Both Linckia and sand sifter stars (Archaster) have very poor long term survival records in small tanks (under 100g). Their needs in terms of food are opposite. Sand sifter stars need vast expanses of open sand area...Linckia need lots of LR. Both are unlikely to take to spot feeding. Their needs in terms of tank parameters are critical - mature tank, pristine parameters, specific gravity 1.025-1.026.
Both will tend to die of starvation in 12-18 months, and you should NOT claim success with them until you have had them that long. The will show no signs of problems until their arms start falling off, which most people blame on predation. But it is due in most cases to starvation.
All stars are very delicate anda re some of the most difficult animals we keep. I never recommend sand sifter stars, ever, and Linckia only to established larger systems (specifically with at least 100lbs in the case of an orange Linckia).
Linckia DO NOT eat "algae" and detritus and so should never be added as a clean up crew. They are very delicate, and have special requirements. Sand sifter stars are the opposite of what you want in a sand bed, they are very detrimental to have, IMO.