I recently built a simple homemade Aquaponic System, it is flood and drain type, the growing bed "GB" is filled with gravels.GB is connected to the fish tank "FT", the later has a submersing pump on a timer. Water is pumped from the fish tank to the grow bed every half an hour and stays there for half an hour, then by gravity it goes back to FT when the timer goes off. Now I am cycling the system by adding small amount of fish food every day as a source of ammonia to encourage the colonization of Nitrifying bacteria in the system. I am planning to add goldfish soon and planting lettuce and basil as soon as ammonia level and nitrite go down to acceptable level. Please join me in discussion if you have any idea to improve this system. Cheers!