Crocea's ok on sand?

fwiw, I have 3 croceas, and all are on the sandbed of a 24" tall tank. They are very happy there.

Typically yes, they like to be on rocks and up higher though.

 

ok, good to know, if he jumps one more time ill leave him on the sand.

This is where he's at now, i turned the vortech back up but it was just too strong its about half way turned up right now and seems to be ok, but if he jumps again ill just move him to the sand

 

How much lighting do you have and what spectrum bulbs? Croceas tend to do best under shallow water bulbs, like 10000K or even 6500K bulbs. You can get away with a good quality 14000K bulb if it has enough in the shallow spectrum.
Clams will detach when they aren't happy, as you know. And jumping down doesn't necessarily mean it's getting too much lighting, it's just trying to find a better spot. I read a thread where someone said that. "I have a 65w combo power compact over my 55 gallon reef tank and maxima clam. Well obviously the lighting is too strong for him since he jumped off the rock." Talk about being under the wrong impression.