TA for a SWG pool

[ThePoolNinja]

Split off of this topic and moved to The Deep End. JasonLion

Depending on how many gallons your pool is, and the quality of the Conditioner you're adding, you may need to keep adding CYA until it gets up to 60-70ppm. Keep checking it and add by the LB accordingly.

A good place to keep your TA is between 100-120ppm.

Glad to see someone not afraid/too cheap to run their equipment!

 

[JasonLion]

Re: Need advice on my numbers

With a SWG, TA around 100-120 is going to cause PH to rise constantly, and require adding lots of acid. TA around 60 or 70 is much better.

 

[ThePoolNinja]

Re: Need advice on my numbers

TA around 60-70 is too low in my book, but to each their own!

 

[ThePoolNinja]

Re: Need advice on my numbers

crossnelson's PH is at 7.0, and TA at 140 at his latest update. Imagine if your TA is as low as 60-70, that PH may wander off into the danger zone. I've taken over so many pools where the previous homeowner or pool guy stripped the plumbing and stained the pool, and the TA was always below 80, and PH was far too low.

Either get ready to bust out the Soda Ash, or keep your TA around 100 and add muratic acid once in a while as needed.

 

[JasonLion]

With a SWG, TA around 100-120 is going to cause PH to rise constantly. Simple fact, try it and see. The usual result in a plaster pool is constant acid additions, eventually followed by a couple of days of inattention possibly leading to calcium scaling (quite expensive to remove).

We hear from hundreds of people with pools with a SWG and TA around 60-80. There have been essentially zero problems. And there are thousands more who don't bother to post because nothing is going wrong. The people with low TA and low PH are invariably people using trichlor and/or dichlor.

When you get the TA right (ie low enough) with a SWG pool, it just kind of "locks in", as most people describe it, and becomes stable. Raise the TA a little and PH goes up, acid needs to be added regularly and frustration follows.

You need to distinguish the pools with SWG from the ones using trichlor. The chemical recommendations are totally different, because the behavior of the pools is totally different. When using trichlor, TA around 100-120 is even a little too low. CYA behaves totally differently, everything is different.

crossnelson's PH is at 7.0 specifically because he is trying to lower TA, quite successfully by the by. Once he gets his TA in range we recommend PH between 7.5 and 7.8. There is no danger and no need for soda ash because there is no trichlor involved, and the PH is going to go up if it goes anywhere.

 

[chem geek]

When using a hypochlorite source of chlorine or when using a saltwater chlorine generator one hardly ever finds the pH to drop or get too low. As Jason said, it's the use of Trichlor pucks which are very acidic (especially when accounting for chlorine usage/consumption) where a higher TA is required to prevent the pH from dropping and to provide more buffering.

We've had some people with TA as low as 50 ppm, though 70 ppm is the more usual norm. With the somewhat lower TA, a higher Calcium Hardness (CH) target or pH target (around 7.7) can be used to compensate for the saturation index to protect plaster surfaces. A low TA is particularly necessary in spas using the Dichlor-then-bleach approach since the extra aeration and higher water temperature in the spa leads to more carbon dioxide outgassing that causes the pH to rise. One typically uses 50 ppm Borates with the Dichlor-then-bleach method.

Pools and spas are intentionally over-carbonated so will naturally have the pH rise if the TA is too high unless some form of acid is added, such as Trichlor or Dichlor since the usage/consumption of chlorine is acidic (so Dichlor is not really pH neutral when accounting for such usage/consumption). The amount of such over-carbonation is shown in this table.

 

[madwil]

My TA is 40, and pH holding rock solid at 7.4 for about 3 weeks now...
Expect it (pH, not TA) to go up slightly as it warms, and bather load increases!
plan on adding borates as additional pH buffer during the summer.

 

[rcy]

Usually, I'm completely lost when reading posts in the Deep End, but in this case I can actually chime in.

Starting my fifth season with and inground salt water pool. For three years, I followed the pool store suggestions and kept TA around 100 and was continually adding "PH down" powder (and then muriatic acid after I found this website) as PH kept climbing to eight and above. Last year, I tried to keep my TA around 80 and, lo and behold, my PH stopped climbing so quickly or so high - I don't think it hit eight once last year. I did have to occasionally add MA, but much less often than previously.

I'm thinking of aiming for 70 this year and see if the PH stabilizes instead of slooowly rising.

 

[maxepr1]

X2 on what Jason has said! I thought the same thing until I found this web site! Kept my TA around 110, always riding the PH roller coaster. Just thought was going to be the normal for SWG but just in the last month since lowering my TA (90 and going down) it is getting easier and more stable on the PH! Now I am rock solid at 7.2! Plus I have added the addition of Borates so I am hoping for a smooth ride this summer! Pool is allot more stable now. Holding FC longer now, not burning off as fast. Albeit no swimming as of yet but I finished shocking 13 days ago and I still have not turned my SWG on yet! Tested today and still will be several more days before I need to! This mornings reading was 13.5.

 

[gordiec]

X3 what Jason said. Once I got the TA of my SWG pool down to 70 the pH locks in at 7.6 for about 4 weeks before it starts creeping towards 7.8 (which is when I add muratic acid to bring it back to 7.6). I was adding acid weekly when the TA was at 120.