That surface protein/junk can be taken off the top by putting a small piece of thin acrylic on the bottom half of the "weirs" where you overflow into the back chambers. This will increase the amount of water that flows from the surface, rather than pulling water from 2" under the surface. This worked perfect on my 12g cadlights nano. Water pressure will hold the acrylic against the overflow, just cut the acrylic the width of the over flow and about 1.5" tall. You will have to play with how high you place the acrylic, go just high enough on the overflow to get rid of the garbage on top of the water. Oh keep in mind that the little acrylic piece will fall off when you turn off the return pump.