Powerheads create all-important water movement which is critical for the overall health and well-being of our tank inhabitants.
Having good water movement and circulation in the aquarium keeps fish healthy and active while increasing dissolved oxygen in the water through surface agitation.
Good water movement is also important for the health of corals as currents help to wash away slime and waste matter which would otherwise accumulate and eventually smother them.
Powerheads | Laminar Flow Vs Turbulence
Laminar flow is the direct, jet-stream flow produced by powerheads that have a small nozzle for the water output. While the laminar flow from several powerheads is perfectly fine for fish-only tanks, corals do not appreciate direct flow.
LPS corals especially will close up, drawing their fleshy tissue in, giving them a shrivelled appearance. When constantly blasted with laminar flow, LPS corals are even known to have their delicate tissue torn away!
Corals prefer turbulent and random flow, with water washing against and around them in a dispersed fashion instead of a direct blast of water.
Creating Turbulent Flow With Powerheads
There are several ways that we can reduce the effect of laminar flow from powerheads:
- The easiest method would be to direct the powerhead’s water output nozzle towards the front glass of the aquarium. With some experimentation you will find the right height for the powerhead in the tank as well as finding the right angle for the direction of the output nozzle. We are looking for good water circulation while watching out for any adverse effects the flow might have on LPS corals and mushrooms. You might even try sprinkling some fine flake food or Cyclopeeze and see how they travel about in the current. This will reveal any obvious dead spots in the flow pattern in your aquarium.
- I’ve had great success by directing two powerheads at opposite ends of the tank so that their flow meets somewhere in the middle. The resulting flow is very turbulent but you need to ensure that there is a clear ‘line of sight’ between the opposing powerheads with no rockwork that might break up the flow in between.
- Powerhead mods were all the rage a couple of years ago. For around 15 dollars, hobbyists could purchase a mod kit for their Maxi-Jet powerheads which essentially replaced the small impeller with a much larger propeller while adding on a large output shroud for great water dispersion. The only drawback was that most of these mods shipped with a stainless steel propeller shaft which usually rusted or developed little pits in the metal that stopped the propeller from turning smoothly after several of months of use. Or you could do like I did and just saw off the pointy output nozzle of Maxi-Jets for a wider, more dispersed flow. The interest in Maxi-Jet powerhead mods seemed to wane once Tunze introduced their very affordable line of Nanostreams.
How To Choose The Right Powerheads For Your Tank Size
It is important to choose the right size powerheads for your tank.
Just ask any hobbyist who has made this mistake — too large a powerhead will cause corals to close up, while stirring up a veritable sandstorm in the tank!
Also, while LPS corals do not appreciate high flow, SPS corals on the other hand require strong, turbulent flow to constantly wash away slime and waste matter from their tissue to stay healthy.
I prefer to use several smaller powerheads pointing in different directions rather than one or two large powerheads. This allows me to position multiple powerheads around the tank, ensuring that there are no ‘dead spots’.
My current favorites are the Tunze Nanostreams, which are very affordable and come with titanium impeller shafts which are impervious to saltwater.
As a very general rule of thumb, your powerheads should produce turbulent, non-laminar turnover of at least 10 or even 20-times the volume of you main display tank.
For a 100 gallon tank for example, the minimum total turnover from the powerheads combined should be at least 1000 gallons per hour.
Cheaper powerheads usually come with a basic mounting kit with the option of either hanging the powerhead from the rim of the aquarium or attaching it to the tank wall with rubber suction cups.
Rubber suction cups are hard to deal with. They always seem to lose their grip at the worst times, causing the powerhead to fall onto the sandbed, blowing sand everywhere — especially when nobody’s home. Or they simply refuse to come unstuck when you want to change the position of the powerhead.
A far more elegant solution is to purchase mounting magnets for powerheads such as the Maxi-Jets. Mounting magnets, such as the Sure Grip powerhead magnets made by Algae Free, allow for easy positioning of powerheads anywhere on the tank walls.
Large Intake Powerheads Are A Danger To Cleaner Shrimp!
It has been my experience that powerheads with large intake strainers can be dangerous to cleaner shrimp! With their long antennae and curious dispositions, cleaner shrimp (Lysmata amboinensis) have a tendency to get sucked into the intake strainer of larger, more powerful powerheads if they wander too close.
But do not confuse this with the molted exoskeleton of a shrimp stuck on the strainer of a powerhead. While a cause of alarm for most beginning aquarists, the shrimp is probably safe and sound in a quiet corner of the tank, waiting for its new shell to harden before it makes a reappearance
At any rate, if you have cleaner shrimp and large powerheads, it is a good idea to wrap the intake strainer with plastic mesh fastened with nylon cable tie.
Powerheads | Routine Maintenance
Powerheads tend to get clogged with algae and calcium deposits over time and will need to be removed for a thorough cleaning. Once the powerhead is removed and dismantled, a hard toothbrush is very useful for removing hair algae and mulm from the powerhead’s impeller, magnet and intake strainer.
For stubborn coralline algae and hard calcium deposits, thoroughly soaking the powerhead in vinegar or acetic acid will be required. This is especially the case when the powerhead has seized up and stopped working.
Simply mix hot water and vinegar in a 70/30 ratio in a small bucket and let the powerhead soak for 24 to 48 hours, after which any kind of calcium deposit should just flake off. I usually clean one powerhead at a time, keeping the others operating in the tank so that my corals are not compromised by a lack of flow.
Powerheads To Create Surface Agitation
Directing one powerhead so that it points at an angle towards the water line creates surface agitation. Surface agitation increases the oxygen-carbon dioxide increasing oxygen levels in the water. This is especially important in fish-only tanks where the fish population in is higher.
Having more fish in the tank causes a depletion in dissolved oxygen and an increase in carbon dioxide. Active fish like tangs especially, will be the first to exhibit nervous behaviour by darting about the tank when there is not enough dissolved oxygen in the water.
What Are The Best Powerheads For Your Money?
Let’s cut to the chase — Tunze and Maxi-Jet are two of the most reliable powerhead brands out there. Bar none.
I have never had a Maxi-Jet or Tunze powerhead fail on me.
Which is more than I can say for some other major powerhead brands which seem to have a lifespan of about 2 years. One brand of powerhead I owned for about a year was causing my circuit breaker to trip because it had somehow developed a short, no doubt due to poor construction that caused the insulation to fail. And this was one of the other major powerhead brands!
If a Tunze or Maxi-Jet stops working, usually all it needs is a good soaking in vinegar to bring the powerhead right back to life. I have Maxi-Jets and Tunzes that are well over 7 years old and they still work wonderfully. Tunze also has a comprehensive range of replacement parts available in the unlikely event that anything should break.