Just went and checked. I'm using a sicce 1.0 on the IM20 but a 1.5 on the IM25. The stock nozzles put a lot of back pressure on the pump though. I think if you went with a 1.5 and opened up the nozzles a bit you might be able to dispense with the PH. I'm a big flow guy though; also have a MP10 on the wall of the IM25
Using one of those really small Jebao PP2 pumps on the IM20 and they're pretty unobtrusive.
