Caulerpa Crashed-Observations


Reeferus Horribilus
Premium Member
Well, I guess I earned another reefer merit Caulerpa crashed last night. I was very lucky, I caught it within 10-15 minutes tops. Water is crystal clear this morning, fish are looking better as well as the inverts, corals, Tunicates and sponges. Interesting that the worst affected was the sponges and my Kole tang.

What I did:
Like I said we caught it within 15 minutes tops, but the display tank was already milky looking, fish were very stressed, all polyps were tightly contracted, sponge looked deflated. I immediately took the fuge off-line. Then I set the wavemaker to rough seas program for aeration. I did a 5g. water change and started RO/DI unit (Happily my unit makes 4g./hr.) I put fresh carbon in power filter and got that running. Made another 5 g. SW, put 2 150W heaters and big airstone in the bucket, got it up to 80 degrees in 2 hours. Then did same with a 3rd. 5g. Long night!

This is the main reason for my post, to add what I can to our scanty knowledge base on this subject. Especially since much of it is at odds with what I've read here.
1. You can keep Caulerpa from crashing by dosing Iron...Nope, I dose.
2. You can avoid crash with extended lighting schedule...Nope, I have 18 hour photo period on my fuge.
3. Regular harvesting will avoid crashing...Nope, I just harvested less than a month ago, fuge was barely 1/2 full.
4. Racemosa is most prone to crashing...Not this time. I have Racemosa, Prolifera, and Mexicana in my fuge. The mexicana is what crashed, some prolifera, didn't see any bad Racemosa.
5. You have time to see it turning....Definitely not. I spend a lot of time looking at my fuge. I saw a few white pieces in the morning (which I removed) crash happened at 5:30PM.

My hope is to tease what I can learn out of this, so any observations, questions, or experiences would be much appreciated. Thanks.
My hope is to tease what I can learn out of this, so any observations, questions, or experiences would be much appreciated.

Maybe switching to Chaetomorpha is in order.:)

FWIW, I recently had a similar experience. One of my refugia has been dominated by thge standard looking Caulerpa racemosa for a few years. It has never sporulated.

After I lost some fish in my main tank last summer, a new type of caulerpa began to appear from a rock. It has periodically sporulated over the past few months. I keep it trimmed back, so the events are harmless, maybe even good. Nevertheless, it sporulated and the C. racemosa never has in the same tank.

This caulerpa looks like that in this thread:

that some identified as Caulerpa racemosa, but it grows side by side with the usual C. racemosa with the grapes, and it stays looking like that.
Maybe switching to Chaetomorpha is in order.
That is a real temptation at this point. I removed all the macros from the fuge. Cleaned up as best I could, then re-seeded fuge with the best looking and youngest cuts of all three again, but mostly Racemosa. I am watching your posts with interest re: Chaetomorpha because so far your experiments have been so completely opposite of my experience. I had it in the fuge by itself for 2 months and it never grew and my PO4 problem never went down. Matter of fact that same bunch is still in the fuge. When it warms up a bit I think I'll order some from somewhere else and try again. I jst hate to abandon the Caulerpa after the remarkable improvments it made to my tank prior to this. If we could just figure out the trigger for sporulation.
Randy, I think that what is in the picture you referred to is Caulerpa racemora var. peltata.
Right on SPC, C peltata.

Also, I have to take exception to the "can't see it crashing", point #5 statement. There is about a 24hour period where the internal "juice" of the Caulerpa is re-organising, IF you are watching really closely, the leaves/stems get sort of yellowish/clear as the green goes into very thin dark strands. Just get it out before the outer membrane finally ruptures and the Caulerpa falls apart releasing all that goo into the water. The consistency changes well (12 hours) after the color, so there is time. Learned the first time what's up, never got caught again.
I have to take exception to the "can't see it crashing
Why take exception? It quite simply didn't this time. It would have had to happen within a 7 hour period. Not saying that what you are saying isn't true, or that it might be true most of the time. I had carefully examined it 7 hours prior this time.


What I was hoping to get a discussion going on is what is the trigger(s) to sporulation? From the things I've read on anecdotal evidence I would say there are numerous, it would be good to identify what they are. Also, re: timeframe, could it be different species to species? Does C.mexicana go from white to goo faster than say C. prolifera or C. racemosa? Would seem reasonable since its mass & size is considerably less.

Also, I had some of that red algae that looks like cotton candy starting up that was really taking off, could it have been out-competing the mexicana for some nutrient?

