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A Guide To Increasing Water Flow Inside Your Aquarium

by Brian Dunleavy
A Guide To Increasing Water Flow Inside Your Aquarium


Do you frequently have poor water quality, sick fish, or an issue with algae? These are indications that your water flow is not powerful enough. 

Water movement is essential in maintaining fish health in saltwater aquariums. Ensuring you have good water flow also benefits aquatic plants, corals, and live rock. There are many ways you can increase the water flow inside your aquarium, which we will outline in this article. 


Why Is Water Flow Important For Aquariums?

As briefly mentioned above, water flow is key for aquariums to maintain good water quality and healthy fish.

Water movement oxygenates your aquarium, so providing enough water flow is critical in ensuring your fish has sufficient oxygen to beathe. 

Another benefit of good water flow is maintaining the aquarium’s internal temperature. In aquariums with poor water flow, areas of cold and warm water can form. Circulating the water by increasing the water flow will prevent thermal layering, which is particularly common in larger aquariums. 

Lastly, poor circulation also creates dead zones, where debris like uneaten food will collect. Directing water flow to these areas will prevent a build-up of debris that can affect the beneficial bacterial colonies inside your aquarium.

Aquarium Water Flow Rates

When people are purchasing water flow equipment, we often get asked how many gallons per hour (GPH) of water flow is required for their aquarium. 

Gallons per hour or GPH is the unit used to measure water movement in aquariums. Once you know how many gallons your tank holds and what type of aquarium setup you have, you can calculate the GPH. 

For example, if you have a 75-gallon fish-only tank that needs to be turned over 5 times an hour, you will need a pump rate of 375 GPH (75 x 5). 

We typically recommend that you turn over your aquarium volume 5-10 times per hour for a saltwater fish-only tank, and 10-20+ times for a saltwater reef tank. That being said, we recommend aiming a little higher than you need and observing how your marine life copes with the water flow. 

Equipment To Increase Water Flow

There are four main pieces of equipment to increase the water flow and circulation inside your aquarium:

  • Water Pumps
  • Powerheads & Wavemakers
  • Air Pumps & Air Stones
  • Filters

  • #1: Water Pumps

    Aquarium Water Pump

    If you want to increase the water flow inside your aquarium without creating strong currents, a simple water pump will solve your problems!

    Water pumps are perfect for increasing water flow and circulation inside aquariums, particularly larger tanks. 

    We recommend buying two less powerful water pumps in case one of the pumps malfunctions, you won’t need to worry about your water flow while you buy a replacement. Water pumps are commonly combined with powerheads to provide directional flow and water circulation at the same time. Not sure what a powerhead is, read on to find out!

    #2: Powerheads & Wavemakers

    MP60 VorTech Aquarium Powerhead

    Powerheads and wavemakers are small, but they are fantastic at producing laminar or unidirectional currents inside aquariums. 

    They are relatively inexpensive, so many hobbyists will buy two or more, placing them in different locations to replicate currents and ocean turbulence. Powerheads can also be attached to wavemakers which create random alternating currents inside your aquarium. This type of water flow is best in reef tanks. 

    When installing a powerhead, it is important to never aim them at popular fish hang-outs, or directly toward invertebrates or corals that cannot withstand strong water flow. When the water flow is too strong, it risks tearing coral polyps and encourages invertebrates and fish to hide. 

    #3: Air Pumps & Air Stones

    Aquarium Air Stone

    Air pumps and air stones are not specifically designed for water circulation, however, they do provide water movement. They do this by creating bubbles that break the water’s surface tension, encouraging gaseous exchange, and therefore, increasing oxygenation. Air stones are also used during power outages or when a filter clogs, which can save your fish’s lives. 

    The downside of air pumps and air stones, is the amount of volume they target. Air pumps and air stones cannot provide your entire aquarium with water movement. This is probably why you have noticed the lack of GPH ratings on the side of air pumps and air stones. 

    So, if you have an aquarium that holds less than 50 gallons, an air pump and air stone will work well. Tanks larger than 50 gallons will need a water pump or powerhead to circulate the water and oxygen.

    #4: Filters

    Aquarium Filter Pump

    Filters achieve very good circulation in smaller aquariums, particularly in quarantine and fry tanks. In larger saltwater aquariums, they can be used, but they are best coupled with powerheads to increase the water flow. 

    While filters are great, they do require regular maintenance to clean and replace the filter media, and the inside of the filter and tubing every couple of months. 

    There are many different types of filters available with different flow rates, so check the GPH of the model before buying. Typically, external or HOB (hang-on-back) power filters and canister filters have the greatest GPH rating. 

    Where To Position Powerheads?

    Powerheads are the most popular way to increase water flow inside aquariums, and they are best placed near the top of the aquarium. Remember, when positioning powerheads look for any dead spots that need dispersing. 

    Aquarium pumps placed too close to the bottom tend to stir the sediment, resulting in cloudy water, which means you cannot enjoy your epic display!

    You may also consider placing the powerhead near your heater if it has a low flow indicator that always goes off. Placing the powerhead near the heater will evenly spread heated water to prevent thermal layering. 

    If you want to place the powerhead out of sight, you can block it with aquarium plants or an aquarium ornament, or you can opt for a black background, so it blends in with the back of the aquarium. 


    Good water flow, tank water turnover times, and water movement are essential for aquariums to function. To increase the water flow inside your aquarium you can add a powerhead, air pump, filter (hang-on-back filters are best), or a water pump. 

    If you need help with aquarium maintenance, reefing supplies, or maybe your next mesmerizing coral, contact the Reefco team, or visit us in-store. We are always happy to assist you with any aspect of your aquarium setup!

    by Brian Dunleavy