I bought a pond kit at my local homedepot, model #lck535. Will the filter in this kit do the job, it's just a sponge on a pump? The pump/filter shoots water out the top like a foutain, will this be enough. I do plan on putting some fish and plants in the pond. The liner size is 16-12, my depth will be about 24" at the deepest side, and maybe 18" at the lower side. I would like to add a waterfall next year, if this can be done after the pond is up and running? Or does the waterfall have to be planed and installed now?