Saltwater Aquarium Return Pump Q&A
Commonly Asked Questions about Pumps in an Open System
This article answers some questions about setting up a return pump for a marine tank connected to a Berlin-style sump.
Does it matter where I mount my return pump? Because return pumps are made to push water (not pull it) the return pump should be mounted as close to the sump as possible and below the water level (although not submersed unless it is a powerhead (submersible) pump).
Do I need to install a ball valve on my return line between the return pump and the return outlets in the tank? While you do not need to install a ball valve on the return line, it is recommended by many experienced aquarists that you do. Having a ball valve and a union (or a true union ball valve) installed in the return line directly adjacent to the return pump allows you to:
- Regulate the flow rate in your return line.
- Easily isolate the pump from the system water in order to remove it for maintenance, repair or replacement.
Should I place a ball valve on the pump intake? You should absolutely NOT place a ball valve on the pump intake for the purpose of limiting the pump’s intake. Placing a ball valve on the pump intake will not harm the pump in and of itself, but if you were to limit the pump’s intake with the ball valve, you risk damaging your pump. If your return pump is an external pump plumbed to the sump with a bulkhead, you will most likely want to install a ball valve and union on the line between the sump and the return pump. The ball valve should only be used to shut off flow to the pump AFTER the pump has been unplugged. Thiis set-up allows you to easily isolate the pump from the system water in order to remove it for maintenance, repair or replacement.
Should the diameter of pipe feeding the pump be the same as the diameter of pipe leaving the tank? To avoid cavitation, your inlet pipe diameter should generally be the same diameter (or larger) than the outlet pipe diameter.
Do I need to prime my pump? Most return pumps MUST be primed. Running a pump while it is dry is very risky and almost certainly will result in damage to the pump. Priming the pump means making sure that water is in the pump before it is plugged in. This can be accomplished if it is connected to the sump with a ball valve that can be opened after the pump is connected, allowing water to flow into the pump.
Does using multiple pumps in parallel increase flow? Mounting multiple return pumps in parallel or in series does indeed increase flow without increasing energy consumption to the level that a single larger return pump would.
Does "valving back my pump" really save energy? Is it bad for my pump? While it is rare to be concerned about too much flow in many saltwater systems, if your pump is performing well above your desired flow rate, you can limit the flow on the outlet side of the pump with a ball valve to produce the desired flow. And yes, this will indeed reduce the return pump's electrical usage.
Read other marine aquarium articles by Ret Talbot.
