Sumps for recirculating systems. Article coming soon...
To reduce time in the fish room doing water changes, many people decide to go with recirculating systems to house their Bettas. A recirculating system consists of cells or containers to house the fish and an over flow of some sort that drains water down into a sump filled with filter media. The water passes through different types of media to filter out solids and to break down the ammonia and nitrite that will be produced by the fish. Water will then pass to an area that will reheat it and it will be pumped back up and into the containers. A recirculating system will keep a constant supply of heated and filtered water moving about your fish. It has the ability to give consistent and much better water quality than using containers and doing manual water changes. But it also has the ability to provide toxic conditions that will quickly kill or weaken fish so one must think through the system carefully. An often over looked component of this system is the sump used to filter the water and that is what we will look at here.
When considering a recirculating system you have to decide how many fish will be per system. I create handmade barracks and house 48 fish per system. Many other people use beanies and can get close to 100 fish on one system. Obviously the system with 100 fish will need to have much more in the way of filtration than the one housing only 48. Using too small a sump will get you a stressed system that will not be able to handle the wastes produced and will cost you more time and possibly the health of your fish. So you need to spend some time planing the sump.
When it comes to sumps, the general rule of thumb for sizing the sump to the containers holding the fish is you want the sump as big as possible. Not really scientific, but the more water the system holds, the more stable the water parameters will be. Most info on the web deals with sumps for salt water tanks. Bettas are a bit different than reef tanks or other tanks that use sumps because we often pack a lot of Bettas into the gallons that flow through the system. For example, each of my big barracks holds about 10 gallons of water and I house 12 fish in that and four barracks per system So that is 48 fish in 40 gallons. If using beanies you may actually have closer to 33 fish in that 10-12 gallons of water and close to 120 fish in the same 40 gallons of water. So you can see the filtration needs to be more than an after thought.
Most people use large glass fish tanks but others use big rubber totes or tubs for sumps. You can use what ever will hold water. Use care if you decide to use rubber totes as many will bow quite a bit when filled with water and may need some reinforcing to use as a sump. If the thought of buying a new large tank only to use as a sump is unappealing, check out Craigs List as you can often find good deals there. Another way to get a good sump tank is ask a local fish shop if they have any tanks that are cracked. For the price of some aquarium sealant you may be able to fix a tank for sump use. I paid $5 for a cracked 20 gallon and is has served as a sump for years on a smaller system. For a barrack system it would be good to think 30 gallons or larger. Since a sump usually is only filled about half way when operating, you are only adding 15 gallons to your system with the sump. So you can see why they say larger is better.
Once you decide on what you are going to use for your sump, you need to determine the media you are going to use to filter your system and how you are going to channel the water through it. Typically most sumps have water flow under and over partitions and through media that will trap smaller and smaller particles. Some also incorporate a wet dry combination where water trickles over media that is out of the water. And still other incorporate fluidized beds. All media used will house bacteria that will convert ammonia produced by your fish into nitrite and finally nitrate. But you also want to think about how that media will remove solids from the water as well. Generally speaking you want to filter larger particles first and have the water go through finer mater to continue to filter solids out of the water stream. If you start with a fine media first, you run the risk of plugging it up and reducing the flow. Common media you will find in sumps are bio balls, bio bale, filter floss, and ceramic rings pot scrubbers. For more on Filtration Media see our article. Partitions are designed to house the various media.
When working out your sump design you will also need to figure in a chamber to house a heater and the pump that will return water to the system. When you purchase a heater remember you are purchasing a heater that will heat the entire system, not just what size your sump happens to be. If you are using a 30 gallon tank but have 60 gallons running through the system you need a heater sized for the 60 gallons, not the 30. You also want to make sure no filter media will come in contact with the heater. And it is a good idea to have your pump so you make sure there is enough room for that as well. My pump pushes 330 gallons per hour and is bigger than my fist, so I allowed 4" of width off the end for it.
To give you an idea of as a place to start, I will explain the design of my sump. Water drains down and onto a plate with holes in it that allows water to drip down into filter floss. This floss should pick up most large particles that come into the sump. At the bottom of this first chamber are stainless steel pot scrubber. There is a lot of surface area in the pot scrubbers and they continue to trap particles in the water stream. The water then flows under a partition and then must go up a good 12" before falling over another partition and onto yet another plate with holes. The space between these two partitions is wide enough to get a siphon hose between them. Very few particles will make it over the top of the second partition and will settle to the bottom of this chamber where they are easily siphoned out.
Once the water hits this second plate with holes it once again drips through and enters a wet dry section. Water initially will trickles over Bio Balls that are above the water line and over others that are below the water line. Water continues to travel down where it passes through and around Pond Matrix. It will then go under another partition and up through some green pot scrubbers. But this time there should be little if any particulate matter in the water stream. From this compartment water enters into a fluidized bed with constantly moving K1 media. The K1 is neat in that as the media tumbles around the old and dead bacteria is constantly knocked off and are replaced with new. It is self cleaning and does an incredible job reducing ammonia.
From this chamber water flows out the back and into a narrow section that houses the heater where it is warmed up. In my sump the water then rounds a corner and is drawn by the pump back up and into the system.
Does one need all this in their own sump? Probably not. What you want to take away from my design is the multi chambers and different media and using things that will house the most bacteria as they are what is going to make your water good again.