Hi Matt
Yup, more plants will help. I live in Mesa so I know how hard it is
for some pond plants to grow in the desert sun.
Lilies will do OK, but seems like you need at least a little shade
from marginal plants for them to survive. I have had good luck with
Hardy Lilies, Umbrella Palms (they are doing great), catails from the
Salt River, and pennywort. If you want Arizona grown plants, try
www.azgardens.com, they are actually located in Tucson. I've never
gotten pond plants from them, but my brother got some nice aquarium
plants a few months back. You can email me if you want.