Seeking recommendations for inline vs offline clorinators for an AGP

Kevin R.

Member
Sep 11, 2019
11
Central Texas
Greetings All,
I have been searching for advice/recommendations on chlorinators for my AGP.
I currently have a 12'x24'x52" Intex with a Sand Filter pump.
Due to the location of my pool, I need to have a cover during fall and winter months that make it hard for me to add chlorine pucks(I've noticed these are frowned upon here)
I would like to add either an inline or offline chlorinator, but am unsure on which is best for my situation.
I have a deck all the way around my pool, so crawling underneath is my only option.
Can somebody recommend a product that will allow me minimum maintenance while still keeping the water at a level that I won't open up the pool in the spring and have a green lab experiment to deal with.

Thank you all in advance!
Kevin R.
 

Rattus Suffocatus

Silver Supporter
Jun 5, 2019
430
Corona de Tucson, AZ
I researched this in the beginning when I considered it when building the pool. the Pentair Rainbow series seems to be the best. The Hayward version has a bad reputation (and I have Hayward equipment). If you DIY all of them are pretty cheap online and not difficult to install.

As for using Trichor or other stabilized chlorine (dichlor)... it adds a lot of cyanuric acid (CYA) to the pool at the same time. If you have cheap water, then you can just drain once you hit 90 ppm CYA or so if you insist on using them only. You can delay this by using some bleach as well.

If you use chlorine gas (either from a pool service or a saltwater chlorine generator) or liquid chlorine (bleach, Sodium Hypochlorite, which adds salt) then the CYA doesn't go up from adding the chlorine. The only other options are Calcium Hypochlorite which eventually will get the calcium levels too high or the very expensive and increasingly less available Lithium Hypochlorite which adds a lithium salt that is harmless.

Having said that, if I were still in the Midwest where the water was all over and very inexpensive I would probably use Trichlor and do a partial drain and refill on a schedule. In AZ, that's a bit pricey (though not as horrible as I thought) and it definitely is wasteful of a scarce local resource.

Hopefully that clears up the issue of why Trichlor is frowned upon here in most cases. Right now I'm trying to get my CYA up a bit so I'm using pucks myself in a floater. Probably for another week or so (stop at 30 or 40 for winter). And again next year to get it up to a level acceptable for the summer Tucson sun (50 to maybe 60).

This is why too much of a good thing is often really bad. If you exceed this you will have algae and potential sanitation issues. FC/CYA Chart
 
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Kevin R.

Member
Sep 11, 2019
11
Central Texas
Thank you for that information.
I have had reservations about using anything with salt due to concerns about it rusting the metal frame work around the pool.
Have you heard of anyone on here having any issues with their frame work rusting using salt equipment?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
10,465
Northern NJ
Thank you for that information.
I have had reservations about using anything with salt due to concerns about it rusting the metal frame work around the pool.
Have you heard of anyone on here having any issues with their frame work rusting using salt equipment?
You are adding salt to the water every time you add shock/liquid chlorine/bleach.

For every 10,000 gallons adding a gallon of 10% liquid chlorine will raise FC by 10 ppm and salt by 16 ppm.

Chlorine is a gas and needs to be bound to other chemicals - CYA with trichlor and dichlor; calcium with cal-hypo; water and salt with liquid chlorine.

You can decide which byproduct chemical you want to manage in your pool water.
 

Donldson

TFP Expert
LifeTime Supporter
In The Industry
Jun 12, 2009
3,943
NW Ohio
The corrosive properties of water at salinity found in an SWG pool are horribly overblown. In reality the more concerning thing that can cause damage to metal in and around a pool is acidic water. This can happen when a constant source of acid is added to the water without properly adjusting for it. What is the most common source of acid added to pool water? Chlorine tablets.
 

Rattus Suffocatus

Silver Supporter
Jun 5, 2019
430
Corona de Tucson, AZ
So, just as a reference, sea water has a salinity level of 35,000 PPM on average (3.5%). A typical SWCG runs in the 2500-3000 PPM range (0.25 - 0.3%). So less than 10 times less. The USGS classifies this as "slightly saline water".

So for every liter of salt pool water there is at most 3 grams of salt...