Question on Chaetomorpha, does it need to float around to grow? Seems like most of what I have read recently has talked about it free floating, I've always had mine pinned down. Could that be why mine has not grown?
Where have you seen or read that dosing iron keeps sporulation from ocurring in Caulerpa spp. Wizardgus?
I'll try to dig up the threads later and post them here. Most of the ones I've read have been laden with qualifiers such as may, might, there is some indication. But, there have been a few. I haven't tried the new search feature here, so will have to see.

In re-reading my original post I should point out that I don't mean to refute that those measures may enhance the survivability of Caulerpa...only that there must be other factors as well. Also, the caulerpa had only been in my fuge 9 weeks, so age wasn't a consideration.

I had posted a question about a month ago re: harvest amounts and timing. Replys were nearly unanimous that wait until fuge is full, then take half. So, since mine wasn't near that, I'm wondering could it be that since the Racemosa is more massive, and tended to grow more densely, could density of growth still been the trigger in my case?
Where have you seen or read that dosing iron keeps sporulation from ocurring in Caulerpa spp.

I suspect that I'm the source of that, whether it ends up being true for some macroalgae some of the time, some macroalgae all of the time, all macroalgae some of the time, no macroalgae any of the time,some, all, none.......

Anyway, it was the result of a poll that I ran here and then put into one of my iron articles. One of the obvious problems is that it lumps all Caulerpa species together as one,a nd yoet many of us see different results for different species.

Here's the first article that has the poll:

a second article on the effects of iron on tank organsims other than macroalgae:
Question on Chaetomorpha, does it need to float around to grow? Seems like most of what I have read recently has talked about it free floating, I've always had mine pinned down. Could that be why mine has not grown?

Mine has always been just a ball that sits in the middle of the refugium, but when it gets big, it hits the sides and bottom and is effectively held that way. It certainly doesn't move around because therer is almost no flow in it. I don't think it likely that holding it down is an issue.

How do you light it?

You might have a different species that I do. There are several, and I've not figured out exactly what one I have, or even how to tell.
Where did you get it?
I got it from someone who had it posted in the For Sale Forum. So, I don't know the species really. My fuge is a 20gT with a (totally useless ;} ) 7" DSB. I have it lighted with 2X55W PC, 10,000K, one bulb is a Hamilton (very bright) the other is a Coral Life.

So, what would be more interesting, to me, is where did you get yours? :D

Also, I read that your experiments were indicating that Chaetomorpha may actually exceed Caulerpa in NO3 & PO4 export? How about the heavies? I think that is what keeps me intrigued on Caulerpa, the chance that it might be a limiting factor relative to OTS.
How about the heavies? I think that is what keeps me intrigued on Caulerpa, the chance that it might be a limiting factor relative to OTS.

I don't know about that comparison.

So, what would be more interesting, to me, is where did you get yours?

Initially from Inland Aquatics.
I don't know about that comparison.
Not sure what you mean here. Is it that my remarks on OTS is another case of me adding 2+2 and getting 5? Or has Chaetomorpha not been demonstrated to export heavy metals? Thanks :D
hey Randy, i have lots of prolifera, halimeda, grape and teacup i can share with you if you want to diversify. i use real seawater and keep my fuge on 24 hours and let my fuge sleep once or twice a month. i have never had a crash and the culerpa is thriving. let me know if any of these species appeal to you.
Thanks for the offer, noni, but I think I'm set for now.:)


I don't know about that comparison.
Not sure what you mean here.

I meant that I don't have any idea how Caulerpa and Chaetomorpha compare to each other as metal export mechanisms.
Thanks for all the info and insights. I guess I'll keep both for awhile. If I had any doubts about the effects of Macros in refugium they have been pretty well removed these past few least as regards nuisance algae in the display. Man, has my glass been green each afternoon!

I think that Macro algae, trace elements and OTS are some of the most interesting areas of inquiry in the hobby right now, so I'll continue to read all I can. Problem I see is how do you account for all the variables? Which brings me right back to my thoughts on the green glass...lack of macros? Or increase in nutrients? Arggghh! I need a beer. Later.
WG, don't want to start any arguements, but I must point out that there are different degrees of observation. I have lived with Caulerpa for over 10 years and have had about every species available on the market. They all crash in a similar manner and it begins about 24hrs before total breakdown.

You may have missed the funny "off" colored like dull green stage and finally only saw the "clear leaf" stage, in which case 7 hours is about exactly the right amount of time to the "fall apart" stage.

