Trying to clean algae in sandbed

I've pretty much got control of my rocks with hair algae but need help with my sand! My whole sand bed has grown hair algae all over it and ive tried siphoning but it cant even suck up the algae, i just end up sucking up my own sand bed. i try removing it by hand and still just pick up sand and then the hair algae grows right back within a few a days. I bought some turbo snails and they cleaned the back of my tank and my rocks but i need to know how to clean up my sand bed. Help!

I also have a Kole Tang who eats the junk off rocks. And a lawnmower blennie. But the tang bothers him. If I siphon out sand, can I add new sand without causing a cycle? I've heard something about adding it with a length of PVC pipe. Is there a contraption that can be used to siphon but leave sand?

Thanks!