A "food squirt" is essentially a mini turkey baster. I pop off the elbow at the end of the siphon and suck the air out with the baster. You have to do it more than a dozen times to get all the air out.
The chance of caulerpa going asexual in my tank is unsettling, so i use all non-caulerpa macroalgaes. I keep dictyota, sargassum, halymenia, and ochtodes macroalgae, with the latter being the dominant algae. The sandbeds are as deep as the unit will allow, about three inches. They are filled w/ pods, mysid shrimp, and excessively reproducing strombus snails. Banggai babies go in the mostly cleared out smaller aquafuge. HTH