I have managed to get this to work on my own pool and spa but it depends on daily run time. Having a slight overdraw or underdraw can be a problem if you are running 24/7. However, when I did this, it was only for 6 hours per day run time. Since the valves are in partial open for both suction and return, having a few inches of gain or loss per day in the spa is equalized during the period of time when the pump is off. With the pump off and a connected primed channel between the pool and spa, water will seek it's own level via siphoning and the water level in the spa and pool will equalize to the same level. As I said before, it requires some tweaking so you don't have too much under/over flow in the spa but you can get it to work. It works even better if you have a variable or low speed pump where you can run both on the lower speeds. But again, if you don't want to bother with this then just use the manual swap method.

Scott- Sorry, but I didn't understand your response above.....So do you think the copper filtration system isn't a wise choice? It hasn't been installed yet, we are still in the demo phase of the pool remodel (actually we are now building a smaller pool inside our older 20x40 and straightening it out, it was built on a skew from the house in 1957). I can still change my mind. I spoke with my pool cover guy and he said they have treated the parts in the vault that would be at risk of corrosion to try and mediate this issue, but they still have the disclaimer in their contract if you have a salt chlorinator system.

barco: Wow so now the guys over at troublefreepool idiots, ouch. Well here is a response by Chem Geek talking about this exact issue and why you and I would be wrong and how it is CO2 outgassing, where did he go wrong: "I just wanted to correct what you said technically because what you said was not exactly true and I don't want the main point of running with lower TA helping to reduce the pH rise get lost because of technical inaccuracies. The salt cell has the following two primary reactions: 2Cl- --> Cl2(g) + 2e- 2H+ + 2e- --> H2(g) --------------------- 2H+ + 2Cl- --> Cl2(g) + H2(g) The chlorine gas almost immediately dissolves in the water with the following reaction to have a net reaction as shown: Cl2(g) + H2O --> HOCl + H+ + Cl- -------------------------------- H+ + Cl- + H2O --> HOCl + H2(g) Because water dissociates, the above reaction is normally written with a net reaction as follows: H2O --> H+ + OH- ---------------------------------------------- 2H2O + Cl- --> HOCl + OH- + H2(g) So the bottom line net reaction with the generation of chlorine in a salt cell (ignoring side reactions) is that water and chloride ion (from salt) combine to form hypochlorous acid (HOCl) plus hydroxyl ion (which is basic or alkaline) and hydrogen gas. Since hypochlorous acid is a weak acid, this net reaction is weakly basic (alkaline). This is where most SWG manufacturers (at least their salespeople) believe that the rise in pH comes from, but they are wrong (keep reading to find out why). This is pretty much exactly the same thing that happens when you add chlorinating liquid or bleach to a pool as follows: NaOCl --> Na+ + OCl- OCl- + H+ --> HOCl H2O --> H+ + OH- -------------------- NaOCl --> Na+ + HOCl + OH- except that you get some sodium ion as well (plus some extra salt, NaCl, that is in sodium hypochlorite solutions due to how they are made) and you don't get the hydrogen gas. Now we need to look at what happens to chlorine (regardless of source) when it gets used up. Most chlorine in pools gets broken down by sunlight and even though Cyanuric Acid (CYA) combines with chlorine to form a chemical compound that slows down this process (and is not an effective disinfectant or oxidizer), it still happens as follows: 2HOCl --> O2(g) + 2H+ + 2Cl- The next most common thing that happens to chlorine is that it combines with ammonia or related compounds such as urea from sweat as follows where I show the reaction going all the way to "breakpoint" assuming that shocking occurs (which it usually does if you have sufficient chlorine in your pool and especially when exposed to sunlight which helps the breakpoint process). I'm not going to show what happens when chlorine combines with organics, but the process is somewhat similar (carbon dioxide is produced if the organic is fully oxidized, but more typically intermediate compounds are produced that don't breakdown quickly). 2NH3 + 3HOCl --> N2(g) + 3H+ + 3Cl- + 3H2O So, even though the generation of chlorine resulted in hydroxyl ions, the usage of chlorine results in hydrogen ions and these cancel out forming water: OH- + H+ --> H2O So the bottom line in an SWG pool is the following reactions: 4H2O + 2Cl- --> 2HOCl + 2OH- + 2H2(g) 2HOCl --> O2(g) + 2H+ + 2Cl- --------------------------------- 2H2O --> 2H2(g) + O2(g) 6H2O + 3Cl- --> 3HOCl + 3OH- + 3H2(g) 2NH3 + 3HOCl --> N2(g) + 3H+ + 3Cl- + 3H2O ------------------------------------------ 2NH3 --> 3H2(g) + N2(g) So the bottom, bottom line is that the net result in an SWG pool from the creation and usage of chlorine is that water is split to produce hydrogen gas and oxygen gas or that ammonia (urea) in the water is broken down (oxidized or "burned" in some sense) to produce hydrogen gas and nitrogen gas. These net, net reactions, as you can see, are neutral. At this point, you can now talk about the source of rising pH being the outgassing of carbon dioxide from the pool. You should explain that pools are in essence intentionally over-carbonated, similar to a lovely tasty carbonated beverage! This is done when you initially added baking soda or sodium bicarbonate to your pool (it also happens when you add some pH Up products that have sodium carbonate). The purpose of having extra carbonate in your pool is to act as a pH buffer and to provide carbonate ion that, along with the calcium you added to your pool with calcium chloride, saturate the water with calcium carbonate so that this compound does not get dissolved out of plaster/gunite/concrete/grout. If too saturated, scaling would occur essentially precipitating calcium carbonate on to pool surfaces. Also, the calcium carbonate tends to form a thin film layer on metal surfaces that help reduce corrosion, though pH is a much more important factor for metal corrosion. Pool water chemical balance attempts to keep a balance between corrosion and scaling. The downside of having a pool over-carbonated is that there is more carbon dioxide in the pool than in the air so there is a tendency for it to outgas. When this occurs, the pH rises while for technical reasons I won't get into here, the Total Alkalinity (TA) remains the same. If you then add acid to restore the pH, you lower both the pH and the TA with the net result of having TA get lowered -- which makes sense since TA is partly a measure of the amount of bicarbonate in your pool. The carbon dioxide outgassing, and therefore the rise in pH, is increased when the TA is higher, when the starting pH is lower, and when there is more aeration. So the easiest ways of reducing this rise in pH are to lower the TA, keep the pH higher, and reduce aeration (waterfalls, spillovers, etc.) including using a pool cover. For an SWG pool there is another way, in addition to lowering TA, that can help reduce the pH rise. That is to add an additional buffering system to the pool that is also an algicide that will cut down chlorine consumption. Adding 50 ppm Borates (from Borax, the 50 ppm technically being Boron) to your pool will add additional pH buffering capability so that you can keep the carbonate part of the buffer lower. To compensate for water balance, you need to keep either your calcium level or your pH higher (or both). The algicidal properties of the borates lower the consumption of chlorine which will let you lower the output of your SWG which lowers hydrogen gas production so less aeration so less carbon dioxide outgassing and less pH rise. Whew!"

