I am considering way down the line a saltwater outdoor pond that will keep a few "hands on" critters for the kids to pick up and abuse. Star fish and urchins come to mind. My thoughts are that the lighting would be simply sun light from above. I could heat in the winter and maybe cool or shade in the summer. A small pool pump would circulate and one of many rubber maid containers could be a sump/filter. A DIY protein skimmer of large scale would be designed. I was thinking of the clear panels used in green houses to maybe put over it to keep out rain water in the summer. I cant find any info on this anywhere. I am trying to avoid a stinking pond full of green slime. Any thoughts? Anyone done this? Maybe 10ft by 20ft with a beach area tapering down to 3-4 ft deep was my plan. Thanks