Keeps tank spotless
I got this to remove the oil film that floats on the surface of the tank. Super easy installation but one thing to note is you do have to adjust the knob on the bottom. The adjustment is what tunes the amount of water being sucked in the surface. Naturally if you close off the bottom slits you will start to suck in air. If you have a working cortex you will have no issue using this glass skimmer. I love it!