A crucial part of keeping a reef tank healthy is having the proper amount of water flow in your tank.
The keywords being proper amount.
It is definitely possible to have too much flow in a reef tank. In fact, having too much water movement is a common mistake which is problematic for any saltwater tank.
The same is true for not having enough water flow. This can be a huge problem as well.
In order to maintain a thriving reef tank, you need to ensure that the water flow rates match the demands of your tank.
In this article, I will show you how much flow you should have in your reef tank and the problems of having too much flow.
Why do you need water flow in a reef tank?
Water flow in a reef tank serves many purposes.
- It promotes gas exchange and increases oxygen levels.
- It decreases carbon dioxide and maintains PH levels.
- Important for the growth rate of corals.
- Water flow brings food and nutrients to the corals.
- It keeps corals clean by removing waste from around the coral.
- Water flow is important for fish health.
How much flow should a reef tank have?
Proper flow rates for a reef tank will depend on the types of corals you plan on keeping and the other fish and livestock in your tank.
Certain fish don’t like strong water flow and others do. A good example is the Copperband Butterflyfish which does not like water flow.
Just the opposite is the Clown Tang which loves strong water movement.
If you have too much flow in your tank with fish that are sensitive to water flow, you will have unhappy and sick fish.
The amount of water flow also depends on the coral types you are keeping. Corals like SPS and LPS require more water flow than soft corals.
A general rule of thumb is to have a 10-20x turnover rate for soft and LPS corals and a 20-30x turnover rate for SPS. Sometimes higher depending on the corals.
This is the number of times the entire water volume of your tank is moved. Measured in gallons per hour (GPH).
For example, you may have a 100 gallon SPS coral tank and plan to have a 20-30x turnover rate. You will need to have a wavemaker capable of producing 2000-3000 GPH.
Certain SPS corals like Acropora require strong water movement and you may find that you need an even higher turnover rate.
Can SPS have too much flow?
Talking about the turnover rate and water flow, it is possible to have too much water flow even for SPS corals. They are known to handle strong currents but there is a limit for all coral types.
Overdoing it is not a good idea and will cause serious health problems for the coral. Also, strong water flow can cause sand and other debris in the tank to cover corals causing stress and possible death.
Having a strong flow rate above what is considered normal for SPS corals will be a problem.
Read 7 SPS corals that love high water flow here.
How to tell if you have too much flow?
One easy way to tell if you have too much water flow in the tank is the corals will not open up properly. They will usually stay closed up.
You may also notice parts of the coral peeling or fading in color. Any corals that are not showing polyp extension or parts of the coral are dying could be a sign of too much water flow.
Creating proper water flow
There are 3 main types of water flow you can have in your tank.
- Laminar
- Pulse
- Turbulent
Laminar flow is basically having a constant stream of flow at the same rate. This is usually aimed at the same direction by using a powerhead.
It’s important to never point a powerhead directly at a coral. Even if you have a laminar flow, you can aim it away from the corals and around rocks to create a more varied pattern.
Pulse flow is similar to a laminar flow only with different rates of pulsing water that is increasing and decreasing.
Turbulent flow is the random flow of water in many different directions. Wavemakers are great at creating a turbulent flow pattern in your tank which is the most beneficial for your corals.
Read: What size aquarium wavemaker do I need?
Summary
If you currently have a reef tank or plan to have one, it’s important to know that you can have too much water flow. Some people will run their SPS coral tanks at very high flow rates.
It takes a lot of time to acclimatize your corals to a very high flow rate and it can be very difficult. If you follow the recommended flow rates for the coral types you are keeping, the chances of keeping them healthy are greatly improved.