You mentioned that you will be keeping the anemone under MH. I would suggest you use perhaps a 14,000K rather than the 20,000K listed in your posting. They are shallow water animals and prefer daylight. Also, don't be surprised if it takes it a while to adjust to two 250 watt MH. In transport or warehouse, it might have been under much less light than that. I personally have kept mine under PC's, MH, and now T-5's. Mine seem happier either very near the PC's (literally a few inches from the 6700K bulbs) or under the t-5 HOs. It took a long time to adapt to the MH (10,000K), which I kept them with for over a year. Some say that H. magnifica does best under MH, that hasn't been my personal experience, though I've seen pics of some under MH that were thriving. Just know, it might take yours a while to acclimate to a MH.