New project!
Fish pond from cold water tank
This project was started on monday July 30th and finished on Thursday 2nd August. The tank cost �43 from local plumbers, same tank from aquarist shop was �68!!.As it was fitted next to my first tank(18 inches away), I mounted it so that the water would be 3 inches higher and fed the overflow from it into the smaller tank. 3 inches of small pea gravel in the bottom and the overflow fitted, I filled it. It promptly sank down another inch and ruined my cement edging, which had to be repaired. (Moral: make sure soil is compacted better).
The tank has ridges in the base for strengthening and these make a good support for a glass shelf to take the pond pump (�3 from local boot market) which drives the feature. another �2 pump I reconditioned, pumps from the small pond into the greenhouse,
through a cannister filter (boot sale! ) to a drilled out plastic statue (you guessed!) giving through circulation via an overflow.. 
The overflow pipe is cut to keep the water at the desired level and a plastic lid drilled to fit on it open end upward, with a ring of holes drilled UNDER the water level, so the the overflow does not take water from the surface.I first tried a piece of sponge but it blocks up too quick
A plant drip tray was purchased from a "pound" shop and found to be an EXACT fit into the tank, resting on the first of the ledges resulting from the stepped sides of the tank, ideal for putting the plants or lilies on in pots!. Covers were made for both tanks from1 X 1/2 inch wire on frames to keep out birds, leaves , cats etc.
It now contains 4 shubunkins, 5 comets, and three golden orfe, plus much plant material from the little pond, which seems to grow plant like mad!. I have had one calamity as one of the goldfish twice tried to commit suicide by jumping into the water inlet and missed it the second time and landed outside on the garden where he/she perished. I found it the first time and rescued it but it was set in its ways!.
Hope this interests you and maybe gets you going on a pond. Lot easier to keep than a big one!!
I have since had another calamity in that one of the fish, a shubunkin caught his head in the reeds and tore off a gill cover! Afraid he died after treatment. Reeds removed from pond and put in surrounding soil. Another lesson learnt! Pond and fish all well (October 26th)