If you are getting too much pressure from a coolant pump, don’t restrict it. Instead, I put a recirculating line near the pump outlet to divert some of the flow back to the reservoir.
To service several machines that are in close proximity to each other, I use a plastic food stuff barrel (about 35 gallons) to dispense coolant.
Tramp oils cause coolant to go rancid. To prevent this, you can use a skimmer, or what also works is an aquarium bubbler. While the bubbler may not work as well as a skimmer, its bubbles produced keep the oil from covering the surface of the coolant and cutting off oxygen. Lack of oxygen is what triggers bacteria growth.
On-line name BobWarfield Northern Calif.