Parrick

Thanks as always CG!

I have a question on this topic. Is monitoring TDS also a good way to determine the time to replace water? I have been operating off of the information that I found here (http://www.rhtubs.com/whentodrain.htm) for some time now. It has been my method to drain and refill when my TDS meter reads between 1000-2000 ppm TDS. We have a 1525 gal swim spa (with ozonator) which my wife uses, at most, every other day for about 20-30 minutes. When I run the numbers with the WRI formula I get: WRI= (1/3)x(1525)/(0.5)= 1016.67days = 2.79 years! I use the dichlor/bleach method. Water loss is replaced with water collected from dehumidifiers which is very low in TDS (essentially distilled water). I actually did let it go for over 2 years one time and the final TDS was 1124ppm. The water was behaving very well but I had to believe that 2 years was excessive. So, is TDS monitoring as described a reasonable alternative to the formula? Can I really go over 2 years without worry?

Interesting. I always appreciate your expert insight, Chem Geek. You are THE MAN around here! I have never had to lower my TA, just bump it up a bit on rare occasion, but as I recall the process is basically aerate, test, add acid, test, repeat. I also notice per the Pool Calculator that borates increase the amount of acid required to achieve the same pH drop. Seems like it would take a lot of time, testing & acid to counteract even a 20ppm TA increase. I think I will stick with the boric acid option. Is the "additional sodium chloride salt" significant? Is there a downside to the boric acid method?

Well the good news is that the boric acid did not affect my TA...I'm still dead on 50ppm. It did lower the pH by about 0.15

For a long time I have been reading about the benefits of borates so I decided to try it out. I had a 3LB can of Leisure Time pH Balance Plus on hand (97.98% boric acid, 2.02% sodium carbonate anhydrous) so I added that to my 1525 gal swim spa for 41ppm borates (per Pool Calculator). My intention was to use 16oz of 20 mule borax to bring the borate level to 50ppm. Out of curiosity I punched in 16oz of borax into the Pool Calculator to see what effects it would have & it said that that small amount would raise my TA by 20ppm!!! Is that correct? I run my TA at around 40-50ppm & have had good results with very slow upward pH drift in the past. Hopefully boric acid does not have the same dramatic effect on TA (Pool calculator does not have boric acid in the list for "Efects Of Adding Chemicals") Most of what I have read indicates that adding borates has a minimal effect on TA so now I am confused. Thank God I didn't use borax for the whole thing! That would have been 90oz of borax which the Calculator says would have raised my TA by 115! AM I MISSING SOMETHING? It would take a lot of work to counteract that much rise in TA!

Well after some more searching it looks like clear water with a slight bluish tint is good water. I don't have any brown, green or cloudiness so it looks like I don't really need to worry about metal issues. Hopefully I am on the right track because I'm planning to omit the metal chelation stuff altogether from here on out. I think I have answered my own question but any expert confirmation/input would still be appreciated!

I was wrong! I have a printout of the "Dichlor/Bleach Method In A Nutshell" thread in my reference folder and even highlighted the part about CYA dissipation. So much for my memory! But I'm getting off topic...

That's interesting. That's the first I have heard about the CYA dissipating. So what is the downside if your CYA reaches zero? Just increased chlorine consumption?

I guess the big question then is: Do I really need this stuff at all...either citric acid or phosphoric acid based? As I recall, both the dealer & the manufacturer recommended adding the Metal Gon during the fill process & I got the impression that it was very important. This is the last of the dealer-recommended concoctions that I still hang on to. I guess partly because they made it sound very important to the health & longevity of my spa and partly because I figured that it couldn't hurt. After all, it is only added once per fill & isn't that expensive. Now I am seeing information that only the phosphoric acid version is effective but that phosphoric acid may not be all that healthy to have in the water. Like I said before, the water appears to have a slight bluish tint but the spa is 4 ft deep & has a white bottom. Adding the chemicals (either version) doesn't seem to affect the bluish tint at all so I assume what I am seeing is not a metal problem anyway...just deep water. I have been searching topics but not finding much info on this stuff. Any insight would be appreciated.

