Let There be Flow!


Everyone who owns a fish tank knows that you need a light, some sort of filter and a heater/chiller. These are some of the most common things needed in an aquarium and most beginners already know they need these three aspects. I mean its common sense right?


But what most people don’t know is that a crucial aspect of a marine aquarium is the flow of the water within the display tank. Good flow around the display tank is essential for coral health, the oxidization of the water and it prevents waste from building up on the rock or floor of the tank.


This is where a wave maker comes in handy…



When I say good flow, I don’t mean flow so strong that the water in your aquarium splashes around and your fish look like they are in a thunder storm. Have you seen Finding Nemo? He didn’t do so good when he was in the bag been shaken up by the little girl. That was way to much water movement!

You need just the right level of flow. Basically all we are trying to do is to mimic the ocean waves. Everything we do to keep saltwater critters revolves around trying to mimic their natural environment as much as possible and a wave maker is an essential part of equipment that allows us to do just that.

So before we get into details about what a wave maker is, lets talk about flow…



# Basics of Flow


One of the most under-rated things to consider when setting up a marine aquarium is flow. Water movement is essential to maintaining a healthy aquarium.



One of the biggest purpose of good flow is to prevent detritus build up. With enough flow, detritus is not allowed to settle on the substrate of your aquarium. If this is allowed to settle it will rot and decompose resulting in a spike in nitrates. By keeping the detritus in the water column it will be picked up by your filtration such as filter socks. Regular cleaning of the socks will remove the waste from the water column.

In fish only with live rock (FOWLR) and reef systems having ample flow becomes even more important. Due to the live rock being the main filtration in these types of tanks flow to get water to the bacteria is very important. An even higher flow rate than is needed to keep detritus moving is recommended when using live rock as filtration.



# How Much Flow


The Flow is rated in total tank turnovers per hour. This is the amount of times the total tank water volume is run through your pumps/wave makers per hour.


There is a basic equation for this;

Total flow of the pumps/wave maker ÷ Total tank volume

For example, If a 20 gallon tank had one power head pushing 100 gph (gallons per hour), then the equation would be;

100 ÷ 20 = 5

So the overall tank turn over per hour is 5.


# FO tank flow – FO (Fish Only) tanks generally need the lowest flow. From 15x turnover to 20x turnover should be enough flow to keep detritus suspended.


# FOWLR flow – FOWLR (Fish Only With Live Rock)  systems will need more flow to get water to the filtering bacteria. 20x turnover is a recommended minimum.


# Reef flow – Reef tank flow will start out at the same FOWLR guideline of 20x turnover, but depending on coral type this could be all the way up to 100x turnover or more.


Low flow (20x-30x) – Several types of corals do very well in low flow conditions such as: zoanthids, palythoas, some leathers, most large polyp stony (LPS) and many others.


Medium flow (30x-40x) – Most of the corals from the low flow group will also do well in medium flow. Medium flow also adds a few very fast growers such as xenia and more species of leather coral.


High flow (40x-100x+) – Some of the low and medium flow corals will do ok if placed out of direct flow up past the 50x turnover mark. Corals from the medium flow group such as: xenia and leathers will still thrive in high flow. Fleshy LPS will have to be placed in a relatively dead spot to survive in a high flow aquarium. 50x+ turnover introduces a whole new group of corals known as small polyp stony (SPS). SPS coral needs very high flow to keep its polyps clear of waste.



# Types of Flow


FO and FOWLR tanks will do well in most types of flow as long as there is enough. Reef systems however demand more chaotic flow to keep coral healthy and growing.



# Laminar Flow – Laminar flow is unidirectional. You will usually end up with this type of flow when you have only one source of flow.


# Alternating Flow – Alternating flow is most comparable to a wave motion. The water pushes forward then back in a rhythmic motion. This is the type of flow you will get from a wave maker or some timers.


# Random Chaotic – Random Chaotic flow is usually the best choice. It is easily achieved with the use of several power heads pointed to converge in the tank.


Information taken from Mikejrice at 3reef


.. and what produces flow in an aquarium? A Wave maker.



What it is?


Wave makers are literally… wave makers. They are water surge devices that produce waves within the aquarium. The overall goal of this is to try to re-create the same conditions found within the oceans.



What is does?


They Basically produce flow within the aquarium. Yes, that’s it, but its an essential aspect of a tank.

Once you have an understanding of what flow is and why its important in an aquarium all you need to really know are two key points;


# 1

That each wave maker is different and produces different types of water movement depending on what setting you have them on.

Some wave makers have settings that allow you to change the type of flow in the tank (The types of flow explained above). Each reefer is different and has a prefer type of flow they desire in the aquarium.


# 2

The Goldilocks rule. You need just the right amount of flow, not to little and not to much (See How Much Flow above)

The combination of 1 and 2 is all you need. Its all I really know if I’m honest.

If you have a small tank a small wave maker will do, if you have a large tank you will need a few wave makers to produce enough flow. You can use many small ones in a large tank or a few large ones, its totally up to you as every aquarium is different. Something as simple as the layout of the rock in the tank can determine how many wave makers you will need and where to place them.



# Commonly Asked Questions – Wave Maker Placement?


This is a hard question to answer without seeing your set up. The size of your tank, the shape of your tank, the rock layout and coral placement are all factors that are a part of wave maker placement. You want to eliminate as many dead spots as possible and ensure there is enough movement on the surface of the water while making sure the corals get the flow they need.


TIP – Its a case of working with your return pump and planning out the best fit for your system. I think the most common placement that I have seen in home aquariums is on the side wall of the tank opposite the return pumps flow.



It is for the above reasons that make it so difficult to give advice on wave makers. Each tank setup has a unique flow pattern so their is no one correct method.


The only thing that goes for all marine aquariums is that a wave maker is an essential piece of equipment and flow is a must!



Why it is needed?


A wave maker is needed to produce flow within the aquarium. Nothing more, nothing less. Its a simple reason but its also an essential one.

There are many advantages to having a wave maker in your aquarium. They far out weight the disadvantages of having one as the only negative aspect I can thing of is the little noise they make and the little space they take up in the aquarium.



Many of the advantages are;


  • It helps keep the fish healthy – In their natural habitat the fish and inverts are use to constant water movements as the waves don’t sleep. To mimic the fishes natural habitat a wave maker is essential.
  • Prevents dead spots – A dead spot is a place in the tank where there is low/no water flow. As a result of this waste, detritus and left over food gets left in this section of the tank. Over time it builds up and rots, resulting in poor water quality. No dead spots = no waste build up = better water quality. Its that simple.
  • It keeps coral and inverts healthy – Many coral and inverts don’t move around the aquarium. They need the water flow to bring food, nutrients and oxygen to them. If you want to keep them healthy and alive then good flow is essential.
  • They add to the over all visual appeal of the tank – flow causes corals to sway like grass in the wind, it stimulates fish to become more active and gives the aquarium an overall natural look.


Overall its fair to say that no reef tank is complete without a wave maker and they are now a must have in terms of essential equipment.


I hope you found this information helpful. Think we missed something out? let us know!