I was up to twelve 40-watt tubes, and finally switched to HPS ... I miss some things about the flouros, they grow nicely ... but, I stayed with the cheap everyday tubes ... my arithmetic always told me it was much cheaper to add an extra cheap bulb or two to make up the lumen difference, than to replace those high-dollar T5s, which tend to be pretty pricey, dollar-to-lumen-wise ... just something to ponder, do the math ... :smokin: