know what to say. The MPS could be used more frequently if you tolerate it, but the Dichlor will only end up increasing your CYA levels and does so rather quickly. For every 10 ppm FC added by Dichlor, it also adds 9 ppm to CYA. Since you've got both N2 and an ozonator, you could take a risk and just use Dichlor until the next refill, but may see some of the problems others have seen regarding a buildup of CC (though using MPS regularly should minimize or eliminate "real" CC and instead the CC will be showing the MPS level). The spa also won't be as disinfected, but again since you've got the ozonator and N2 it's a little less of a risk. Remember that many, many spa users used the Vermonter/Northman method with Dichlor-only usage even though after 3 months their CYA levels reached well over 200 ppm or even 300 ppm. I personally don't like such high CYA levels and technically a CYA level of 200 ppm will lower the disinfecting chlorine level compared to a CYA level of 50 ppm by around a factor of 4 and compared to a CYA of 20 it's a factor of 10. The main risk would be that of hot tub itch as most other bacteria are very easy to kill. I'm sorry I can't give you a definitive answer -- there isn't one -- it's all about probability and risk. It was the reports of hot tub itch on this forum that got me researching its kill times with chlorine and coming up with an FC and CYA recommendation.

As far as the Taylor K-2041 to supplement the Taylor K-2006 to get rid of the MPS interference in the chlorine test, that's up to you. If you plan on using MPS regularly, especially daily, then it would probably make sense to do, though waterbear's advice in this post is valid in that regular use of MPS can let you ignore the CC measurement (so the K-2041 is more for definitely knowing what is going on and isn't "necessary"). Again, I think you'll have a flurry of measurements for perhaps a week until you get a decent sense of how the levels go and then after that you'll just stick to your routine and not worry about measuring so often. The point is to enjoy your hot tub, not to be driven by its chemistry.

Richard