Hi everyone! I'm new here and am setting up my first small scale aquaponics system. It consists of a 18 gal. rez, and two 8 gal. growbeds. Obv. The rez isnt filled all the way, but its close. I just ran the water through the system to make sure everything is working before I add the hydroton. The water gets very low in the rez and I was wondering if thats ok for the fish. I plan on getting 15 goldfish (about 1fish/gal??). The cycle is like 10 grow bed fill, 5 min siphon. Is this ok? Or will the fish die or something?