Is my pool an appropriate candidate for SWG?

[LGH]

Hello. Since moving into a property that had an inground pool in the backyard 8 years ago, I have been getting advise from TFP but I think this is the first time I am posting a question. When I started taking care of the pool, the stabilizer level was very high. I ended up draining half of the pool and refilling with new water to get it down to 30ppm. I had been using liquid chlorine and then found NST (non stabilized tabs) which I used last year. At the end of the season my skimmer basket was brown which I read was copper precipitating out of the water. I am tired of buying the now expensive liquid chlorine and I don't want to deal with the tabs so I am looking into SWG. My only concern is corrosion.

Here are the details of my pool:

My pool was installed around 1982. I think it is an Imperial Pool. It is a vinyl lined 18.5'x40.5' grecian pool with a 3' shallow end and a 8' deep end. I think its somewhere in the 28-30k gallon range. The liner was last replaced in 2005. There are two return jets, one in the deep end and one in the shallow end. In addition to the skimmer, there used to be a bottom drain but the plumbing for that failed before I owned the pool so that is now defunct. I live in North Western Vermont - the pool opens around memorial day and closes around labor day.

Now the corrosion concern items:

There is an aluminum coping around the edge of the pool. There are no metal ladders, I have plastic stairs. It has a Hayward Perflex DE Filter and a Hayward Variable Speed pump. No heater. My main concern is the skimmer inlet. It appears as though the screws that hold the trim on around the square opening on the pool wall have some rust on them already. There also appears to be a steel (likely stainless steel) backer behind the trim piece. I am assuming that this is what the screws thread into (see images). The screws that hold the return jets in and the bottom drain cover look OK.

The SWG I am looking into is the CircuPool RJ-60 PLUS Salt Chlorine Generator and I was thinking about using a Pool Tools 104-D Zinc Anode to counter act and potential corrosion. I feel like the anode may not be necessary but it is cheap insurance just in case. The return jet line to the deep end is longer then the return jet line to the shallow end so I am assuming there is less of a pressure drop (and therefore, more flow) to the the shallow jet. With that in mind, I was thinking of adding the SWG system to the plumbing for the shallow jet to try and equalize the flow to the two jets rather then through them further off (see images). I also thought it would be better to only install on one of the return lines just incase the SWG clogged for some reason - this way, water would still be moving.

Question 1: does anyone have experience installing a SWG on a pool similar to this and should I be concerned with corrosion?
Question 2: If the trim screws and backer plate around the skimmer opening are a concern, can I replace them? If so, do I have to drain the pool below the level of the skimmer opening to do it?
Question 3: is my proposed layout for the SWG system sound?

 

[Bperry]

Hello. Since moving into a property that had an inground pool in the backyard 8 years ago, I have been getting advise from TFP but I think this is the first time I am posting a question. When I started taking care of the pool, the stabilizer level was very high. I ended up draining half of the pool and refilling with new water to get it down to 30ppm. I had been using liquid chlorine and then found NST (non stabilized tabs) which I used last year. At the end of the season my skimmer basket was brown which I read was copper precipitating out of the water. I am tired of buying the now expensive liquid chlorine and I don't want to deal with the tabs so I am looking into SWG. My only concern is corrosion.

Here are the details of my pool:

My pool was installed around 1982. I think it is an Imperial Pool. It is a vinyl lined 18.5'x40.5' grecian pool with a 3' shallow end and a 8' deep end. I think its somewhere in the 28-30k gallon range. The liner was last replaced in 2005. There are two return jets, one in the deep end and one in the shallow end. In addition to the skimmer, there used to be a bottom drain but the plumbing for that failed before I owned the pool so that is now defunct. I live in North Western Vermont - the pool opens around memorial day and closes around labor day.

