Algae problem

[sage2000]

I’ve been getting algae on my sand bed and am wondering how to stop it. I’ve had my tank for around 3 years. I do a water change and clean the sand bed every month. This stuff pops up right after a few days later. I wonder if it’s just from over feeding or if there’s something I can add to reduce it. There’s also a red spot that I’ve noticed on one spot on my live rock. I’m not sure what that is and if I should do something about it. Any advice or knowledge would be appreciated.

 

[Cali Reef Life]

Increase the flow or get some CUC that move the sand around or a goby.