I have the same model, and couldnt be any happier with it. I dont think its the product that is the problem,it's usually user error that is causing the problem. If you bought it recently, you should have gotten the new model, which includeds the new directions, and a new red knob (see pic below).
New instruction manual...
New red knob...see the 5 circles on the top? The older model did not have these, and it would leak.
Did you do steps 4 and 5 correctly? If so, and it still overflowed, then you need start with the red knob in closed position, then slowly turn the knob until bubbles are a little bit above the red retaining ring.
And your Debris Strainer should be about 3" down from the top of the water line.
(If its too high you will get too much air, if its too low you will get too much water.)
I spent hours tinkering with mine when it got it. I also overflowed mine a little the first time I let it rip. My install was even more of a pain because my tank was already setup and I did not have enough clearance between the wall and the back of the tank, so I had to mount mine on the side. It works great, you just have to mess with it.