Considering a SWCG. Thoughts?

[pjt]

what system would you recommend?

Do you have automation? I didn't see any in your signature.

 

[Newdude]

what system would you recommend?

We rec a 2X unit or more because a properly sized unit needs to run 24/7 to produce enough FC and may not keep up in the peak season if it's a warm year.

Going larger ensures you can produce enough FC when it's hot and also gives you flexibility with pump runtime. A 2X unit needs 12 hours or a 3X unit needs 8 hours.

Going larger also costs much less than the increase in lifespan so its like buying your next unit at a steep discount. For example a 20k to 40k unit has double the life for 20% more.

Units are depleted with runtime expecting between 8k and 10k hours 'on'. Your long TX season will use said hours sooner than my NY summer. Oversizing comes in handy again here. I would have gone 3X in a heartbeat if one was available.

Look at Pentair and Circupool. If you have automation as @pjt asked, then you need to stick with Pentair so it all talks to each other.

 

[Rick T]

No automation in my system. I have to manually move valves. just 2 timers, 1 for pool, 1 for Polaris.

 

[Rattus Suffocatus]

I actually am having more trouble with my SWCG than most people do, but even having said that, I think I would do it again.

I might pick a different model or unit. Circupool in the one time I dealt with them on warranty were very good, however. I figure they will be the second time too. I'm sure I'll be back up with a few hundred dollars spent in the spring for at least another 2.5 years.

It's one of these cases where it's so convenient that if you are going to "splurge" on any part of a pool, that is the most logical place to do it. I did a bunch of calculations back before crazy town inflation happened (you can search for them here), and it was a no brainer then. It kinda isn't now with the same calculations... but I got through several months of bad times with the minimal amount of work you need to do and still keep the pool TFP. It's worth it just for that! Really once you get to a cadence, all you usually need to do is add acid to the water. At least until your CH creeps up.. that might be the only issue really.. you can push that out farther on a non SWCG pool if you live in an area like me that there are more minerals in the water than water. A lot of acid... lots and lots....

But yeah. I dunno about automation. You only need to tweak the amount of chlorine generated maybe 3-4 times a season.. I guess if you need to have Alexa do it for you.. fine...I never begrudge anyone their toys, God knows I have enough of them, including some smart home stuff (I can turn the pool light on with Alexa...)... but I like the adjustment knob.. I really do... the smart stuff to me is dumb and it's getting worse and worse with all of the tech layoffs....

 

[Padle]

... but I got through several months of bad times with the minimal amount of work you need to do and still keep the pool TFP. It's worth it just for that! Really once you get to a cadence, all you usually need to do is add acid to the water. At least until your CH creeps up.. .

How does a SWG raise the CH?

 

[Padle]

My system is installed!

Cost

$1269 on universal 55
$50 on 320 pounds of salt from HD
$200 to handyman (I'm not handy)

I'll let y'all know how it goes.

 

[Padle]

Also, who has the power to add universal 55 to the pool math app and to the SWG profile options?

 

[PoolStored]

How does a SWG raise the CH?

It doesn't. CH will creep up if your fill water has CH and you don't get much rain. You should be fine.

Also, who has the power to add universal 55 to the pool math app and to the SWG profile options?

Use 2.9 for your 24 hr output.

 

[PoolStored]

I'll let y'all know how it goes.

Don't turn it on until the salt has dissolved AND you have circulated for 24 hours, and you TESTED salt. Do you have a K-1766 to test salt? TEST YOUR SALT BEFORE YOU ADD ANY...you likely have a bunch already in...

 

[Padle]

Don't turn it on until the salt has dissolved AND you have circulated for 24 hours, and you TESTED salt. Do you have a K-1766 to test salt? TEST YOUR SALT BEFORE YOU ADD ANY...you likely have a bunch already in...

Yup, did all that, I have the Taylor salt test, after adding all the salt, it came out to 3000 which is borderline for the SWG to work.

 

[Padle]

Can someone explain the rational why the target FC is different in a SWG vs LC. I mean does the CYA care how you are making your chlorine?

 

[mknauss]

Can someone explain the rational why the target FC is different in a SWG vs LC. I mean does the CYA care how you are making your chlorine?

Chlorine/CYA Chart

EDIT: You will find a simplified and standardized version of this chart at Pool School, Chlorine / CYA Chart. Chlorine/CYA Chart by Chemgeek FC = Free Chlorine in parts-per-million (ppm) CYA = Cyanuric Acid in parts-per-million (ppm) CYA ........... Min FC3 ..... Target FC ...... Yel/Mstrd...

www.troublefreepool.com

See Note 3.

 

[Padle]

Thanks! I also found this, which seems to cover a lot.

