Good to hear they are on frozen and it should be the main food you feed. I don’t ever feed live to my seahorses. They may find pods in the rock but that’s it. Also rinse the frozen mysis if your not already doing it. It will keep your water quality better. I also feed two times a day, one in the miring and once at night.
It’s hard having people take care of them while away for me at least, I’ve done it but by time I come home the tank looks terrible.