Now the corrosion concern items:

There is an aluminum coping around the edge of the pool. There are no metal ladders, I have plastic stairs. It has a Hayward Perflex DE Filter and a Hayward Variable Speed pump. No heater. My main concern is the skimmer inlet. It appears as though the screws that hold the trim on around the square opening on the pool wall have some rust on them already. There also appears to be a steel (likely stainless steel) backer behind the trim piece. I am assuming that this is what the screws thread into (see images). The screws that hold the return jets in and the bottom drain cover look OK.

The SWG I am looking into is the CircuPool RJ-60 PLUS Salt Chlorine Generator and I was thinking about using a Pool Tools 104-D Zinc Anode to counter act and potential corrosion. I feel like the anode may not be necessary but it is cheap insurance just in case. The return jet line to the deep end is longer then the return jet line to the shallow end so I am assuming there is less of a pressure drop (and therefore, more flow) to the the shallow jet. With that in mind, I was thinking of adding the SWG system to the plumbing for the shallow jet to try and equalize the flow to the two jets rather then through them further off (see images). I also thought it would be better to only install on one of the return lines just incase the SWG clogged for some reason - this way, water would still be moving.

Question 1: does anyone have experience installing a SWG on a pool similar to this and should I be concerned with corrosion?
Question 2: If the trim screws and backer plate around the skimmer opening are a concern, can I replace them? If so, do I have to drain the pool below the level of the skimmer opening to do it?
Question 3: is my proposed layout for the SWG system sound?

Any corrosion concerns are the same for a salt pool and non salt pool. Water is what really corrodes stuff. Salt pools are not ocean salt water and many times the salt build up from chlorine and acid over time is about the same as a salt pool.

 

[drsipe]

In all reality, if you have been using liquid chlorine or any other form of chlorine without performing a fresh water exchange for any great length of time, your salt level is probably either at or close to that of a salt pool. When chlorine is consumed. it forms salt, which in a chlorine pool, the salt just builds up. In a salt pool, the salt is broken through electrolysis to sodium and chloride, chloride being chlorine. When the chlorine is consumed, it forms salt and the process starts all over. So you see a chlorine pool is a salt pool and a salt pool is a chlorine pool. There is little difference when it comes to corrosion.

I converted from tablets and powders five years ago, when I found the TFP method, after one year of liquid chlorine and many ruined shirts and shorts, I switched to SWG, and I love it. If my SWG dies tomorrow, I will start using liquid chlorine to hold me off just long enough to get a new SWG. Over the long run the SWG may, or may not save me money, but it's defiantly less work, less mess, and more consistent.

 

[LGH]

Bperry and drsipe,

Thank you for the quick response - I appreciate it. Given that it sounds like converting to SWG shouldn't increase corrosion issues, I am going to make the leap. Any advise on the install? Do you think installing as I described is a good option or would you suggest something else? drsipe - given that you are running with similar equipment, are you running an anode? Is it necessary?

Thanks!

 

[Bperry]

Bperry and drsipe,

Thank you for the quick response - I appreciate it. Given that it sounds like converting to SWG shouldn't increase corrosion issues, I am going to make the leap. Any advise on the install? Do you think installing as I described is a good option or would you suggest something else? drsipe - given that you are running with similar equipment, are you running an anode? Is it necessary?

Thanks!

The anode wont hurt anything but also wont help any.

 

[LGH]

OK - sounds good on the anode.

I did a little more reading last night and the manual for the CircuPool RJ-60 PLUS Salt Chlorine Generator suggests the following water chemistry:

Free Available Chlorine 1.0 - 3.0 ppm
Salinity 3000 – 4000 ppm
pH 7.2-7.8
Total Alkalinity 80 – 120 ppm
Calcium Hardness 200 – 400 ppm
Stabilizer (Cyanuric Acid) 30 – 50 ppm
Saturation Index (LSI) -0.2 – 0.2 (0 Best)
Phosphates & Nitrates None (0 Best)
Metals None
TDS <1200

First, just to be upfront, I have been having the pool store test my water and provide reports - they use ClearCare Expert Water Analysis System.

