can you explain this a little closer?
We are developing a web-based PoolController, dosing liqiud chlorine based on ORP readings. This works pretty well. But we still have "problems" with ORP readings if an SWG is used. It works for about 30-40% of the pools "normal" and for the rest it works ... let's say something between "bad" and "unusable".
"bad" means ... if you try to hold an ORP Level near or over 750mV you need FC levels above or over 2.5 .. 3.5ppm (0 CYA)
"unusable" means, that in some cases the ORP level breaks down to values between -200mV and +200mV and there is no more stable reading possible. The value is kind of bouncing in a range of +/-200mV within minutes.
I've already talked to a chemist about that and in his opinion hydrogen should not be the problem. He said that hydrogen only poorly dissolves in water, and if so, it should be oxidized by the HOCl...?! Well i'm not a chemist ...and maybe you are more experienced in this field. Do you have any further Information about that?
What i don't really understand: it is working in some pools and in some others not. It seems that pools with an "oversized" SWG (i.e. 4000-6000 gallons - 40g/hr SWG) work pretty well. (780-800mV+ at about 0.5 to 0.8ppm FC - 0 CYA). The problems seem to appear only in some pools with "normal" sized cells.
In each case, where the ORP value is bouncing or extremly low a small amout of calcium hypochlorit or sodium hypochlorit, added to the water, is enought to get back a high ORP value. So it looks like something is oxidized then. Do you know what's happening here?