I finally got up to the local koi/pond store this week and got a couple water lettuce, hyacinth, and duckweed (as a hitch-hiker). I gave both turts two small shoots of water lettuce, and a good spoonful of duckweed each. For once, Ralph didn't destroy the lettuce! Hurray! Frankie on the other hand, has eaten every last bit of lettuce, and has started on the duckweed. She goes after the roots of the plant first, so it has no hope of survival
If Ralph continues to ignore the lettuce, I bet his nitrate levels will stay low. But Frankie's nitrate levels are always higher, no matter how many partial water changes I do. I figured at least some of the duckweed will escape her vigilance, but I'm wondering if it'll make much of a difference in her nitrate levels.

