How many Powerheads

[Aquattro]

Each tank is different. You need to assess whether you're getting flow everywhere you need it. But not enough to agitate polyps. In my 75g, I ran 2 x Tunze 6100, about 3100gph each. Plus the return, another 900gph. My 180 has these plus two smaller tunzes, totalling about 10,000gph of flow in the tank. I could use more. SPS and a couple of euphyllia colonies.