It probably only needs a bit of bleach to get rid of the algae. It's VERY thin and NOT caked on. It just needs to be killed. I could do the cleaning for an extra $3. I also have purple or natural toned rocks you can have. Minneapolis/St. Paul area only. It will be too expensive to ship. PLEASE don't comment unless you plan to get it. I don't want to have to get a bunch of notifications of people saying they wish they could have it. Thanks for looking!