We decided to build a pond in spring and I have some questions...

- I want to have some plants in there so I was thinking of putting aquarium substrate for plants on the bottom of the pond. since it is going to be a pond, I am not planning on putting anything on top of that substrate (like gravel or sand that I have in aquariums) - would that be OK, or not?

- was thinking of cleaning the pond by totally draining it before the frosts come (I have a few 1000 liter containers where I would put fish along with some plants and of course the pond filter). I am planning to use a pond foil - is it better for it to be covered with water during the winter, when there is no fish in there or not? (I don't want it tearing or anything like that)

- alternatively if I decide to leave the fish overwinter in the pond - what should I do with the filter to preserve beneficial bacteria? How deep should a pond be - the place where the pond will be is quite cold in the winters (-20C)?

-If I overwinter the fish in the pond should I do the drainage cleaning in the spring? I plan on leaving the plant substrate in the pond, just taking out all the water to remove any other debries that fall in the pond.

-Of course I will do regular maintenance on that pond as I do in aquariums. It is just that in aquariums you don't get leaved, dead bugs and stuff like that falling in

- what filter would you recommend - I still don't know how big the pond is going to be, I just want to knw what brand you recomend. I have eheims for aquariums