I forget exactly what effect too much CYA has. You probably aren't too far out of range yet though. Plug your parameters into the Pool Calculator then go to the near bottom of the page on the Suggested Goal Levels row & select Traditional Spa. Go back up to the CYA row & it will show you what the suggested CYA level range would be for your application.

Additional Info: I did some checking & found that Spa Metal Free is a citric acid based product. From what I have read this is not the most effective chelating agent. I have always used Leisure Time Metal Gon in the past (phosphoric acid based). (Should have checked - pool store guy said it was the same thing) Now I am wondering if this product is going to have the desired effect & if I can or should add Metal Gon now? The water always has had a slight blue tint when viewed in sunlight (before & after application) but I have never had any staining issues that I have noticed. I have used Metal Gon in the past simply because the manufacturer recommends it at each new fill. The fill water is trucked-in city water & I don't know if I really need any of this stuff anyway. On the up side I notice that the Spa Metal Free bottle recommends adding a couple of ounces every week for "maintenance" so I assume that the citric acid dissipates over time & I probably don't have to worry too much about the over-application.

You switch from dichlor to bleach after you have gone through enough dichlor to leave behind the desired amount of CYA. The chlorine part of the dichlor "burns off" as it oxidizes contaminants (same as bleach) but the cyanuric acid (CYA) component is left behind & accumulates as you add dichlor. I use the Pool Calculator to do the calculations (www.poolcalculator.com). For instance, I am starting with a new fill (1525 gal) & I know I want my CYA level to end up at 20ppm. There is a section at the bottom of the Pool Calculator page, "Effects Of Adding Chemicals". If I enter 8oz of dichlor it indicates that that amount of dichlor will raise CYA by 20ppm. So I measure out 8 oz of dichlor in a separate container & use that as my sanitizer until it is used up. Then I know that I have accumulated 20ppm CYA in the water & I switch over to bleach. The Pool Calculator is a great tool to use to figure out how much of what to add & see what effect it is going to have. I know you have already started using dichlor in your water so at this point maybe you can weight what is left from the container & subtract from the label weight to determine how much you have used?

I have no idea about the Aqua Finesse. I stay away from most of the branded chemical concoctions. I have read too many horror stories on here where people have added brand X chemical to their spa or pool & the water turns purple & grows hair. I pretty much stick with the basic methods. The chemistry is tricky enough for me to understand without throwing in unknown variables. I got 2 years out of my last fill before the TDS got high enough for new water. That's with a 1500 gal swim spa with limited use (wife). One other thing occurred to me last night that you might consider. If you are currently shocking your water or have a high sanitizer level it can throw off the Taylor pH test & give false high readings. Just something to consider.

The CYA test is not worth the money in my opinion...very tricky to read accurately. Pretty much the whole TA vs pH thing boils down to this: 1) Check TA. 2) Add baking soda to raise TA to where you want it (This inherently raises pH) 3) Check pH. 4) Add dry acid to lower pH to where you want it (This reduces TA somewhat) 5) Repeat until both remain at the desired level They both work against each other but not at the same rate. Eventually you get to where you want to be on both. It made me nuts at first until I got the hang of it. After you reach the initial balance the TA will maintain pretty well. If it becomes necessary to raise your pH for any reason just use the aerators on the spa. Chemical "pH Up" products or additional baking soda will throw the whole balance off.

