While many return pumps can produce a lot of flow in the tank itself, it is important to check if the flow is strong enough for the size tank you have. There should be no dead zones which means flow should hit every inch of the inside of the tank. This is where powerheads come in very handy. There are many options that vary in price and quality and can also be used to create the ideal flow in your tank. 

We like to imagine the flow like how we like the wind outside; enjoyable where we can feel it, but not violently blowing. No coral or fish would enjoy a violently strong, direct current and you probably wouldn't either. Instead, most prefer a gentle to moderate, often alternating flow, never direct. Even SPS corals that prefer high flow do not enjoy direct flow straight from a powerhead or return nozzle.

 

In large tanks (50+ gallons), we highly recommend gyres because they have a long bar of flow allowing more surface area to be covered as well as breaking surface tension which is important for oxygenating the tank. Many of these powerheads allow you to adjust the flow so that it can blow forwards and backwards and create a swaying motion rather than pushing in one specific direction. This is very helpful in reducing dead spots where nitrates can build up. 

For tanks smaller than 50 gallons, there are a lot of great small powerheads that offer similar features. We always recommend ones that allow control of speed and direction.