Other than that, I totally agree with your experiences. Peace.

ps, Halimeda also goes sexual, and you also get one night to get it out of the tank too. And, surprise, surprise, Halimeda and Caulerpa are from the same family, so it makes more sense to me that they both go "sexual" like that, even though they look totally different.
WG, don't want to start any arguements
No problem, and I know where you're coming from on that. So I want to add, partly for ego and partly so if you can think of something else, that I'm certain of my observation skills. The morning in question included using my plastic planter probe to look through the Caulerpa specifically for signs of sporulation.

You may have missed the funny "off" colored like dull green stage
I have to concede this point. And this could be a continuing problem for me as my color acuity is not all that it could be.:( May have to enlist the help of my interior decorator.(wife) Also, this is the first I've heard of that, been watching for white stage. So, that is good additional info.

Now, one more observation I'd like imput on. It has now been 1 week post event. I had pulled all Caulerpa out of fuge, then selected a few of the youngest and greenest pieces to re-seed. Most of it is growing nicely. But here and there each day a small piece turns white and dissolves. WTH? The C.mexicana does a full feather in one shot like before. The C prolifera seems to start at the tip and recede back down. The C. racemosa it will be just one cluster. So far it is maybe a 1 inch piece each day, not always in the same spot. Since it isn't causing any trouble I am letting it go to try and see what the progression is. Any ideas why it would continue?

Am I dong something so blatantly stupid that no one wants to comment? Thanks for any help or info.
I've been working with various Caulerpa spp. for about 4 years now in my 55 gallon tank. The first set-up I had used C. racemosa var. peltata and it never showed any sign of impending sporulation until the tank crashed on my honeymoon due to a clogged overflow :rolleyes:

Currently my tank has some Caulerpa spp. that I have been too lazy to identify ;) I also have some Sargassum that is growing like a weed. The red against the backdrop of the green macroalgae is quite beautiful, and I plan to move it to the display tank when I set it up (see note below.)

My aquarium is 55 gallon with a 40 gallon sump, 2-4" sand bed in main tank (slowly building up to 5") and an 8" DSB in the sump. I have a medium sized ATS type device that nearly covers the 40 gallon sump and is powered by two of the large LOA lights. No skimmer, because the POS used Berlin skimmer a friend gave me didn't do much, was tempermental, and eventually failed. I'm planning on adding a MyReef skimmer. My main tank is actually the refugium, with no predators, fish, or coral in it. I'm saving for a large tank when I buy a house in the next year or two and this will be mounted above the main tank. There is a fairly thick (1mm) detritus layer on the sand bed that has a mind boggling array of little mysids, copepods, amphipods, and little nearly invisible worms.

I leave town for a few days at a time, twice a week. At first, I was not dosing iron. One or two strains of Caulerpa ended up turning completely clear and disintegrating. Oddly, my tank never got very cloudy. This may be because I have a ton of little feather dusters of at least 4 different types and a pretty deep sandbed. Oh, and I have a 400W radium on an HQI ballast about 6 inches from the water in the 55 gallon. This is a 55 gallon tall, so it is only 3' wide, and about 18" deep. The macroalgae seems to grow as well in the sand bed as it does on the rocks.

Since dosing iron, some of the macros which looked about ready to sporulate have regained their color and continue to grow quite well. This has not inhibited growth in the ATS, and I also have a small amount of nuisance algae on the rocks. This is very limited, and even running the useless Berlin skimmer prevented this. The eventual addition (right after the skimmer) of a RO/DI unit will probably ensure that this goes away.

What I see now is that occasionally 6 or 7" strands of all of the Caulerpa spp. in the aquarium will be clear. Again, the tank doesn't get cloudy. It seems to be a semi-continuous process. One part of the colony will go clear, while a side shoot off of the same "stalk" will be dark green and growing well. There hasn't been a large collapse of anything since I started dosing iron. I'm guessing that nitrogen is not limited in my tank, so there is plenty of fertilizer that way. The tank is well aerated with a fast turnover (2 mag7) to the sump and a Mag18 that runs the ATS. I'm pretty happy with the way it is running right now, but wanted to add some anecdotal info regarding partial sporulation events and the effect of iron and possibly other nutrients.


P.S. I'm planning on adding 1 300g rubbermaid "sump" to get more live sand and rock and probably some corals and fish ready for the eventual display tank. This will be in about 5 months. At that point I was planning on putting a tang in the 55gallon to eat as much of the Caulerpa as possible, then moving it to the 300g to get big. I was planning to switch primarily to Chaetomorpha in the 55g, though I'm sure that the Caulerpa would come back as well since the tang couldn't get all of the shoots that are in the sand and between rocks.