Hey Jase
I tried that estuarine Chaeto and it's bad. Tried) many things (lighting especially) but it goes rotten.
So I found
http://www.oceanarium.com.au/viewcat.toy?cid=507115
They are situated up near Moore River about 2 hour drive north but deliver to Perth NOR and SOR plus Australia wide. Delivery is FAST and inexpensive. These folks know their stuff. Check it out. They sell a range of live reef and developers stuff (live Mysid for one).
The Caulerpa they sell doesn't go sexual and doesn't require reverse cycle lighting. It's called Paddle Caulerpa and not one of the ones we see anywhere. They have the scientific name on the site. I bought a pack of 500 gram and it is amazing stuff for my fuge. When I trim off excess, I put it in the display and my Foxface Rabbitfish eats it like it's candy. I don't think I want to actually grow it in the DT just in case it grows everywhere, not that I'd mind if the tank wasn't so tall - I need a stepladder to work in it. I have enough work to do ATM and getting old! But, if I had a smaller more accessible aquarium, I'd give it a shot for sure. Anyway, they do have minimum order price. I bought enough to share if you feel like popping up to my place I'll give you some. Being new here, not sure if you can PM me. But feel free to reply here. PM if you can (let me know if you can't and I'll fix my settings). I'll send you my contact details.
Hope this helps you.
PS I just went to the site and it's called
Scientific name: Caulerpa brachypus
Cheers