Starting a macroalgae refugium


So it's difficult to get macroalgae here in NZ as it is illegal to sell but you can swap between people non-commercially.

Now I've gotten hold of someone who has 3 types of macroalgae in his sump. He doesn't know what they are but one is red, one is green caulerpa and the other one is some other green one (he knows it is not chaeto). He's gonna give me a small handful of each type.

I'm gonna get a 23W CFL bulb from the local hardware store and light the sump 12hrs a day (RPL period thing).

Now my tank is cycling. When can I add macroalgae? Do you have any tips for setting up the refugium? I was just gonna chuck it in the middle section where I keep my live rock and put the light on and that's it.


Do I wait till I read nitrates? Or wait till entire cycle is down and parameters are stable?

Hmm wonder if I would need to stop my GFO...?


Active Member
Every since I saw someone's tank "explode" from caulerpa, I've had terrible nightmares about it. Call me a pansy, but I am afraid to use that stuff.

florida joe

Well-Known Member
The issue is Caulerpa can reproduce sexually. In your sump or refuge. You want to make sure you do a heavy cut back regularly. This will help prevent it from spawning and wind up in your DT. It assimilates nutrients so the pruning gets them out of your tank allowing new growth to continue to feed on the excess nutrients

bang guy

+1 on what Joe said. I strongly recommend trimming out at least 1/3 of the older growth every week. Even if it isn't growing trim out a third of it.


Ah yes I hear from about caulerpa going sexual. Some local people told me they use longer lighting periods and they have never had a problem with it going sexual. But I may choose to leave the caulerpa and try the other two first.

Thanks 2quills! But I live in NZ and biosecurity would not let your package in.

Out of curiosity, if it went sexual and you woke up to see white milky stuff all over your tank, what on earth would you do?


By the way I heard bout this cool thing called Xport NO3. Marine depot just posted a video of it on their YouTube channel.

I am considering getting it, it seems incredible that one brick could do 1000 gallons filtration. I only have 100 gallons but I am considering getting it shipped from overseas.