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Ammosorb in Aquaculture
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General
Ammosorb is a material very similar in appearance to filter sand as used in pressure sand filters. Ammosorb is also similar in as much that pressure sand filters are theideal units for containing the product when used in aquaculture.
Mechanical pressure filtration is a useful process in freshwater hatchery applications for maintenance of clean clear water. Salmon hatcheries, arctic char systems and other cold freshwater recirculation systems require a means of ammonium control. Biofiltration is the standard process used in aquaculture, however in cold water systems biofiltration is slow and not very effective. Ammosorb ion exchange filtration actually works better the colder the water, this makes ammosorb the perfect filtration media for ammonium control in theses systems. Coupled with the fact that the media will also mechanically clean the water means that the product is providing a dual function
Ammosorb in Hatchery Recycle systems
Ammosorb should be used in recycle systems for ammonium control in cases where the water temperature does not exceed 10 degrees centigrade, because biofiltration is not effective at these low temperatures.
A simple hatchery recycle system will comprise of the following;
Hatchery troughs or tanks, the water passes through these tanks and enters a sump tank. The sump tank acts as a reservoir and also as a primary sedimentation tank. This tank should be cleaned out at least once every day. An ITT pump of a suitable size should be connected to this tank in order to pump the water through a plastic pressure sand filter. For larger systems our stainless steel pressure filters may be employed. On passage of the water through the filter, the ammonium levels will be reduced to less than 0.4mg/l total ammonium. The discharge from the pressure filters is connected to a UVc systems and possibly an ozonation system. This water then enters a sump tank, or header tank with a minimum of a 10 minute residence time before it is delivered back to the fish.
Amount of ammonium removed by Ammosorb
The amount of ammonium removed by ammosorb is a function of water chemistry, the softer the water, or the lower the ionic content, the better the performance of the ammosorb. As a guide 1 Kg of ammosorb will remove from solution 1 to 5 grams of ammonium.
One kg of fish feed will produce in the order of 30 grams of ammonium, therefore your will require between 6kg to 30 Kg of ammosorb in the filter to take care of the amount of ammonium produce by 1 kg of fish feed. The table below shows the amount of ammonium removed by different sized filters, and the relationship to the amount of fish feed added to the system before regeneration will be required.
Filter size ammosorb media kg water flow cub/hr filter ammonium capacity feed given to fish 24" 150 5 30 to 150 grams 10 to 50 kg 30" 200 9 40 to 200 13 to 65 36" 375 13 75 to 375 25 to 125 42" 550 18 110 to 550 37 to 183 42" horiz 1200 40 240 to 1200 80 to 400 stainless steel 1800 100 360 to 1800 120 to 600
The ammonium levels must be checked in the recycle system. If it is detected that the ammonium levels are beginning to increase then the filter should be regenerated. It is recommended that two filters are operated, several days out of phase. This technique means that only one of the filters will become exhausted at a time, and that water flow can be maintained without a loss in filtration performance. Details on how to regenerate ammosorb are given in the section on regeneration.
