As I mentioned in another thread I have decided to install a metering pump to feed 5.25% bleach, the pool is at my elderly mother's house, and I typically only get out there on the weekends, so I am hopeful a constant rate of chlorine injection will make managing the pool easier. I have purchased an LMI metering pump (I know it is not perfect, but was an ebay deal new in the box old stock for under $100) The pump is a P121-151S , .2 GPH max at 150 psi, polypropylene head with ceramic balls, it also has the optional 4FV valve, not perfect, but maybe I can make do, LMI gives polypropylene a fair rating for use with 5.25% bleach, and I can upgrade to a Bleed 4FV or Autoprime valve if need be for gassing issues.
My plan is to install the pump so it feeds from a bulk container (probably a 5 gallon pail until I find something better) and inject into a T fitting installed on the return line just past the filter. I am not sure if I should install before or after the diverter valve for the roof mounted solar panels, any thoughts, it seems to me there are arguments both ways.
This pump has both adjustable stroke length and and speed, is there one or the other that I should try to maximize/minimize to lower the chance of out gassing?