I am used to balancing Chlorine, pH, Alkalinity, Calcium Hardness, and Stabilizer. I don't think it will be difficult to balance salinity. My total dissolved solids are around 430ppm last I checked and it looks like I can get an app to calculate LSI. My concern is with 'Phosphates & Nitrates' and 'Metals'. Where I am, fill water comes from a lake that has high phosphate loading so my pool has around 1880 ppb (from pool store test) and, like I said, the non stabilized tabs were precipitating a brown substance that was sticking to my skimmer basket which I believe was copper. I am not sure how easy it is to strip the water of these. What is the best way to get good numbers for all of these factors? Pool store testing, personal test kit? I know the Taylor K-2006C test kit is highly recommended but it does not look like it covers all of the parameters above.

Questions:

1. Will running with high phosphate and copper be very detrimental to the SWG?
2. If so, how difficult is it to remove these from the water?

 

[Bperry]

1. Will running with high phosphate and copper be very detrimental to the SWG?

Neither is relevant to running a SWG specifically, but phosphates are largly irrelevant to a pool thats properly chlorinated. I’ve never had a phosphates test.

Copper is another story. Copper can cause ugly staining and so you dont want to ever use copper containing minerals in the pool. They dont actually do what the makers claim and they dont tell you the damage they do. Look up some pictures of what copper staining looks like to see what I mean.

1. If so, how difficult is it to remove these from the water?

Only way is to drain the water and replace it with fresh water.

 

[Bperry]

What is the best way to get good numbers for all of these factors? Pool store testing, personal test kit?

Your own test kit is the best choice. The fancy computers at the pool store have been shown to be both unreliable and inaccurate. Some think its on purpose so they can sell you junk you dont need but I suspect it more likely incompetence, lack of maintainance/training, and lazyness. I dont think they know any better.

The TF-100 (salt) is best deal for how TFP does things. The Taylor K-2006C is also just fine. If you go that way, make sure it has the “C” on it as that has the larger reagent bottles instead of the tiny bottles.

 

[LGH]

Sounds great - Thank you. I just noticed that the Pool Care Basics > Recommended Levels page suggests that SWG pools should use a much higher stabilizer range then a liquid chlorine pool (70-80 ppm rather then 40-50 ppm). This is different then what the manual for the SWG suggests (30-50ppm).

Why is this?

 

[bobloblaw42]

SWG cells have a finite life. Running at a higher stabilizer level reduces FC extinction due to UV. As a result, you can dial in your SWG production to maintain the required higher FC level (which you need at higher CYA levels) and this can be achieved on less run-time than would be needed to maintain the slightly lower FC targets associated with lower CYA levels. In plain terms its like saying, you need to run your SWG less to maintain 10FC at 70CYA than to maintain 7FC at 40CYA (all other things being equal). Less run-time per day = more days before you have to replace your SWG cell.

 

[Bperry]

Sounds great - Thank you. I just noticed that the Pool Care Basics > Recommended Levels page suggests that SWG pools should use a much higher stabilizer range then a liquid chlorine pool (70-80 ppm rather then 40-50 ppm). This is different then what the manual for the SWG suggests (30-50ppm).

Why is this?

Its a recomendation only. Its perfectly fine to keep CYA in the 30-50 range and wont hurt anything. The difference is that some smart people have figured out that running 70-80 (especially in really hot/sunny areas) can protect the chlorine a bit better and hence be more efficient.

 

[LGH]

bobloblaw42 and Bperry-

Thank you for the information - I appreciate it.

 

[drsipe]

I do not have an anode, and do not think that it is necessary, but as stated earlier, I don't think it will hurt.

I use the water chemistry recommendations here on TFP, so depending on the type of pool you have. I have a vinyl pool, but I have fiberglass steps, so technically I could use the vinyl pool recommendations, but I prefer to use the fiberglass pool recommendations to better protect the steps. Unfortunately, my steps have some damage from poor water chemistry before I discovered TFP.

This is the water chemistry recommendations for a vinyl pool.