Hourly.
I trim the cabomba every week, and thats as long of an interval as I can get away with on it. The Giant Hygro and Red Wendtii about every two weeks.
Recently ( in th last few months ) I realized I had to much light. If you remeber when I built it I put 6 39w T5 HO's over it. I cut back to 4, it still alot, but its not crazy.
Went to the wholesalers yesterday. APet, the biggest in the midwest. Got a couple Twig Catfish, some botia I've vever seen before, and a couple plants. And smore more of those snails that I like more then they like me. Zebra Nerties.