The PROs and CONs of SWG

[needsajet]

After reading a few threads about buying chlorinating liquid I thought of another pro for SWC: no shopping around and checking prices and dates on chlorinating liquid.

 

[kywildcats]

Had my pool put in last September and got to use it for a week before the temperature starting dropping. So this is actually my first year as a pool owner. I have learned SO MUCH from this site, and have not bought anything from the pool store. That being said, I love my SWG!! It makes everything so easy. I would hate to be lugging jugs of bleach week after week. I guess the hardest thing for me is, dialing in my SWG to keep it right where I want it. I think it will be easier when the temps stabilize, and not having to adjust every couple days. I do keep record of the adjustments I make, and I only make them in 5% increase/decreases. Good luck in what ever you decide!

 

[JoyfulNoise]

Wrong.

Cl2 production is directly proportional to the total number of electrons (i.e. electrical current) that moves through the circuit. A "bigger" SWG simply has more electrode surface area (e.g. more plates) than a smaller one does. Consequently, the larger SWG can generate more chlorine gas per unit time, simply because the larger surface area anodes enable more chloride ions to get oxidized (i.e. they can "consume" more electrons per unit time).

Larger SWG units can produce the required chlorine amounts in shorter time than smaller units, but the amount of electrons required is the same in either case.

Stoichiometrically, SWG electrolysis generates one H2 molecule for every molecule of Cl2 that is produced. So the amount of H2 produced (i.e. the driving force of pH rise) only depends on how much chlorine is generated...not how big the SWG is.

Does it? I would think that the same amount of FC added to the pool (big vs small cell), would generate the same amount of hydrogen bubbles given the required reaction balance. A larger cell has more area to generate not only more chlorine but also more hydrogen per minute. It should be directly proportional to production rate which in turn is directly proportional to the cell area. So I don't think it should make a difference.

Thank you, I didn't think I had lost my mind.

Well you guys have certainly been busy...sorry, I was away most of the day and driving so I could not respond. Here's my thinking -

Let me first say that I do not disagree with any of you on the chemistry. For every mole of chlorine gas produced, a mole of hydrogen gas will be produced. So I'm not arguing that there is more or less hydrogen produced, it's the same for the same amount of chlorine (maybe my original post was not clear on that point). Aeration is a physical process, the chemistry of it comes later. As a physical process, the amount of aeration that occurs depends on the geometry of the setup, the flow rates of water and the amount of contact time that the source of aeration has with the water.

An IC-40 produces 1.4lbs of chlorine per day or 0.91667 oz/hour

An IC-60 produces 2.0lbs of chlorine per day or 1.33333 oz/hour

Let say you need to raise the FC by 4ppm in a 15,000 gallon swimming pool - that will take 8oz of chlorine gas. The IC40 requires 8.7 hours of run time at 100% output while the IC60 require 6 hours of run time at 100%. Assuming both plumbing systems are the same and your pool operates at a flow rate of 60GPM (not an unreasonable flow rate but it doesn't really matter as you could use 20GPM if you like), then the IC40 cell will have 60GPM x 8.7 hrs x 60 mins/hr = 31,320 gallons of water flow through it while the cell is producing gas bubbles. By contrast, an IC60 will have 60GPM x 6 hrs x 60 mins/hr = 21,600 gallons of water flow through it.

Unfortunately, aeration processes are not easily quantified but I doubt you can make the argument that there is a one-to-one correlation between the number of hydrogen gas molecules created and the number of CO2 molecules outgassed. Because of this, I'm inclined to conjecture that if you are flowing 31% more water through the IC40 cell while it is running, then you are agitating and expelling more CO2 gas from the pool water that uses a smaller cell than one that uses a larger cell.

 

[mas985]

If that were true, then one should expect the same effect when operating at different pump speeds.

Also, is the primary aeration in the plumbing or in the pool? I would think that since the bubbles are traveling with the water in the plumbing, there will be some out gassing but it will be limited. I would think most of the out gassing occurs once the bubbles reach the pool and rise through the water.

But honestly, I think this is all moot because if the water has a potential to out-gas, it will. The mechanism just determines the speed at which it happens. There are so many other things that happen in a pool that would initiate the out-gassing that one way or another, I really don't think it would make any difference at all.

 

[JoyfulNoise]

I certainly have no way of testing it because I have far greater sources of aeration in my pool. I run a waterfall (very splashy) for ~60mins/day and my spa spillway runs for another 60mins/day. Those two by themselves probably dominate the outgassing rate of the water when no one is swimming.

 

[Schnozz]

Richard. Never thought about the salt affecting the plant life. We live in the same area and I backwash to a row of citrus trees or simply on the grass. Thanks all for responding to the OP. A's we continue to keep up with the forim, we continue to learn. Active members leave posts we may never have considered....thanks all

 

[Chuckiechan]

In addition to my SWG, I borated. Now, I hardly use acid anymore either. Probably 6 gallons a season after start up.

When we go on vacation - I have cheapo pool tester my in laws can use to check FC and PH. (I won't let them touch my Taylor kit!)

It's about as trouble free as you can get as long as you keep the pH in spec.

 

[mgmoore7]

On the plus side, We had 2 families over this past weekend for a pool party, both asked if the pool was swg. Neither knew that a swg is still a chlorine pool but they both said that their kids have issues in traditional chlorinated pools but not swg pools.

Whether this is fact or not can be debated, but Perception is reality to some and the swg made these parents more comfortable that they would not have issues later.

 

[Thimble]

The grandkids came over with friends the other day. The 10 year old friend jumps in, comes up and says "WOW ! My eyes don't burn in your pool."

I'll keep a SWG system as long as I have a pool. Get your water chemistry in a sweet spot and acid addition is a occasional thing to do. Mine has been open since early May and I have added acid twice. pH stays at 7.4 unless we get a huge rain. The wife has plants around the pool and splash out doesn't bother them or the lawn at all.

They are well worth the initial cost.