So, does it contribute to corrosion? Yes. But at least 10 times less than sea water.
 
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wireform

Silver Supporter
In The Industry
Aug 15, 2017
464
Spring Valley, NY
So, just as a reference, sea water has a salinity level of 35,000 PPM on average (3.5%). A typical SWCG runs in the 2500-3000 PPM range (0.25 - 0.3%). So less than 10 times less. The USGS classifies this as "slightly saline water".

So for every liter of salt pool water there is at most 3 grams of salt...

So, does it contribute to corrosion? Yes. But at least 10 times less than sea water.
I will say a properly balanced SWGC pool will have almost the same corrosion as a chlorine pool. There are members here on the forum that have perfectly balanced salt water pools for years and don't have any more corrosion then the chlorine pools here.
 

Kevin R.

Member
Sep 11, 2019
11
Central Texas
Well I am happily amazed at this information.
I guess that old adage about how one should not "assume" fits this case well.
Again, a big Thank You to all who have instructed me on something I was not aware of.
I may need to rethink my entire system here.
But just to get me through the winter, the Pentair Rainbow 320 looks cheap enough.
I just hope my dinky Intex Krystal Clear 12" sand filter pump will have the pressure needed to make the Pentair Rainbow 320 work efficiently.
Again, Thank You Guys!
 
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Kevin R.

Member
Sep 11, 2019
11
Central Texas
I researched this in the beginning when I considered it when building the pool. the Pentair Rainbow series seems to be the best. The Hayward version has a bad reputation (and I have Hayward equipment). If you DIY all of them are pretty cheap online and not difficult to install.

As for using Trichor or other stabilized chlorine (dichlor)... it adds a lot of cyanuric acid (CYA) to the pool at the same time. If you have cheap water, then you can just drain once you hit 90 ppm CYA or so if you insist on using them only. You can delay this by using some bleach as well.

If you use chlorine gas (either from a pool service or a saltwater chlorine generator) or liquid chlorine (bleach, Sodium Hypochlorite, which adds salt) then the CYA doesn't go up from adding the chlorine. The only other options are Calcium Hypochlorite which eventually will get the calcium levels too high or the very expensive and increasingly less available Lithium Hypochlorite which adds a lithium salt that is harmless.

Having said that, if I were still in the Midwest where the water was all over and very inexpensive I would probably use Trichlor and do a partial drain and refill on a schedule. In AZ, that's a bit pricey (though not as horrible as I thought) and it definitely is wasteful of a scarce local resource.

Hopefully that clears up the issue of why Trichlor is frowned upon here in most cases. Right now I'm trying to get my CYA up a bit so I'm using pucks myself in a floater. Probably for another week or so (stop at 30 or 40 for winter). And again next year to get it up to a level acceptable for the summer Tucson sun (50 to maybe 60).

This is why too much of a good thing is often really bad. If you exceed this you will have algae and potential sanitation issues. FC/CYA Chart
Hello Rattus,
I took your advice and bought the Pentair Rainbow 320.
I noticed in the paperwork that they recommend a "corrosion resistant check valve" which of course did not come with it.
Can I use one from somewhere like Lowe's or Ace, or does this need to be some super duty type check valve?
I had read somewhere that if I have over 12" rise on the pump side, that I don't really need that valve.
If you have any experience with this and don't mind sharing your thoughts, I would be greatful to hear what you have to say.
Thanks again
 
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Rattus Suffocatus

Silver Supporter
Jun 5, 2019
430
Corona de Tucson, AZ
The Trichlor tabs are rather acidic, so that check valve is for backflow prevention into the pump and/or heater cores. I would probably add it. Plastic check valves rated for the pressure in your system would work fine in this application. I really don't know about the availability of these at Lowe's or Home Depot off hand. I do know that they sell sump pump backflow check valves but I am not certain they are usable under pressure or can be plumbed into a solid PVC line. You will need to look.

As far as 12" head being enough? Probably but I have seen siphons that jumped more than that. Likely you will be ok, but if you can find a proper check valve easily available either locally or on line, I would recommend doing that.

Maybe someone else can chime in on this. I probably will have the same issue when I decide to get a SWCG later next year...