but I can imagine it'd foul the water really quickly.
I thought like this at the beginning. But I learned from marine breeders who are professionals in breeding marine shrimps (easy and difficult species). There are some experiments with marine hermit crabs, difficult marine fishes and sea horses. They have got experience of over 30 years and I believe them.
And with my project I had to read a lot of things about sea water, salt, aquariums, about algae, about brine shimps and stuff. To understand all the backgrounds.
Puttin in powder food, pellets or frozen food is risky, because the water can turn bad very fast! You have to control phosphate, nitrite, nitrate and stuff often. But this is not that easy, because of water changing. In my case I change nearly 50% water every day (depends on dirt). The values are not measurable correctly.
I know a fish experiment in which the fish larvae are always dying. And they have found out, that a little higher value of Po4 (Phosphate) was the reason, caused by frozen krill.
in a big sea water aquarium it is not that easy to keep a good balanced water. In a very small tank, like kuza's jar or my Kreisel tank, the water is very tricky.
Something you could try would maybe be crushed FD krill or bloodworms? Or spirinula powder?
in my opinion:
I know, the hermit crab larvae are something like 'hunters'. They need living food. They catch their food if it 'swimm' near. They can't pick up food like powder food or pellets. Most of the things sink to the floor very fast and the larvae can not reach it. (even the "instant baby brine shrimps")
And I never saw a larvae catch something else than brine shrimp.
Hermit larvae do not eat like brine shrimps (for example). They probably to not filter algae and stuff. But this is not proven.
The marine breeders adviced me to use living phytoplankton (an algae mix) to get an ocean milieu. Because in other breedings project it is usefull. But the algae will never be enough as food.
Zoo plankton like copepods is risky, too. Some of them can grow bigger than the larvae and can threat them. Some can be too small ot too big.
And like brine shrimp you have to seperate them to get them out of the water. Too many zoo plankton can destroy the water.
Yes. There is no "that one way to raise land hermit crabs" but living freshly hatched brine shrimps is THE food in the matter of marine breeding
Please excuse me when my advices sound strange or overbearing or something like that!
I only want to help and share my knowledge.
And I think: why should you expirience and risk the larvae life, if there are good results with freshly hatched brine shrimps? Why should you "reinvent the wheel"?