System Sizing

[Don Gibbs]

Hello All, I am in the planning stages for setting up a raft/DWC system. My other system is a flood and drain type. Can any one tell me if the same rules apply for both when it comes to tank/bed ratio. I have watched clips from Murry's video that stated you need equal amounts of volume from tank to bed. I have a 100 gallon tank but have not purchased my beds yet. The beds I was looking at are 25 gallons per bed. Also, I read some where in this group about Polywall from Home Depot, but can't find a listing on their website when I do a search. I am interested in this due to the fact that from reading posts, some people are having their foam rafts degrade over time. Has any one got any ideas on alternatives to rafts than these two. Thanks for any help sent my way.