oily surface - aquariumalgae_blogspot_com - dusko bojic Ever notice oil slicks in your tank ? If you did, you were probably wondering where it came from. Although it's not harm for your organisms, oil slicks on the water's surface reduce the beauty of your tank. How to get rid of it ?

oily surface - aquariumalgae_blogspot_com - dusko bojic

Oil slicks appearance on the water's surface is especially common in planted aquariums, where surface agitation is purposely minimized to help keep CO2 levels up.

Some possible causes :

Fish food – Most of fish foods contain some fat in their ingredients.
Fish waste contains some fat.
Dead fish - the decomposition of the dead fish releases fat into the water.
Your hands' contamination - Our skin also produces oil, it will contaminate your tank when you dip your hand.
Air pollution - Cooking activities release oils into the air and can be easily carried to your tank, especially if your tank's location is nearby the kitchen.
Equipment - Manufacturers often put some oils at the propeller-shafts in submersible filters or water pumps for lubrication.

Vigorous surface agitation can stir up the surface, creating mixed water to prevent the slick formation.

Is It Dangerous?
The oil slicks may not be dangerous, but it reduces the beauty of healthy aquarium. It also slows down the gas exchange process.

How To Get Rid Of It
First, you should identify the cause or source of the oil, then deal with it, also take some preventions. Oil slicks float on water's surface, it can't be completely removed by slurping the surface. One way of removing the oil slicks is by laying a paper towel gently into the still surface to absorb the oil, then remove it. You should repeat the process several times until all the oils are removed from the surface.

Preventions

Increase surface agitation by adding an aeration, water flow across the surface or using wavemaker. In planted tank where that is NOT acceptable, an aquarium skimmer or surface cleaner can be added. You can read our article that discuss the usage of the aquarium protein skimmers in planted tank.
Perform regular partial water changes to reduce excess nutrients.
Wash your hand with soap to remove oils before you dip your hand into the water.
Thorough cleaning your submersible filters and pumps' parts before you use it for the first time, remove any oil by washing it with soap.
Check your aquarium location, don't put it near the kitchen.

I hope this article can help you to overcome oil slicks' problem. You can read another issues about water quality in our next articles. Enjoy the reading .