Ok, here is the original PM (including a quote from my original post at the end in bold)and my answer:

donaldm823 wrote:
Dear waterbear:
I read the following post from you saying you could explain why CYA must be in the 60ppm range for a SWG or cell failure would result. I just installed a Autopilot Digital and left my CYA at 30ppm since I only had a month left in my pool season. Since it ran so well in Sep , I was considering leaving CYA at 30ppm for my next pool season vice raising it to 60ppm so that I could keep my FC lower, use less Chlorox when shocking, and keep the algae at bay!.

Could you email with the tech explanation why I need the 60ppm CYA level? I thought the 60ppm was just so the SWG cell could run less time and give the chlorine a chance to mix with the pool before it was impacted by the sun. But your email (I quote below), implies something more sinister and alerted me that maybe I should be following the owners manual and accept a higher FC level. I have the SWG-60 which is rated for a 60,000gal pool (mine is 30,000). I also watch chemistry closely on a daily basis with my LaMotte ColorQ, so I keep pH in check.

Don

I know it's a bit late since you removed the SWG but I know why you had so many problems with it if your last water test is typical. Your stabilizer level is 30 ppm and that alone is enough to cause early cell failure and major pH problems leading to scaling and short cell life! This is why Goldline recommends a CYA of between 60-80 ppm. It's in your user's manual (you DID read the manual, right). If you would like a detailed explanation of why having too low a CYA level can cause cell failure and pH and scaling problems I would be happy to provide it but it is technical. What I am surprised at is that your local Pinch a Penny did not catch this! (Actually, I'm not that surprised. I work in the industry. )

Here is my answer to the PM:

Nothing sinister but just some basic science and water chemistry and an understanding of how a SWG works and interacts with the water chemistry. Having CYA in the recommened range allows the cell to maintain the FC at the desired level with a lower output percentage than if the CYA is too low. This has several ramifications.

The first and most obvious is that a lower output percentage directly translates into a longer cell life! (This is also an excellent reason NOT to use the boost or shock feature of a SWG but to shock with liquid chlorine instead but is not actually the BEST reason to do so. Without getting into the chemistry involved let's just say that using liquid chlorine and adding the full amount needed all at once is going to produce more efficient shocking than the gradual increase over a 24 hour period of FC by using the boost or shock function.) Cells are rated in hours of life and the less time it spends in the on state the longer it will last!

The second reason is also linked to output percentage. When the cell is generating chlorine it produces clorine gas at one electrode which dissolves in the water to form your active sanitizer, hypochlorous acid. Exactly the same as if you had added liquid chlorine. However, the other electrode is producing hydrogen gas bubbles. These aerate the water, which causes carbon dixoide to outgas (Your pool is overcarbonated, we call this Total Alkalinity!) The outgassing of carbon dixoide causes the pH to rise! (Carbon dioxide in water is basically, for our purposes here, carbonic acid -- think seltzer!--Shake it up and the carbon dioxide bubbles off and the seltzer turns to water--the carbonic acid disappears!) pH rise is a major problem with salt water genterators so by maintaining the proper CYA level in the water you can help minimize this pH rise and help reduce your acid consumption.

pH rise can be responisble to shortened cell life because pH rise is the ONE FACTOR that will predict scaling condition. High pH leads to scaling, period! ( I will not go through a lengthy explanation of the Langelier Saturation Index here but I have discussed this at length before at Poolforum. com. )
Scaling can shorten cell life if allowed to build up. Cleaning cells on a regular basis is a pain. Runing the proper CYA level helps slow scaling by allowing for a slower pH rise.

All these factors will contribute to a longer cell life and they are all accopmplised by running the CYA at the recommened level!

Now for a few more things to think about. The manuals for just about every SWG on the market recommend a FC between 1-3 ppm. Actual practice indicates that a FC between 3-5 ppm makes the pool virtually trouble free in regards to needed shocking because of CC or in reguard to algae breakouts. This is still lower than the recommened FC level for a manually chlorinated pool with the same 60-80 ppm CYA! No one is able to really explan this but it is suspected that is is caused by the constant 'supershocking' of the pool water as it flows thorough the cell in it's on state.

Running your TA on the low side will increase your pH stability and decrease your acid consumption. Like I said earlier your pool is carbonated. By lowering the carbonation a bit you lower the tendency for CO2 to gas off. Running the TA between ab out 70-90 ppm is a good range for a SWG (or ANY unstabilized chlorine source). The reason the higher TA readings have been so entrenched is because of the widespread use of trichlor and dichlor, both stabilized chlorine sources and both acidic! Having a high TA will cause more outgassing of CO2 and create a tendency for the pH to alway be rising toward aobut 8.2. This nicely offsets the acidic efficts of the trichlor or dichlor and helps maintain a stable pH. This is also why addition of baking soda to increase TA is a regular occuracne with stabilized chlorine and the use of muriatic acid is much less frequent but the opposite is true with unstabilized chlorine (including SWGs) where the use of muriatic acid to lower pH is the norm and very rarely does TA need to be increased (and when it is it is usually increased too much, leading to even worse pH instaiblity and scaling conditions since the pH now alway s wants to rise toward 8.2 until enough of the TA has been destroyed by the additon of acid to get the pH in line!)

