which the best way to build a pond?

Hi! We bought a house with a 5000 gallon koi pond.... They had this
huge box that they used as a filtration system and used 2 pool pumps
for the pond (one for the pond and one for that box) When the
previous owners came to get some fo their fish, they installed a
waterfall, cut off the big filter box and just left one pool pump
running. THey also had a trough in front of pond filled with gravel
and a pvc pipe running thru it. Over the summer that pool pump broke
so we bought a pump that linked to the waterfall and also bought a uvc
lamp to cut down on the algae. I am still having alot of problems
with algae.... I have to clean the pump and waterfall out several
times a week.

Since we did not like where the pond was located we decided to move
it. We are still in the process of doing that. My husband has been
looking at different ways of doing the pond. Like, in addition to the
waterfall and fountain adding a skimmer. We visited a farm up the
road and they use a system that had a separate part filled with pea
gravel and the bio filter. their water is crystal clear. From that
part (the gravel pool) they have a stream running to the pond, they
have lines that make a water fall with out extra skimmers.

Its hard for me to explain the system that this plan t famr used. It
was like they had the pond with streams leading to it that connected
to a gravel pit that looked like a little pool (with plants in it)
they also made waterfalls from hoses and it really lookedgood. and
like I said the water was clear.

Another question, until I can get a generator, the fish are basically
dormant in the winter, I heard we should keep the fountain going.
Where I live, we lose our electric alot in the winter, will the fish
be safe?

Should I be feeding them a special feed until the water temp hits 50
degrees? I hear so many different things I should be doing. Like,
don't feed them when the algae builds up, feed them 2 times a day.
Those damn fish hear me walk on the deck and they are swarming for
food...lol


thanks for any advice