Protein skimming, or foam fractionation, is an effective filtration tool when used with closed recirculating systems. Saltwater systems can benefit from protein skimming especially in those carrying high fish loads.

Combining a small amount of ozone with protein skimming improves the performance by oxidizing the available organic contaminants. This leads to better flocculation and absorption of particles onto the bubble wall.

When considering the use of ozone, be certain that the air (preferably pure oxygen) used to feed the ozone generator is dry and clean. The feed gas to the ozone generator ultimately establishes the efficiency and operating life of the equipment. Managing ozone dosing can be achieved with an ORP (Oxygen Reduction Potential) Meter.

HRT = hydraulic residence time

Different filtration equipment is suited to handling different particle sizes.

Suspended solids may be removed using foam fractionation, diatomaceous earth filtration or membrane filtration. Suspended solids are a technical problem in recirculating systems. As these solids accumulate they can cause slowed growth and reduced immune resistance (disease susceptibility). Solids removal (faeces, uneaten feed, bacteria flocks, and other solid particles) is key to successful production. Conventional mechanical bead filter separation and foam fractionation, are suitable to remove large particles and fine solid matter.

2022 models

 
A protein skimmer is the most commonly used equipment by aquarium and aquaculture to remove suspended and dissolved waste from fish tanks by means of air floatation. Protein skimming is a relatively simple process which relies on the physical and chemical properties of coagulation. Protein skimming process requires a contact column in which air and water containing these surfactants can interact. The air and water interfaces are provided by supplying a constant injection of small bubbles to a proportional volume of water in the column and allowing them to mix and then migrate to the surface. During this migration, suspended and dissolved organic material (protein is a specific class of organic material) congregate at the air/water interfaces, with the bubbles forming a “skin” like character on their surface. At the upper levels of the column most of the water drains away leaving a concentrated residue of foam composed primarily of organic material. The skimming off of this foam waste removes it from the life support system. It is, therefore, no longer susceptible to undesirable microbiological degradation which will contribute to increased oxygen demand in an aquatic system. Protein skimming is essentially a perpetual backwash filter. In addition, skimming enhances the oxygenation of a system both biologically and physically. Biological oxygen demand is
reduced by the direct removal of biodegradable organic carbon (protein), as well as bacteria in the water column. Physically, the increased surface area provided by the
injection of large volumes of air (in the form of small bubbles) into a column of water creates a condition for gas exchange. The addition of a small dose of ozone to the process, with its coagulative and disinfectant properties, makes skimming possibly the best component one could add to a modern life support system.

Economical models