New to ponds, need maintenance help!

I am very new to ponds. My wife and I purchased this house which already had an estimated 1000 gallon pond installed in the back yard (see the attached photos I took last summer). I am not too sure how to maintain it properly and keep it clean. Also what to do during the summer. There are 2 waterfalls as seen in the "overallpond" photo. The upper pond is fed by the fall and the lower pond is fed by the river and another fall from the patio above. The pump is in the lower pond with a sponge that I wash off once in a while. The pond has autofull however it seems to always be running. It seems as though I have a leak somewhere in the pond, any suggestions or is it just major evaporation? I also get excessive algage forming, what is recommended to control that? There is underwater lighting and no fish.

Any help is apprecited!

kitokatlin

hi kito welcome to the site..you got a nice pond it saved you a lot of work, is the sponge your only filter, just how fast is your autofill running, you have no fish now , but are you thinking about them

I have been thinking of adding some very small Koi. Yes, the sponge is the only filter that is currently on the pond, it is part of the pump box on the lower pond. I know it saved me a lot of work! The autofill is on the same line size as an icemaker and is running probably 50% of the day. Quite a few gallons of water. What I am thinking I may do is drain the pond this year (the ponds are frozen right now) and cleaning the whole thing out, letting it dry and checking for tears in the lining. I am also looking to see what I need to do during the winter to keep the koi alive.

hay kito when you drain the pond down check and see what they did at the seams for your stream , what is the linner made of ? take a pic of your filter box . a uv light will help with some of the algae , and some filter work will get the rest