If you have ever ridden in a boat on salt water at night, you have seen the phosphorescent trail caused by the mechanical stirring of the water by the propellor. I have seen such phosphorescent wakes from aircraft as well - you see a large glowing green triangle that is brightest right around the stern of the boat.
On two occasions - one a warm tropical night on the South Pacific island of Guam, and once on Nantucket (a Northern island wrapped in the warm waters of the Gulf Stream) I have also seen such glows in the surf. I believe these are caused by phosphorescent plankton.
I find it entirely believable that a colony of such plankton could get established in a tropical saltwater tank in the sand substrate. I believe such will be very hard to photograph, because I have only observed these faint green glows on moonless nights.