Water Balance for SWGs

[JasonLion]

For advice on how to balance your water for a SWG read Water Balance for SWGs over at Pool School.

[jvette]

my neighbor across the street also has a pool. He mentioned to me an article in the local newspaper pertaining to using massive amounts of salt in pools to cut down the use of chlorine. It doesn't sound right to me. He has a regular system. Won't the salt be bad for his system? He's been buying it in 40 lb. bags at Lowe's and swears by it and used it all last year and says his pool is fine. It's a plaster pool. Thanks, jvette.

Salt by itself will not cut down on chlorine usage. SWGs manufacture chlorine from salt that is added to the water so without a SWG there is no effect on chlorine usage. Some people add it to the water to improve the feel since a small amount of salt ( around 2000 ppm or so) will bring the water closer to the body's isolelectric point and the water will be less 'irritating' . Too high a salt level can lead to corrosion of pool parts and plumbing and, in worse case, pump, filter and heater damage or failure so to just dump salt into a pool without testing the level is irresponsible at best!

[JasonLion]

Note that "a small amount of salt ( around 2000 ppm or so)" might mean several hundred pounds of salt, depending on the size of the pool. Salt at 2000 is very low compared to ocean water, but is still a substantial amount of salt when you have to carry the salt bags from the car to the pool.

[achristie]

my neighbor across the street also has a pool. He mentioned to me an article in the local newspaper pertaining to using massive amounts of salt in pools to cut down the use of chlorine.

My saltwater system will not even chlorinate if the salt level is too high (I think above 4000 PPM). I'm sure the manufacturer designed the system that way for a reason. And I'd think it's not because the cell can't chlorinate at that high a level, but probably because they know the damage high salt levels can cause and don't want you to have a case for suing them.

[JasonLion]

I don't reccommend salt levels over 5000, but that isn't why some SWGs shut down at 4000, or whatever level. Higher salt levels make the water more conductive and the SWG needs to turn down the voltage to compensate. Many SWGs have a voltage they can't adjust below so they have to shutdown to avoid overheating at high salt levels.

[Phillbo]

I thought higher salt level helped the system to run cooler... I guess only up to a certain level and then it causes an inverse action.

[JasonLion]

It all has to do with the voltage range the SWG is able to adjust over. Once you hit the end of the range on the high salt end, the unit will either shutdown or overheat. On the low end it will simply shutdown. This is different than when you are in the range it is designed for.

[schrody]

So at what point do you take action for high salt levels? And what action do you take? A friend's pool is testing 3840 ppm right now and is asking my advice.

[MikeInTN]

IIRC, the recommended level given in the sticky for SWG's is 200 ppm over the optimum level listed by the manufacturer for the SWG. There will be a high level cutoff for the particular SWG (or should be), which is the definite point for action. My personal opinion, the least amount of salt the better, so I would probably want to lower my level to the recommended level if I was 100 - 200 ppm above it. If the level in your friend's pool is below the high level cutoff for his SWG, then it's just a matter of personal judgement/comfort level.

Only way to reduce the level is to partially drain and replace w/ fresh water.

[JasonLion]

If the SWG isn't complaining and the salt level is below 5,000, I would just let it be. The salt level will come down over time.

[iggy]

4,000 to 5,000 salt. Wow! Now that is extremly high.
After having a SWG pool for a few years I would like to interject my thoughts.
The salt by itself in a regular pool doesn't do a thing except make the water salty.
If you have a SWG it usually needs 2800-3400 salt level so that it chemically reacts with the cell to produce the gas bubbles that is released into the return line of the pool.
If the level of salt is higher than most manufactureres recommendations it will not work efficiently.

1. Get a good accurate reading of your salt level.
This can be hard as all devices are just a general number and can be off as much as 400 points plus or minus.
I have not added any salt to my pool and each time I get a test locally we get a large deviations.
2800 - 3800 points
I know it is around 3200 which is where I want it and so does the Goldline system.

I add a a few cups of acid about every 7-10 days and my numbers are all great!

FC 5
TC 5
Alk 90
pH 7.6
CA 250
CYA 70-80%
A few oz's of clarifier every few weeks during swimming season and all is great.

I just checked and my water temp is 80 degrees so I may jump in this afternooon.
What is your water temp now?

Iggy in the cool part of Arizona where we swim year round..... Well almost year round. LOL

[JasonLion]

The salt by itself in a regular pool doesn't do a thing except make the water salty.

A very large number of people report that adding salt to a non-SWG pool improves the water feel.

If the level of salt is higher than most manufactureres recommendations it will not work efficiently.

This varies, depending on the brand of SWG. Some of them are not affected at all, good or bad. Some of them become more efficient. Some of them shut down, and some of them burn out. All of this, of course, depending on just how much higher than the recommended levels you are.

