Mark Martin on Remote Filtration
Mark Martin is the Director of Marine Ornamental Research at Blue Zoo Aquatics

Q: How do I set up filtration on an odd-sized tank?

A: "I actually get this question a lot," says Mark Martin, director of marine ornamental research at Blue Zoo, "and the answer is pretty simple--remote filtration.

"If you have, for example, a hexagonal or corner tank, where do you put sump-based filtration if a sump won't fit in the aquarium cabinet? When faced with this situation, some people choose to turn to HOB (hang-on-back) filters or even internal or undergravel filters, but few of these filters can do what sump-based filtration can accomplish in a saltwater tank over 40 gallons.

"The nice thing is that remote filtration is actually easier than you think, and it allows you to use all of the sump-based filtration components you want to use (e.g. protein skimmer, UV sterilizer, substrate reactor) but not have to worry about space directly under the aquarium.

"Remote filtration can be set up in the basement or an adjacent room so long as you add a pump that can handle the excess head pressure. Head pressure is the back pressure on the return line. To determine the head pressure on your remote filtration return line, you need to calculate how much 'lift' there is in the system.

"To calculate lift, first measure the distance between the return pump and the level of the return outlet(s) in the aquarium (if the tank has multiple returns, measure any horizontal plumbing as well and add it to the lift). Once you know the lift, estimate the resistance caused by any twists or turns in the return line. To do this, add 1.5 feet to the lift for every 90-degree bend. 

"Now calculate the back-pressure caused by any submerged returns by adding one foot to the lift for each return. Finally, if the return line diameter is small, add up to two feet to the final number, or if the return line is large, then add only one foot. The sum of all these numbers should give you a rough idea of the head pressure your return pump on your remote filtration will be facing.

"Once you have calculated the estimated head pressure, decide on your desired flow rate (how many times you will turn your tank over each hour), and then consult the pump manufacturer's flow curve chart to determine what pump will support your remote filtration set-up.

"The beauty of locating your filtration in an area remote to the tank is that everything else besides the return pump can remain the same as your standard sump-based filtration."