One more suggestion,
At the entry point to each tank use a "T" with a check valve between the "T" and the tank(1psi spring). On the downstream connection of the "T" place the valve. Control the valve to open to 95% allowing a small flow to go past the "T" and thus provide constant recirculation...
Hello,
First of all. Is your pretreatment recirculating?
I suggest that during times of non RO operation that you maintain the entire pretreatment system in recirculation. You will have to set up an auto dump feature to introduce fresh water and keep your temperature under the 30degC mark...