Ponds and Water Gardens - Waterfall/pond maintenance

I bought a house last year that has a waterfall and pond in back yard. I have not tried it yet and I have a couple questions about how to maintain it. I know nothing about it and obviously I have a lot to learn. Right now it has about 2 inch deep of water (stale and mucky water). How do I remove the existing water? The liner unfortunately has few cracks and previous owner patched them up poorly. I'm hoping to have it replaced sometime next year with more durable liner. For the time being, I want to enjoy it for the remainder of the summer. I will need to buy chemicals to treat water to prevent algae growth and mosquito nesting. I'd like to know if it is possible to add water supply to maintain the water level in pond (something I'd like to do next year). Also, do the chemicals used to treat water harm dogs?

Any relevant information regarding pond maintenance will be greatly appreciated! Thanks.

Rather than chemical treatment, try something biological. Chemicals tend to use chlorine or copper based compounds which can make animals sick. You will want to get a bio-filter eventually anyways, so why not get it now.

Larvicides are available for mosquito control. They arrest mosquito development. There are algae fix products available and pond dye which prevents the amount of light that promotes algae growth.

How large is the pond? Pump? Filter? Water source?

http://www.naturalsolutionsetc.com/garden-pond-algae-control.htm