Let's talk about perfecting water flow in a reef tank!

[M4sonic]

This might be a real caveman solution, but i have a long thin stick with a small rectangular piece of thin plastic bag that flutters in the flow.

Great way to visualize flow in the tank.

 

[UtahReefer]

Perfect flow??? Tough assignment... Over many years I've learned that it's not so much the power head or the rate you're pumping out, but the tank and aquascape are a large factor. Many years ago we used to pile up rock along the back glass. put a powerhead on each side and blast it. Thank god we've graduated from that. Tank shape, aqauscape design, and pump position and flow rates all work together. Best indicator of successful flow? Still think it's dead spots. If your corals are happy but you see detritus building in certain areas then you have to solve for this. My recent effort (100EXT, transfer from my old system) was designed with flow as the primary consideration.

I built the aquascape on pedestals, in other words, there are three main structures that rock pedestals were built for that allow water to flow underneath. There are three pumps, a Nero 7, Nero 5, and a Gyre. The Nero's run in random mode, the Gyre is on constant running at 70%. With that I have about a 65-70% hourly turnover rate for the system. There's a lot of flow, but nothing blasting the corals directly. It took almost 2 weeks to figure out the rates and positions of the pumps to not blast the sand all over the tank. Even with this, I have one little spot (about 1.5" x 1.5") on the far left side that is behind a pedestal where I can see a slight detritus build up at times. For now I solve for it by just blowing the area with a turkey baster. Long term I'll probably put a small flow pump pulsing at that area. Corals are happy, good polyp extension. Sand bed remains clean so I'm happy.

So that's what I've learned over the years. Tank shape, aquascape and pumps all are the factors to achieving good flow throughout the system,. Hope this helps.