[kwirky]

first things first: take off that silly air valve on the end of the venturi tubing. It'll just clog every few days and never let you properly tune your skimmer. Air valves are only really beneficial for meshwheel skimmers because they can sometimes pull TOO much air through.

Now you adjust your euroreef with either the twist or extendable riser pipe (depending on how old your's is). If it's a twist type, the closer the word "closed" is to the arrow the higher up your skimmate will reach in the skimmer neck. With the extendable type you just raise the tube to raise the skimmate.

The higher your skimmate the "wetter" it will be. Lots of people will tell you "line it up to here" but it also depends on the water level in the sump too. If your sump's water level is different from their's then their recommendation might not work. Running your sump a little higher (while still allowing for power outage back-siphon) will mean that your skimmer pump doesn't work as hard to fill the skimmer chamber with water, thus allowing it to flow harder and pull more air through.

Remember to keep the skimmer neck nice and clean. I never used to think keeping it clean affected performance but I can tell you, looking after 8 euroreefs, that there is definitely a noticeable performance difference if kept clean.

Also remember to keep up with your evaporation. Top off your tank at least once a day or use an auto top-off if you don't have a dedicated skimmer section of your sump that'll keep the water level stable. An unstable water level changes the pressure against the pump which'll fluctuate your adjustment all the time.

HTH...