Allelopathic inhibition caused by macro algaes isn't really that new of a finding (just, apparently, new to StirCrazy
). Eric B. wrote about it a few months ago in one of the online publications.
Unfortunately most macros have some sort of pitfall. If you go collecting seaweed on the Pacific shores for example, there is one (I forget offhand which one exactly) that when heated in the sun, would release enough toxins to foul up the water in the bucket so bad that anything tagging along for the ride with it gets killed, whether plant based or animal.
Generally speaking just about anything has some sort of pitfall, and you decide for yourself where to draw the line. A refugium usually offers more advantages than disadvantages, so we put in caulerpa anyways.
Putting caulerpa into the main tank, as Steve seems to have done, is not a good idea. (Steve, I'm not picking on you .... It should be pointed out that I have made this mistake myself, and I'm at my wits end trying to remove it from the main display. I think at this point, a rabbitfish is my only option, short of pulling the rocks and scrubbing them and pulling every last bit off by hand .... which is just not going to happen in the near future). The most obvious reason it's not a good idea is that it is a
terribly pervasive weed once it gets a good foothold. The other reason is the potential for allelopathic inhibition. For the longest time I could not figure out why my SPS weren't growing as fast as they should have been, I finally am guessing that I have allelopathic inhibition going on.
I think, that given water changes and running carbon, and keeping caulerpa in check by regular prunings, can keep the risk at a manageable level. Which leads to another reason why caulerpa in a refugium is a good idea: it's way easier to get at then when it's in your main tank. And keeping it in check is kind of needed anyways, because if they sporulate they release everything they've sucked up, back into the water. So keeping the caulerpa at bay, keeps the amount that ever gets release back in, at bay as well.
The only real risk-free plants, in my opinion, are mangroves (and there is debate as to their efficacy, but that's a topic for a different day
), and eelgrass. I guess spaghetti algae is not bad either. I've been wanting to try eelgrass for years but it's availability up here seems to be quite scarce. There is a variety that grows off the BC coast that has a range that goes down to Mexico and the Baja gulf, which seems to me to be almost typical-reef-tank-temperatures maybe .... so I wonder if someone has done any experimenting with those eelgrasses at reef tank temps and seeing if there was any chances of long-term success with that. (Seeing that you can't seem to get the "true" tropical eelgrasses anymore .... nobody has any ... I've given up on looking for some. If someone knows where to find some up here in Canuckada I'd love to hear about it please!!!!
)