KeithW,
Let us know if you do in fact find that salts settle to the bottom of The Liquidator container. Though salt gradients do exist, usually they are maintained (in the ocean for example) by temperature or evaporation gradients. Typically, the Brownian motion (getting hit by water molecules) is enough to diffuse the salt up higher into solution and the gradient typically isn't that strong. Interestingly, the claim is that though salt and possibly sodium hydroxide stay in the lower layer, the hypochlorite (and sodium for charge balance) migrate into the upper layer, at least enough for chlorination. If that is the case, then why wouldn't chloride also migrate since it's even lighter than hypochlorite? Something about this doesn't make sense.
The higher density of hypochlorite solutions does lead credence to the claim by some pool builders that using bleach (and presumably chlorinating liquid) to vinyl pools damages them. If such solutions are poured quickly and not over a return with the pump running, then the liquid will tend to fall to the bottom of the pool. In some above-ground vinyl pools, there is no floor drain so the circulation at the bottom is very poor so the concentrated hypochlorite solution could settle there (of course, this can happen with Cal-Hypo as well, but is more obvious as white granules on the bottom). It's highly alkaline so there is a limit to the actual disinfecting chlorine (hypochlorous acid) concentration of around 10 ppm or so, but that's pretty high. Of course, we have no proof that even such high concentrations of chlorine will be harmful to vinyl -- acidic conditions are known to be damaging, but one person did an experiment with a piece of vinyl in water with concentrated chlorine solution and did not find any degradation, but that was for a short period of time.
Also, let us know if you find any increased evidence of corrosion if you put The Liquidator inside a pool shed near equipment. Even storing chlorine in bottles is risky unless well sealed since the chlorine fumes can be corrosive over time (same is true for acid).
Note that the instructions (found
here) talk about potential scaling unless the pH and/or TA are kept low if the CH is high. This is probably because the water gets alkaline (rises in pH) due to the chlorine and that can cause scaling if TA and CH are high. This is also true for manual chlorination, but is not as much of a problem since its not a continuous buildup.
The really nice thing about this system, in addition to its convenience, is that it introduces a very low level of chlorine through the system even more continually than an SWG system. It's operating whenever the pump is on so if there is one turnover per day, then the concentration of added chlorine is only whatever the consumption is per day, so if that's 3 ppm FC then it introduces chlorine at that rate above what is already in the pool. So the disinfecting chlorine level hitting the pump and other equipment will be roughly double whatever the chlorine level you target in the bulk pool water. That is far less than what happens when you shock the pool so would seem very safe.
Richard
so my TA went to 200. In an effort to reduce it, lots of aeration and muriatic acid (a gallon or so over time) it's back down to 110ppm and 7.2pH so I geared down the aeration. This is going somehwere 