Ive used one in a pinch before. The store was out of 5.0's and I had a cham coming in the mail that day. So I suspended the fixture about a foot above the top of the cage and used it for about 2 weeks. It didnt cause any issues but I hated the look of everything and found a 5.0 when the store got their shipment in. I dont have a uv meter so I cant tell you exactly how much more uv a 10.0 puts out over a 5.0