I thought it was the other way around, the smaller clams require the more phytoplankton, and the larger clams more light, at least is what Dr mac said. I think the clams they have are a great selection to other places. They have a huge selection and the nicest clams I have seen. They care for the clams before selling and clean them and acclimate them for awhile. The price compared to other places is great. You can either take off $25 on the price or get $25 in live stock. Shipping is lower than alot of other places. There shipping is great. they called to confirm you get it and they triple bag and include a ice pack.