Well i think we should ask about your total system volume of water, and how deep the pool / pond area will be, PDF's cant swim. Even though they will not be doing laps in the pond area i always like to think of filtration as a part of the old addage " you are what you eat " but in this case drink, tis why we gut load crickets

. imho all tanks that have a water feature should have M.C.B filtration and this does not have to be expensive at all, you can DIY your own for maybe 20$ and run all 3 types off the pump you already have, it just takes some planing to get it right. Containers can be found at any dollar store ( cereal containers ) and a couple lengths of tubing. pick up some activated carbon and some filter floss and your in business. If you like i can find some good links or explain the DIY aspect further if interested.