New Tank

Hi there, I'm new to saltwater and new to this site. Have a 46 bow front tank and workkng in a fish only set up. Been cycling the tank for 4 weeks with no fish and using food evey day to help seed. Under direction from my local fish store, I have 35 pounds of dry rock and 5 pounds of live rock and a crushed aggrogate base. Was told that I would see an ammonia spike and drop when the cycle was complete and still waiting, but have a burst of brown algae growth on rocks and substraight.
pH is at 8.2
Ammonia is about 0.25pp
Nitrite is 0ppm
Nitrate is 5ppm
I test the water every 3 days, did I miss the Ammonia spike and Is the tank cycled, or am I still waiting?