I was even thinking of using a Savio LivingPonds Waterfall, setting it on the edge of the pond and surround it in a mound and cover with rock. Would I still need a liner to go from the pond to the lip of the waterfall?

Hi,
What is the pond made of?
Is there some type of liner? Heavy or thin? Black?

Why do you want to put something on the bottom?
If it's a liner pond keep it as clean as possible.
I have bottom drains in mine.

If you want to put koi in your pond keep it as deep and as large as possible.

You can make filters out of plastic garbage cans. I have used Rubbermaid cans. Pretty simple but sometimes the pipe pieces costs a bit. Especially ball valves to shut off water flow.

I'll have to go see what the Savio waterfall looks like to comment on that.
I'm assuming that would be at the head of your stream, then the stream to the pond?

The pond is currently made of concrete. It has been full for quite some time even through the warmer months so I'm fairly certain they waterproofed it somehow. It looks the the previous owner tried to make an inground spa. I was thinking of just having the savio waterfall dump directly into the pond from the 22" weir and then having the unit burried and surrounded in some type of rock for aesthetics. It has an approximate 108" diameter with about 54"-60" of depth. I don't mind the depth so long as I will be able to easily view the fish. By filling the bottom I ment, maybe fill the inside with dirt/sand and then use a pond liner to fill the existing concrete and added dirt/sand on the bottom.

Spa? Not necessarily.
Do you have some kind of "jets" in the sides of the pond?Some koi owners put outlets/jets in the pond to create movement in the water.

I'm sorry. I'me a bit confused.
You are not wanting the pond to be as deep as it is now so you are wanting to fill it in a little then put in a liner for the entire pond?

If that's correct then yes, you can get dirt or sand to fill it in. You will need to make sure you put down an unerlayment before installing a new liner to be certain there are no rocks or other debris will poke thru your liner.
If you are buying liner I DO recommend getting the Firestone pond liner, 45 mil.

About the Savio waterfall...How long of a drop are you wanting between the wier and the pond water level?
You will need liner for that so the water doesn't just hit dirt and run out.

No jets in it. Other than that it looks just like a concrete spa. I was just worried about it being to deep to really see the Koi. If that isn't an issue I will leave it that deep. I just want a pleasent sound to listen to in the backyard, not a niagra falls effect. What would a good typical height be?

No jets? What did you mean when you said you thought the owners must have tried to make a spa out of the pond?

Mine has about a 2-3 ft. drop into the pond. It does make a nice sound. It also depends on the amount of water flow as to how it will sound and look.
We have a 3500 gph pump that pushes the water from our filters approx. 30 ft. to the top of our stream. So we are losing some water flow by it having to travel so far. If we ran the pump directly to the stream alone it would have a much faster flow to the stream.

A friend of ours has a waterfall with a drop of about 7 feet. They also have a huge pump behind it and the water noise is LOUD.

It really just depends on what you like.
Our stream has 3 different , tiny, waterfalls. Each only drops about 4 inches. Gives a nice splash to the water.

If you get your pond running and it cycles the water should clear and you should be able to see your fish just fine.
An online friend's pond is 12 feet deep and is crystal clear. But he's got the money to MAKE it that way.

Okay, that you. About the spa thing. It looks like the guy tried to mimic what a fiberglass above ground spa looks like but made it out of concrete in the ground. There aren't any kind of jets like a normal spa though.