Basic Temporary Pond Filter

I have a 1000L pond and am having real trouble with Green water but only have a fountain pump with a small filter block but it says its up to a 1500L pond...Can't quite afford a real filter yet but want to get a filter going...
 
My Idea is a plastic storage box with sponge filters in and using my pond pump to put the water in the top and drain through and trickle into the pond.