look for the 'natural, or daylight, or grow bulb' just in the regular bulbs. That one i listed as a gem? is good, you can do a google for it too and its on amazon and several other places, by mail though. If you buy it at the store the url takes you to, its only 3.25, lol. plus shipping :(
i saw one online at walmart, oh that grow one with the skinny bulbs in it, it said Kwhater, 3500k I think. That will work to, but you have to protect if from water splashin up on it.