want to add some macro algae to tank

Anthos312 here is some info on that crab Turtle weed crab (Caphyra rotundifrons) still cant find what they eat im guessing the grass since its green like the grass.

 

kelp is a type of tall brown coldwater algae,

calcified algae are generally easy to keep if you keep your alk and calcium in check. They have coral like care requirements, and that make them familiar for some. Halymenia like said above does look good, I think caulerpa is easier to keep and care for than what you hear about. It is likely to grow fast and spread throughout the aquarium, but that might be the point in a planted tank. Lots of other species out there, the sky is the limit really. What kind of light are you running?

 

150W MH 14k Phoenix bulb, looking to pickup some supplemental lighting to make the colors pop

 

The little crabs eat meaty foods. That's how I discovered them in the first place. When I'd feed, I started seeing the grass move, then they'd grab anything that hit the grass.