man looks good! you should throw in a handful of cherry shrimp or something just for fun. there is a guy down here in ft. lauderdale who sells pond plants and koi and he threw some cherries into a lotus pond for fun and now he's got 1000's of them all over the place in there. The only way he even noticed them was a customer asked what the little red critters were climbing on the stems of some of the plants! Here is a pic of his pond where they live:
He has told me the pH is 5.5ish and they still breed very heavily.
Anyway, i thought you might be interested in trying that.