Btw I have found an old mh bulb that I'm just in love with to display these clams and they are doing great. I have found that you need plenty of par and white light as well as blue for these. I had ushio 14k in there and they responded great but I can't stand the bulb. So now they are under old aquaconnect 400 w hqi bulb 14k. Wow. I'm going back to this bulb in other tanks. So much more natural than radiums I think and it has the violet that radium misses. I'm trying to get these from Germany now. Will see.