Also, running your pH at 7.6 and NOT LOWER will slow the outgassing of CO2. The lower you place the pH the faster outgassing occurs. This is why we purposely drop the pH low when we want to lower TA! My rule of thumb is to keep the pH at 7.6 and when it hits 7.8 it's time to add enough acid to lower it back down to 7.6. A bit of trial and error will soon teach you how often and how much is needed!

Adding borates to your water in a 50 ppm concentration will help with pH stablilty with a SWG, particularly when the TA is run in the 70-90 ppm range jand pH is kept between 7.5-7.9 (a little wider window than without the borates!). There are several reasons why:
It introduces a secondary borate/boric acid buffer into the water which works in the oppsite direction of the carbonic acid/carbonate/bicarbonate buffer we call TA. Instead of moving the pH up it moves the pH down. This effectivly tends to 'lock' the pH around 7.6 to 7.7 for a long period of time compared to without the borates.

It has algaestatic properites so instead of relying on the chlorine to kill nascent algae blooms which are always occuring these are kept at bay. This allows you to run the cell at a lower output since it lessens the chlorine demand (sometimes by quite a lot!) Running the cell at a lower output causes less outgassing of CO2, etc., etc.


Finally, a few things about your ColorQ. Don't trust the CH test if your calcium levels by a titration test are within 100 ppm of the upper limit of the ColorQ (which means if your calcium when titrated is above 300 ppm!) This is a known problem with all of LaMottes colorimetric based CH tests that they do not like to disclose. I use LaMotte water testing at work and only after presenting them with repeated documentation of discrepencies between the results I obtained with their Waterlink Express and with EDTA based titrations for calcium hardness when calcium levels were high did they admit that the calcium test can become very inaccurate and read low when the calcium range is either higher than the meter's range or withing 100 ppm of the upper limit of the range! You should have no problems with the other tests in the kit but be aware that some of the precision ranges are greater than for the same tests done with a Taylor kit (CYA, TA, CH). This, once again is because of LaMottes colorimetric tests vs. a drop based titration test. (I'm talking about the TA test here).
The Chlorine and pH tests are going to be extremely accurate but be aware that the chlorine test is a DPD test so it is susecptible to bleach out when the chlorine levels are aboeve 10 ppm, leading you to believe that there is no chlorine in the water when the chlorine levels are actually high. This is not just a LaMotte problem but is common to all DPD chlorine tests (But NOT FAS-DPD titrationt tests for chlorine, nor OTO (yellow) tests for TC)
Also, be aware that pH should NEVER be tested when FC is above about 8-10 ppm because it will read high. Once again, not a LaMotte problem but just an interference between the phenol red indicator used to test pH in pools and levels of sanitizer.
Hope this is helpful.

P.S. I just want to add that I have a large customer base and have had many people come in with problems with their salt pools ranging from black algae and mustard algae! to just not being able to maintain any chlorine and by insuring that the CYA was within range (In EVERY case it was too low!) and maintaining proper pH (Many of them had pH readings of 8.0 and above) the problems were effectively solved (with what ever other treatments might have been needed such as maintaining high FC to kill algae, etc) and have not reoccurred. That alone has been enough to convice me that running the recommened CYA levels for a SWG is the right thing to do even if I did not understand the chemistry behind it!

 

[Padle]

Why for SWG there isn't a target range for FC as there is for LC? Is it because we assume one can easily maintain a consistent level of FC, as opposed to LC?

 

[PoolStored]

Why for SWG there isn't a target range for FC as there is for LC? Is it because we assume one can easily maintain a consistent level of FC, as opposed to LC?

The easy answer is yes. Particularly if you have an even demand and you run 24/7.

I have variable demand, 24x7 SWCG and 70 CYA. My min is 3 (LAVA) and target is 5. I keep my FC between 7-9. My demand can be as high as 5.5 in the summer. 9-5.5=3.5...I stay above minimum.

 

[Poolnerdgrandma]

So are the only benefits not having to lug bottles of chlorine and daily testing?

(I would consider the saltwater feel a subjective benefit)

The reason I ask, is we live in a new age.

I have Walmart plus, so Walmart can deliver chlorine to my home for free (free delivery not free chlorine and I have a water guru. Assuming the levels it measures are close enough, it would remove daily testing.

Just a thought.

Also, because chlorine is being generated consistently, you don't get the highs and lows you do with LC. You have to overchlorinate a bit wit LC, to ensure that the FC level doesn't go too low before you add more LC. With the SWG, once I have it dialed in, there's very little variability in mr FC level unless something external is going on (high bather load, heavy rain, etc.)