Well I didn't have any luck finding the web pages I found back then about the interaction of ozone and sodium bromide as the primary form of sanitization. Here's a copy/paste of what I did find """Protocol for total pool management is as follows. 1. Use of ozone as the primary disinfectant. 2. Use of sodium bromide as the secondary stable disinfectant. This is the natural constituent to sea water which can not act on its own. Needs the ozone to activate it. 3. Use of hydrogen peroxide for super oxidizing the pool. 4. Use of an algaecide if necessary. In an ozone treated pool, ozone activates sodium bromide to hypobromous acid. Ozone (O3) +Sodium Bromide equals Hypobromous Acid. Hypobromous acid is one powerful bactericide and is more powerful species than chlorine and more stable than Ozone. Hypobromous Acid +Organics equals Sodium bromide. Cycle is set up with the ozonation system in which the sodium bromide goes from the bromide to the hypobromous acid and then back to the bromide. In this way the bromide losses are minimized and one only has to add sodium bromide once each 6 month period to compensate for losses from backwashing""" What I liked about this set up was that it was a very hands off system which really delivered a very strong disinfectant, Because I have a very very large pool what I didn't like about the system was that there was no residual and I would have to circulate 24/7/365. I run 3 equipment sets and thought about dedicating one for the ozonator to handle it and let the other 2 run on normal daily cycles. I also didn't like the price of the commercial grade ozonator. I really didn't want a salt system because I have an Arizona flagstone which doesn't like salt systems and I didn't like the price of the 3 SWG's it would of taken to handle my pool size. So, I ended up with no system at all. Kind of stupid on my part, LOL!!! I use the BBB method, it's a daily regimen of adding bleach every morning and checking the balance of my chem's once weekly. I keep crystal clear water but can't miss a day of chlorinating because I run a low stabilizer PPM and my pool will grow algae almost instantly if I miss doing it. See ya, Kelly