The answer to all ur questions is yes, i will have a bed of sand, the ocean motions will have a 45 degree angle, 2 and 1/2 inches above the sand bed behind the rocks. there will be one tee with two locklines, 3/4 inch from each hole. each lockline containing a 3 inch nozzle, hopefully i will not get sand in the oceanmotion, the reason i went with 2 seperate systems was due to maintenance, one will always be running while the other is maintained, hopefully this will work no one said it would be easy.