I have a client whose irrigation supply is fed by a pump in a creek/small, slow moving river. Around here we have a lot of algae in the water. This system is a 3 zone system with a Hunter Pro-C connected to a pump-start relay for the pump which is run down to the water. His brother has the adjoining property with a similar set up but has 6 zones on a Rain Dial, also with a pump start relay. The customer was having to clean a lot of the filters on the bottom of the rotors and we had to replace several, as well. I suggested that we put in an upstream filter. After some deliberation, he and his brother both asked for them to be installed. I placed the 2” model on both Systems with the 100 micron filters in each. I went back out recently to do some unrelated work and decided to check the filters. To my dismay, the filters have a bunch of algae and gook out of the river on them. It’s good that they are doing their job but it looked much worse than I expected it to so soon. I instructed the owners to flush them monthly using the valve on the bottom and the system on and I think they have been doing it, but I’m second guessing this now. I don’t want to have wasted their money. Should I let it ride, switch to a 60 micron filter, try to set them on a quarterly maintenance deal where I clean or replace the filters? Ultimately, it’s doing it’s intended purpose of keeping thy crap out of the heads but I had hoped for this to be less maintenance on their end. PS- I intended on installing a valve on the bottom and using zone 1 from each system to flush it as I had done this on a job recently. I was not able to do this, however, due to one system only having the 3 zones on the module and the other not having a valve anywhere close to where the customer wanted the filter.