Kind of sounds like your TA readings are off. If the pH is drifting up that quickly it suggests that your TA is too high. (I assume that you have the aerators turned off while you are not in the spa) Are you using test strips? The ones I tried were horribly inaccurate - especially for TA. If you are using test strips throw them out & get a good Taylor test kit like the K2006. Nitro's thread was (and is) one of the best resources I have found. My daily spa maintenance kit contains a Taylor K2006 kit, Clorox bleach, dry acid (sodium bisulfate) & baking soda. I rarely need anything else except Dichlor & metal sequestrant when starting with new water. Dichlor has little effect on pH & TA except that it adds CYA (Cyanuric acid). CYA has a stabilizing effect on the sanitizer which helps protect from sanitizer depletion due to sunlight exposure. However, too much CYA is not good. So Dichlor is used as the sanitizer & tracked until the desired level of CYA is reached. Usually 20-40ppm. I aim for 20ppm because my spa is under cover & does not get much direct sunlight. The amount of Dichlor required to get to the desired CYA level can be calculated with the Pool Calculator (www.poolcalculator.com) Then you switch to bleach as the sanitizer because the CYA remains & does not deplete. I could go into a long explanation of the relationship between pH & TA but it has already been done in the threads you are reading. I think you are on the right track to throw in a little dry acid (Your Spa Down) and get your pH down to about 7.5 - 7.6 while you digest the rest of the info.

I would suggest reading all of the "pinned" threads at the top of this page first. Many of your questions will be answered in those threads and you will get a good heads up on the questions you will have in the future. Secondly, I would not do anything drastic to raise your TA just yet. Many of the experts on this forum suggest keeping your TA in the exact range you are at now. I keep my TA right in the same range (40-50) and it has greatly reduced the amount of acid I have to add to maintain pH. Now the pH creeps up very slowly and can take up to a week before I have to adjust it. If the spa gets much use, especially with the aerators on, it will need attention to bring the pH back down but if I know it hasn't been used I can get by skipping a day or two of testing & maybe just throw in a little bleach to be safe. Also, the less acid I have to add, the less TA drop I see so that's even less chemical being used.

I just did a refill on my swim spa. I had a brain flatulation and buggered up the calculation. I put in 25 oz of metal chelating agent when the correct amount would have been 15 oz. The chemical I am using is Spa Metal Free by Natural Chemistry. Is this going to be a problem?

Calcium Hardness Increaser (Calcium Chloride) available at any pool supply store. Use the Pool Calculator www.poolcalculator.com to determine the amount needed.

After reading some of the posts in the forum I learned that the "recommended" TA for my swim spa (80-150ppm) was way high & led to the need to constantly add acid to lower the pH. After some experimentation I found that a TA of 40ppm results in a very stable pH which will hold steady at 7.6 for up to a week or more. If the aerators are used it will creep up slowly & can easily be corrected with a small addition of dry acid. If I notice a trend in the pH creeping downward I know to test the TA & bump it back up a bit with some baking soda. This method has greatly reduced the amount of time & reagent that I use in maintaining chemistry. It is also nice to know that I can bump the FC up to 5 ppm or so & go on vacation for a few days without having to worry about the spa chemistry getting all out of whack & coming home to a disaster. My only concern is this: When I enter my numbers into the Pool Calculator I end up with a resulting CSI of -0.42. The Pool Calculator indicates that this has the "Potential to become corrosive to plaster". I am assuming that this is not an issue with an acrylic spa with stainless steel parts. Am I correct? Is there any downside to my method? My numbers are as follows: Size 1525 gal FC 3 pH 7.6 TA 40 CH 150 CYA 26 Salt 26 Borate 0 Temp 95 F CSI -0.42

Well, "fun" might be a bit of a stretch. I guess it is more about the challenge. I was never a "pool guy" but the wife developed a medical condition that led to us purchasing a swim spa to help with her therapy. That got me into the whole water-balancing project when the spa was delivered with the so-called "maintenance kit". It took about a day to figure out that test strips are better used as toothpicks. That led to this forum and a Taylor test kit. I had no idea that pool & spa maintenance was so involved but after studying the posts from yourself, Waterbear and the rest I got a pretty good handle on most of what I needed and avoided some pitfalls. This forum & its members are an invaluable resource! My failure was when I took it to the next level & bought a digital pH meter. When I noticed discrepancies between what I saw on the meter and the Taylor pH test that led to another meter to check against the first. It snowballed from there... Now my challenge is to figure out why 3 meters that are supposed to be accurate to within .01 sometimes show me a difference in reading by as much as .20 when they were all just calibrated. Okay, maybe I am having some fun but tools that don't work the way thay are supposed to make me nuts also. People use these things for purposes that require much more accuracy than what I am using them for so I have to assume that I am missing something. So THANKS VERY MUCH for the response, Richard! I greatly appreciate your knowlege! (and time) The base values you cite for CYA & FC are nearly identical to my own situation (no borates) so this should be very applicable information I will study the info you have provided and hopefully get a better understanding. Is the spreadsheet set up to work similar to the Pool Calculator? I wasn't able to get it working at first try. I think I have to enable macros or something. Thanks again, Richard! I have to dive in now... Patrick

