Nope, not too late for Tilapia. Water temps here just hit 70�F, and that was before this cold snap. Thanks for the update on the TH feeder!
Kelly, I think thats a great idea! To add to that suggestion, I would also recommend monitoring the pH of the water going into the pond using that system.
It might not be a drastic enough swing to change anything in the pond, but you'd never know without first checking.