We ended up using a risotto container for our sun coral because of his shape -- bottles were too narrow -- I think it's just whatever fits.
Then our trigger figured out what we were doing when the plastic container came into the tank and he could steal food as fast as we could pump it.
So finally we got smart and drilled a hole in the top of the container. From there, we inserted the head of a large syringe filled with ro water and brine shrimp bits. Depressed the plunger once the whole setup was in place and waited 10-15 minutes. We ended up learning to shut off the fans so the container was more stable.
Honestly, after a couple of weeks of feeding the coral this way every couple of days, we gradually transitioned to target feeding him after lights out without the container and that has come to work pretty well.
For us I think there were two things: finding a container that fit over the coral without scrapping the sides and using the syringe so that we could insert the food once the container was in place instead of trying to put the food under the side of the container.
We still have a pretty demanding coral but gosh it's pretty!
Good luck!
