Kidney loop filtration systems can be thought of as sideline hydraulic filtration systems. They can be turned on or off to filter the hydraulic fluid at will. Because a kidney loop system is not directly exposed to the hydraulic system itself at all times, it is quite efficient in removing dirt from the fluid — as well as holding it in the filter elements without releasing it back into the fluid
So does every system need one? Well, that would be nice. In fact, that would be ideal — that way, if the system is only running for 12 or 13 hours a day and it has downtime in the evening, you can turn the kidney loop on and let it filter a lot of that oil in the reservoir, and clean it out.
That way, the next day you know you’re starting with oil that is as fresh as possible —oil that doesn’t have all the contamination sitting in it. This situation would be ideal, but if you can’t, even a filter cart would be good to set in the tank on one end, and let it run through and pull the oil from one end and kind of refill it on the other end, and move it through the reservoir. Maybe it will stir up some of the stuff on the bottom of the reservoir also, and your filter cart can kind of grab that and remove it.