I found out the hard way that the Seio controller is not my favorite piece of hardware. It reduces the flow of both pumps simultaneously to about 50% and then back up to 100%. The limited options don't make it worth it IMO, and I found that it made my Seio 1100s noticeably nosier, hence I abandoned the controller within 24 hours of buying it and later migrated from the Seios to Koralias.