thats the one i have also. also from txhydroponics. I just fgot it home today and was under the impression is was closer to 5x5. wrong. it actually just barely over 4x4. I was hoping for this extra foon b/c i want to use an ebb and gro system that is expandable. I'm thinking about returning it and getting a 6.5x6.5x6.5. what light do you have for yours?