Hello.
I'm new member and it's my first post so please forgive me if this is an inappropriate place to ask this question. 
I have an old glass aquarium. It is quite small (45, 30, 31 cm) and I was thinking I would like to turn it into a small pond/water garden.
However I'm not sure if it would be appropriate or where to start. My idea was to partially fill it with some substrate, probably a gravel beneath soil of some sort. Add stones and plants and wait for nature to do the rest. I had also considered painting some of the sides black to cut down on too much light promoting an explosion of algal growth?
Although I have experience keeping tropical fish, I have no real experience growing water plants, especially outside. So what I would like advice on, please, are the following points...
Suitability of aquarium in the first place.Substrate options. Species that are the best to use - clearly the point here is to encourage as much wildlife as possible so presumeably natives are the best option. Is painting a good idea or even necessary? Position - I live on Anglesey and my garden is south facing. So, it's either blistering sun (when we get any sun) or fairly hard shade, with few inbetween areas. Also subject to heavy rains and fierce winds (and I do mean fierce). Winter weather is cold and wet but hard frosts and snow are uncommon.
Sorry to go on, I'm trying to supply as much pertinent information without writing an essay.
Any help or advice no matter how small would be most gratefully received.
Very many thanks in anticipation.
D.