[RebelRidin]

I recently switched to SWG and added salt to hit 3200 ppm. I was a bit surprised at how noticeable the salt taste was. It might be useful to come up with a recipe for mixing small batches of salt water on the kitchen counter at common SWG concentrations so folks could try out the taste in advance and avoid buyers regret... Any recipe volunteers?

I will note that I did this and added borates to 50 ppm without consulting my wife or giving her any insight into peoples claims ...

The salt taste was noticed but apparently the skin feels better (softer/smoother) and the water is easy on the eyes and nose...

[chem geek]

3000 ppm sodium chloride salt is 0.4 ounces weight of salt per gallon which is about 2 teaspoons per gallon.

50 ppm Borates is 0.059 ounces weight per gallon or 1/3rd teaspoon per gallon of 20 Mule Team Borax plus 0.038 ounces weight of dry acid (about 1/6th teaspoons) to get to neutral pH. For boric acid it's 0.038 ounces weight per gallon or 1/4th teaspoon per gallon.

[civicturbo]

I recently switched to SWG and added salt to hit 3200 ppm. I was a bit surprised at how noticeable the salt taste was. It might be useful to come up with a recipe for mixing small batches of salt water on the kitchen counter at common SWG concentrations so folks could try out the taste in advance and avoid buyers regret... Any recipe volunteers?

My level is about 4000ppm per NPS's little electric wand and 3700 per my test strips. I licked the water and it taste icky, very salty, I had a few beers My girlsfriend just shook her head I also tasted it at 2500 in the past, still icky. Now being as tasting the water isn't a normal part of my swimming experiance I don't mind what it taste like. Being as the ease of maintaining the FC and the great $$$ savings, I'm NEVER going back to a non SWG system, I swear by it and all I use is a pair of inexpensive Intex generators.
My dream is a nice system that has a FC sensor and self adjust, that would be King!

[Sanger440]

I recently switched to SWG and added salt to hit 3200 ppm. I was a bit surprised at how noticeable the salt taste was. ...

I am new to pools this year and bought a new/used house with a SWG. My salt levels are at about 3000 ppm. I some times think I can taste a little salt when I am swimming, but not sure. My wife and kids swear they taste salt, but I think they are exaggerating a bit after watching me dump in 6 bags of salt into the water earlier this year LOL!

No one that has swam in my pool thinks there is any problem with the taste of the water. I have never had a visitor (mostly friends of my kids) say they taste salt. I do think my skin feels better with the salt water after a swim. And my eyes (nor the kids) have never been bothered at all in my pool. Cannot say that about other pools I have swam in.

I have had a few problems getting my 10 year old SWG to work consistently, but since I replaced the cell and senor a week ago, all is well. And my water looks great using BBB (no borax yet).

Charlie.

[physicsguy]

There is something I don't understand. Free chlorine is free chlorine, whether poured from a bleach jug or generated by SWG. If an SWG pool can be successful at only 3-5PPM Chlorine with 80 CYA reading, why wouldn't I receive the same benefit by adding salt to 3000ppm into a conventional pool? The salt must be doing something to make the Chlorine more effective in the presence of CYA, right? I'd love to be able to run 3-5ppm Chlorine in my 80 CYA pool instead of having to drain it 50% and refill it! So would adding salt to 3000ppm in my conventional (pouring from bleach jug) pool do that for me?

[JasonLion]

It isn't the salt that allows the lower FC level, as can be seen by running a pool with salt but no SWG. The current theory is that being able to run at a lower FC level has something to do with the fairly extreme conditions inside the SWG cell, but no one really knows for sure.

[chem geek]

First of all, an SWG can't remain algae free with 3 ppm FC with 80 ppm CYA unless the pool is poor in algae nutrients. We've had plenty of examples of a 3 ppm FC target that simply doesn't work -- it's too close to the edge with high chlorine demand even if algae isn't yet visible. 4 ppm FC is pretty much the minimum required with 80 ppm CYA and as a minimum that's a number to be measured in the morning after any overnight loss.

Also, remember that the SWG is maintaining the FC level whenever the pump is running so if things are set up correctly where that is mostly during the day when FC loss is greatest, then the FC level is fairly constant. A manually dosed pool will fluctuate in FC up and down so targeting an "average" 4 ppm FC with 80 ppm CYA may have the FC get below that over long enough periods of time that algae can grow. In theory, an automated dosing system, such as a peristaltic pump, maintaining 4 ppm FC with 80 ppm CYA might work, but we don't have enough experience with those to know for sure.

Also, there is some superchlorination in the SWG itself that might help kill off floating algae though obviously would do nothing against any algae on pool surfaces. The superchlorination in the SWG is different than that from manual dosing using hypochlorite chlorine because the chlorine generated in the SWG at the anode is in very acidic conditions, at least until it meets the water that is very basic/alkaline from the cathode.