Water water everywhere

So in upgrading the waterfall outback to a full on water garden and annual koi habitat this year I am thinking that this model of fountain is perhaps the best option for me if I decide to add individual fountain heads, but I am not sure thats the way to go yet..

It's a Home Depot find.. So minus the 10% military discount makes it reasonable for the 3 fountainhead so need plus 2 backup.. I think it should work. But the other option is just a straight out swap for what I have now except its a uv decontaminant as well instead of a plain water push style. 

I'm kind of leaning towards putting in the uv pump and simply leaving the koi in the lower pond, and making the upper basin less of only thing than the water alone, the middle basin a water flowering garden, and the bottom the koi pond with some plants but not many. If I do that then possibly an aerator like this for the middle basin? 

I think that might be the best option.. Any thoughts from the populous? Let me know what you think as far as comparable prices and options.. Hoping that when the girls said 'lets put koi in there' I don't kill all the little fishies (or great giant fishies that they anticipate. I'm thinking more a few comets that we can feed to gargantuan size over a few years, like poor Gertie may he rest in piece. Yes he. I see a Gertie Jr. in my future lol) :)