How to Choose a Properly Sized Return Pump for Your Saltwater Aquarium
One important consideration to keep in mind is that these flow rates are the amount of flow you need going back to the tank. A return pump will typically need to pump water through 4-6 feet of plumbing and an elbow or two. This plumbing applies pressure to the pump and reduces the amount of water being delivered. This means that a pump rated for 1000 GPH will probably only deliver about 500 GPH back to your aquarium once it is installed.
This is why it is so important to calculate the head pressure of your plumbing and compare it to the flow chart of the pump you are considering.
To calculate head pressure, each vertical foot equal 1’ of head pressure. Each elbow equals 1’ of head pressure and finally every 10’ of horizontal pipe is equal to 1’ of head pressure. As an example, if you need to pump water 4’ vertically, through 2 elbows and a 10’ horizontal run, your pump will be under about 7’ of head pressure. (a diagram would be helpful).
Tubing diameter can also have a significant impact on flow rate. It is best to keep the return plumbing the same size as the outlet size of your pump. If you change the diameter of your plumbing, flow rates can be drastically affected. Now let’s look at a flow chart. Let’s say the aquarium is 100 gallons and you have calculated your head pressure to be 7’. Looking at the flow chart you will see that the Sicce Syncra 3.5, 4.0 and 5.0 all fall within the 500-1000GPH range that you need.
If you want to be conservative with your budget and have just enough flow, you can go with the 3.5 which gives 581 GPH at 7’ of head pressure which means you will turn-over the entire water volume of 100 gallons about 5 x times per hour. If you want a bit of extra capacity, you can go with the 4.0 or 5.0 which is probably the wiser option. The flexibility of using a bigger pump can come in quite handy if you ever decide to change your plumbing, add a media reactor, UV sterilizer or even a chiller.
One thing I have always told other hobbyists in regards to return pumps is that you can always slow down the flow of your pump with a valve but you can never make it push more water. Now that you know how to choose the proper size of pump, let’s move on to the type and brand of pumps.
For larger aquariums that 200 gallons or more, the Reeflo pumps are extremely popular. They move a TON of water and are efficient when you consider how much water they move.
If you are pumping water up from a basement or far away from a remote sump, the Iwaki pumps great options because they handle head pressure extremely well. These industrial-grade pumps also require very little maintenance and are extremely durable.
The downside is that these pressure-rated pumps run a little louder and a little hotter compared to flow-biased pumps like the Reeflo.
For small to moderately sized aquariums with minimal head pressure, smaller pumps like the Sicce Syncra or Lifegard QuietOne are your best option. Installation is extremely flexible as most of these pumps can be used both externally or submerged and easily adapt to PVC or flexible tubing. When plumbing any type of pump externally, remember that these pumps are NOT designed to ‘suck’ or “draw” water.
Pumps need to have flooded suction so a bulkhead must be installed in your sump to allow water to flow into the pump freely. Attempting to use a U-tube to have the pump siphon water from your sump or installing the pump above your sump water level is a very bad idea. In recent years, DC or direct current pumps have become very popular. In addition to being more energy efficient and cooler running, DC pumps operate using safe, low-voltage electricity and offer a variety of advanced control features.
EcoTech’s Vectra DC pumps include flow control and feed mode capabilities which are available on most other DC pumps. What makes these pumps special is the variety of additional smart features: such as active feedback, back-up battery compatibility, wave modes for closed-loops applications available via their control app, Mobius.
The Reef Octopus Varios DC pump is another exceptional DC water pump. These pumps are Apex Ready so you can connect the pump directly to your Apex for all the advanced Apex control/alert features. It also includes a float switch that be used control the pump based on water level and protect you against dry run.