If you’re a frequent visitor here at Aquarium Tip Tank you probably know that I am in the process of setting up a 30 gallon saltwater aquarium. Actually, you’ve probably already seen pictures of the Koralia Evolution water circulation pump set up in this fish tank. However, I’m not quite sure that I’ve actually showed you the pump itself and explained who it is made by, why it is necessary, and how it works. I figured it is about time to share that information with you!
First, lets talk a little bit about water circulation in an aquarium. Good water circulation is important in a home aquarium for three main reasons. Water circulation provides a means of food delivery, waste removal, and the provision of oxygen.
In order to adequately disperse and deliver the food that is fed in a broadcast manner to the livestock of your aquarium, water must be circulated around the entire fish tank and to all corners of the aquarium. This is especially important when dealing with sessile invertebrates. After all, they don’t really move. Of course, you can dose individual corals with food filled syringes, but corals and their symbiotic zooxanthellae algae also grab the tiny particles of plankton and nutrients that are floating in the water. In order to make sure that the food an nutrient rich water passes close enough to the sessile invertebrates to feed, good water circulation is necessary.
Not only does circulating water deliver food and nutrients to all parts of a fish tank, but it also picks up and removes waste particles that have been left behind. The oceans have waves, currents, and tides that are constantly creating water circulation that removes waste. In an aquarium, water circulation must be created in order to pick those waste particles up and off of the corals, rocks, sand, and decorations. Proper water circulation will then help bring those waste particles to the inlet of the filtration system so that they can be removed from the aquarium water.
Finally, water circulation in a home aquarium helps with oxygenation of the water. Water does not have the ability to hold as much oxygen as air does. The warmer the water gets, the less oxygen it can hold and warm saltwater holds the least amount of oxygen. If water in a fish tank were left stagnant, only the water in the top water column of the tank would be in contact with the air for oxygenation. Good water movement will constantly circulate all of the water to the air/water interface, allowing gas exchange and proper oxygenation for all of the water in the tank.
Okay. Now that we know why proper water circulation is important in a home aquarium its about time I show you some pictures of how I’m moving the water around my 30 gallon reef tank.
Most manufacturers show flow rates and recommended tank sizes for their pumps. As shown below, Hydor provides a chart on the back of their Koralia Evolution Movement and Circulation pumps.
A very general rule of thumb that is used when it comes to flow rates is that water circulation should be at a flow rate equal to ten times the net water volume of the tank for soft corals. For example, I’m putting this pump in a 30 gallon tank. Therefore, the flow rate for water circulation should be at least 300 gallons per hour (gph) if keeping soft corals. For hard corals, a flow rate equal to 30 times the net water volume of the tank can be used. Therefore, for hard corals, the general rule of thumb states that I would need 900 gph of water circulation.
I’m currently only putting one Koralia Evolution 550 gph Movement and Circulation pump into the tank, and that should work for right now. When I decide to put hard corals into the tank I may need to add another pump for a total of 1100 gph from power heads. However, some water circulation is also produced by filter returns and protein skimmers and another power head may not be necessary. That is a decision for future TJ to make.
Shown above is the Koralia Evolution 550gph pump by Hydor mounted to the side of my tank. Currently, the pump is actually closer to the top of the tank. The top of the tank just seemed like a better spot for the power head once the live sand, live rock, and saltwater were all in place. The location near the top of the tank also helps create some waves and turbulence at the air/water interface to help with oxygenation.
How do you circulate the water in your aquarium? Leave comments below.