Thanks Cliff great start...
My one was a simple fix for a big problem did some shopping about found a preformed pond then found a pond filter for sale in the local news paper ripped the guts out of the filter then filled it with bio media and had a sponge pr filter on the pump. Boxed it in to make it look nice.
Its in a very well insulated fish room I run 2 x 300 w heaters and it works fine. I have got a lid to stop fish jumping and this keeps the humidity down in the room.