Protein skimming or foam fractionation is the process by which dissolved and particulate organic carbons are removed from a liquid, in this case the fish culture water, by adsorbing them onto the surface of fine bubbles rising in a closed contact column against a counter-current water flow.
The bubbles burst and form stable foam at the top of the water column and the accumulated organic wastes are discharged from the column along with the foam produced.
The removed substances are called "surfactants" because they are surface active or "charged"
Benefits of Protein Skimming include:-
Removal of suspended solids.
Removal of proteins and high molecular weight compounds.
Increased water clarity through removal of humic and phenolic compounds.
Increased oxygenation of the culture water.
pH stabilisation through removal of organic acids.
Performance is defendant on:
Air to water ratio
Air bubble diameter
Air/water contact time
Use of ozone
Bubble size is the most important of these and within the control of the design of the protein skimmer.
Clean - Clear - Healthy Water:
Ponds are ecological systems in which many factors form a well-adjusted equilibrium. If the pond has too much nutrition (e.g. through leaves etc), the balance is upset. The consequence: the water becomes cloud, it changes colour and becomes contaminated.
Helps clear algae:
When the weather is warm and there is sufficient nutrition, floating and threaded algae increase rapidly. All this leads to the pond as am ecological system becoming unbalanced. The water becomes cloudy, and the other plants do not get sufficient light and die off.
Biologically pure water without chemicals:
Fighting against excessive nutrients by using chemicals can be dangerous. Depending on the composition of the agent, the biological system can be seriously damaged and toxic materials can be generated unintentionally.
Less cleaning required:
Conventional pond filters need regular care: depending on the load they have to be cleaned more or less regularly, and this takes time and is dirty work.