I've had my tank running for a few months. 55 gallon with about 40lbs of rock. My Sand is starting to get red/green/purple patches. Under top layer. I asked LFS
. They say it algae from dead spots, meaning waters not circulating enough! I have 2 650 koralias. I had them on opposite sides. One pointing slightly to the back and upwards. They other pointing to the front slightly down. What is the best positioning for full circulation. Some say it creates a vortex type flow! How do u know when u get full circulation?? Any help and pics would be appreciated!!!