Does it look like particles in the water causing the cloudiness or is it tiny water bubbles rising to the surface which means you have great flow!?
I have used both the Fluval and the Eheim. The Eheim primes and starts easier as the output comes out the bottom so you can create the syphon effect to remove any trapped air by laying the output hose down and then locking it shut till you connect it to the pipes hanging on the tank. ( I fill mine in the bathtub so there is room to lay the hose down. Then I finish filling the canister and put the top on. Forcing the water up the input tube in this process and then lock that tube shut also.) My Fluval had the in and out on the top... have they changed that set up?? ... which meant priming, or starting the flow was hard and meant sucking on the end of the tube to start it. yuck. If they are both on the top, then after putting on the lid and locking it shut, trickle water down both tubes to fill them. Air in the canister or tubes will prevent the syphon/priming process. You are basically setting up a rotation using a motor to syphon water out, thru and back in. Makes sense?
Both canisters clean the water fabs!! JMO. The shut off valves in the in/out tubes allow you to leave those in place on the tank and take only the filter to the sink/tub. Worth every penny!!! Hope this helps those struggling with cannister priming.