Baby brine shrimp is a good food for Paros of all sizes. But I am not quite sure what you mean about linking Brine shrimp with Hydra. If you are worried about brine shrimp though you could try Micro worm or Vinegar eels if you can get them.
I am not worried about brine shrimp. But I do only feed young fishes daily with artemia, because in all my aquariums hydra increased after feeding so often brine shrimp. After I have seen the juvenile paro, I feed artemia every day and the hydra are happy too 🙂
I have experienced this co-appearance of small green (!) Hydra spec. with Artemia-feeding too, but only now and then, quite irregularly.
If you don’t know Flubenol as a very efficient and safe remedy against that, I direct you to my message No. 231 in reply to Jacob’s problem (see American/Methods).