Choosing an External Pump

Adding an external pump to your reef aquarium

by Brian Dunat

In the past, most of  all used some form of a submersible pump to cycle water from a filter or sump into our main display tank. What happens though when you cannot get enough water pressure out of a submersible pump or you have two tanks and you don’t want to setup another sump? Enter external pumps. Scared yet? Don’t be.

Planning for your new pump

External pumps will require some changes to your sump, but if it’s a new sump you are installing, most LFS’s will charge a small fee to pre-drill the tank for you. If you are adding an external pump to an existing sump, this will require a little more planning and work since you can’t really drill a tank that is full of water and in use.  In this case, it makes sense to drain the sump tank and then drill it. How do you find the right pump? The first thing to do is sit down and sketch out your plumbing plan.  I always like to come up with a drawing and then have other reefkeepers take a look and give feedback on what they would do differently. Once you know what the plumbing to all your tanks and reactors will look like, it is time to answer the following questions:

1. What is the maximum height your pump will have to push water too?

2. How many outlets do you want to have on your water line?

a. Outlets can be used with reactors (e.g. Carbon, GFO, Bio-pellet), UV Sterilizer, extra

tanks or main tank water outlets

For discussion purposes, we’ll use one of our ReefNation setups for example:

• Max Height: 20’

• 6 outlets (2 reactors, 1 UV Sterilizer, 2 frag tanks, 1 main tank)

Choosing an External Pump

Choosing a Pump Brand

When looking for a pump, there are many brands to choose from and many specs to consider when comparing them.  What is the pumps’ head pressure?  How many watts of electricity does it use?  What plumbing inlets and outlets does it use?  All of these are valid questions.  In our case, we have about a 15ft head that we need the pump to pump up so we chose one of the larger Pan World/Blue line pumps in this example, specifically the PanWorld 200PS pump. In checking their website (chart shown below), we found that at 20’ max head pressure, we will get 21gpm or 1,260gph. This is important to note because the pump actually is rated for 1,750gph, but that is at 0’ head pressure. When we figure in our max height, we lose nearly 500gph. This is why planning out an external pump is very critical to ensure you actually get the desired water circulation in your tank(s).

Plumbing Tips for Installing your External Pump

We will cover a full plumbing tips and tricks in an article here shortly, but here are a few tips for a successful pump installation.


Unions are plumbing connectors that allow you to quickly disconnect plumbing in the event you need to say get a snail out of your water line..  I like to put them just before and after the pump so if need be, it can be fully disconnected in a matter of seconds.

Check Valves!

Adding a check valve just after your new pump and union allows the head pressure of the line to keep the check valve closed in the event you disconnect the union or turn the pump off.  If you didn’t have this, imagine how fast your main tank would drain back down into the sump if say the power went off!

Overflow Strainers

Make sure you purchase an overflow strainer and fasten it to the feed for your main pump as the water exits your sump. This will ensure small debris and snails never get sucked in and lodged in your outlet or all the way in your external pump.  If you roll the dice long enough, this will 100% happen, believe me 🙂

We’ll be back soon to discuss redundant pumps, plumbing tricks and valves.