As long as they're not too deep nor too wide you can replace the contents every now and then and give it a good wash out. Often see people using black plastic on the inside but this can overheat and cause more trouble than solving any problems.
Thanks for your reply seagull. The dimensions are 26" high, 32" deep and 90" long. Someone said it's important to line it so algae won't come through. Not sure what to do.