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.