Background first & then question at the bottom. I'm kind of a weirdo perfectionist by nature & I have a heck of a time reading the Taylor color-matching pH test. I think I am a bit color blind anyway. So I decided to go with a digital meter for pH readings. I have 4 of them now...that's right, FOUR! I started out with a Bluelab model with a gel-filled sealed probe but it was slow, only accurate to tenths & no temperature compensation. Then I got a couple of Milwaukee MW102 meters with temperature compensation & similar gel probes. These are supposed to be accurate to ± .01 but I found that spa water seems to be very effective at killing the gel-filled probes for some reason & they also began running excruciatingly slow. That led me to obtaining a couple lab grade glass refillable pH probes & yet another meter, an Oakton pH11 model with temp compensation & better features. The refillable probes give great response time (so far) and I am using one with the Oakton meter & one with one of the Milwaukee meters at the moment. I have been comparing all of the meters against each other and reference those results against my best guess with the Taylor test. (I even get the wife to look at the Taylor test also to get a 2nd opinion.) The results are usually close between all the testing methods but not good enough yet. The pH testing resources that I have studied indicate that the best results are obtained when the meters are calibrated with the pH buffer solutions held at the same temperature as the intended sample. Different meters & probes create varying levels of error the further they get from temperature that they were calibrated at. This is where I am getting into a dilemma. The spa temp is usually set around 98°F. Trying to heat the buffer solutions up to this level & maintain that temp through the calibration procedure is impractical. I have found that if I take a water sample from the spa & allow it to cool down to room temperature (The temp where meter calibration was done) that the different meter reading come much closer to consistent with each other. However, I also understand that temperature has an effect on the pH of a given solution (spa water). So here is the question: Does anyone know what effect temperature has on the actual pH of average spa water? In other words, if I measure my sample at 65°F how far off will my results be from the actual pH of the same water at spa temperature of 98°F? Most of the information that I have found on the subject indicates that the difference should be minor, maybe a tenth of a pH, but I haven't found any good reference to pool/spa water in particular. Pool water seems to be unique in certain characteristics. I still can't figure out why a general use, gel-filled sealed pH probe that stabilizes quickly in pH buffer would begin to respond so slowly in spa water. Distilled water does that but I wouldn't think that spa water would be anywhere close to pure water (or particularly harsh on a pH probe)...but that is a whole other topic. Sorry about the long post, Patrick

Thanks Waterbear! That is exactly the answer I was looking for! Easily 75% of the forum threads that I have printed out for reference have your name on them somewhere. I hope that you never get tired of helping the newbies! -Patrick

I have been studying this forum and other resources intensely for about 2 weeks now. I started out knowing nothing about water chemistry but now I think I have a fairly decent handle on the basics. Thank you so much to all the regular contributors on this forum! You have ben an absolutely INVALUABLE resource! There is one concept which I cannot seem to fully grasp. Here is what I (think) I know: 1) PH in a spa can be raised by aeration. 2) Aeration creates this effect by introducing carbon dioxide from the air into the water similar to the carbonation of soda. 3) So if the spa is in use for a period of time with the aerators on the PH will rise. 4) If the spa has been in use and I test the water afterwards I can expect to see that the PH has risen. So here is the question: Assuming that the spa has been in use for a period of time and the PH now reads higher than 7.8 Is the PH rise from aeration a fairly lasting effect which should then be corrected with the addition of acid? OR Is the PH rise a temporary effect which will correct itself after the aeration has stopped?