March 18, 2019 at 9:51 pm #8521Ron SieberKeymaster
What’s the best filtration method for your system?
When setting up your aquaponics system you are going to have to consider the best filtration method that works for you. To determine which method to utilize, you will need to consider the size of your rearing tank/pond, the type of substrate you plan to use, and what, if any, grow media you are using for your plants.
The size of your rearing tank/pond, or the total quantity of water utilized, will be a large part of designing your grow beds for your system as well as determining the necessary filtration for your system. The ratio of rearing tank/pond to grow bed should be 1:1. In terms of cubic feet, this would mean that for every 7 gallons of water in your rearing tank/pond you should have at least 1 cubic foot of grow bed. Maintaining this ratio will make it easier to balance the nutrient levels in your system. Once you have determined the size of your grow bed, you will need to calculate the appropriate pump size to use for your system. This can be done simply by following the rule that the total quantity of water in your system should be passing through your grow beds/filters at least every two hours. This would mean that for a 30-gallon tank coupled with a flood and drain bed operating on a 15-minute pump cycle, you would need at least a 60 GPH pump.
Part of your considerations for your filtration methods should pertain to the substrate in your rearing tank/pond. If you are raising tropical fish in an aquarium-based system, you will most likely have a decorative substrate. In these systems, it would be best to add an under-gravel filter to feed into your grow beds. This would allow you to move the most fish waste (ergo nutrients) out of your rearing tank and into your grow bed. This would also in turn minimize the amount of cleaning your tank would require. If you have a larger system for rearing fish for consumption however, you probably do not want to use a substrate at all. This would make the removal of excess waste easier and could be performed with a simple water pump or airlift pump.
The type of media you are using for your plants will also factor into your filtration methods. In the instances where a media such as hydroton or gravel is used, additional filtration is often not needed as the grow media itself acts as a filter. If additional filtration is desired, this could easily be paired to work with an under-gravel filter or a canister unit. If do not want to have a media-based grow bed, Deep Water Cultures or flow beds can be utilized, but must have additional filtration, such as a sump or canister unit. You will also have to pass the tank water through a biofilter prior to passing into the grow bed so that nitrifying bacteria can do their job.
Have you experimented with gravity-fed filtration unit, such as the no clean tanks on a larger scale in addition to other methods of filtration?
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