Who rates skimmers

[mr.wilson]

Originally Posted by Mr OM

Dan, if you wanted to remove a film of oil from the surface of a tank of water would you slowly add water to the tank so it comes off the surface slowly and gets caught in a sponge or would you pump it quickly.

The other way to test the theory is to take a small cup and quickly dip it into the tank, then do it again but this time submerge it a millimeter bellow the surface and you will see the surface tension isn't broken as much and water & oil is pulled from a thinner sample, over a greater surface area. You will see it pull water from several feet away.

Having a thin film overflow the surface skimmer will reduce the need for a coast to coast overflow. The best way to test the efficiency of an overflow is to place some flake food at one end of the tank and see if all of it either sinks or gets skimmed within 30 seconds. Any food that gets caught up in the middle, edges or corners means you have dead spots where films will accumulate. These oils are not only bad for water quality, they also diminish lighting intensity, and gas exchange.