Caulerpa going sexual

[Ruu]

I keep seeing people bashing good old caulerpa, so I thought I would chuck my experiences into the arena. I've been keeping several Caulerpas for many a moon now, and i think that they are pretty good as long as you stay on top of the pruning - they have certainly kept my tank manageable with virtually no water changes (one every month or three). Personally, I keep chaeto as well, but it doesn't seem to grow anywhere near as fast as any of my caulerpas, and I can't see how it could keep up in terms of nutrient export. My thoughts...

A sexual event is not necessarily all that bad for a tank, as long as the tank is relatively large - I must have had at least a dozen in the last year or so with no ill effects (aside from cloudy water for a couple of hours, which the filter feeders probably quite like).

I think one trick is to keep separate "colonies" - one thing I have noticed is that when things go sexual, every connected piece of the algae goes at the same time, but separated sections of the same species will not go at the same time.

Sexual events *always* seem to occur within 30 minutes of my lights coming on, so I think that there is some merit in the claim that a 24 hour lighting cycle might prevent bad events.

A well pruned bed of any Caulerpa that I have kept will not go sexual - I agree with the idea that it goes sexual in response to some form of nutrient starvation. Once you have kept it or a few months, you have a good idea of when your system has "too much". All of my sexual incidents have been associated with lazyness, or wanting to wait until the weekend to perform a trim, even though I knew there was risk.

The grape-type caulerpas that I have kept have warning signs that appear several days before an incident, the razor caulerpa I have kept is much more unpredictable, and has popped on me with no warning signs at least twice.

Just about any Caulerpa is a noxious weed in the main tank. Use in a refugium only, and if you see any trace of it, spend the time removing it immediately, or you will regret it later (unless you like trimming rocks for hours with a pair of tweeers).

Anyway, just my 2c.

Dave

[Fredfish]

one thing I have noticed is that when things go sexual, every connected piece of the algae goes at the same time

If I understand correctly thats because it is all one cell.

I agree with the idea that it goes sexual in response to some form of nutrient starvation.

Try this as an experiment. Get yourself a nitrate test kit. Wait for the nitrates to hit close to zero (I can read down to .2ppm on my seatest). Watch for signs of your caulerpa getting ready to go sexual. Now give your tank a shot of nitrate (f2 formula if you are growing your own algae) to bring levels up to around 2ppm. Don't prune your caulerpa and watch what happens.

I did this with my tank several times. I have a bladed caulerpa that starts to get blades that look semi transparent like it is about to go sexual when nitrates get low. A dose of nitrate and it greens right up. As the nitrates drop below .2ppm the algae starts to get that transparent look again.

Fred.

[Ruu]

I have several nitrate test kits, and I haven't recorded any measurable nitrates in my tank for over a year now (not even on the sensitive end of the Sailfert kit). It has, to be honest, been something of a mystery why the macro grows so well (I pulled about a pound of various macros last night) - I am assuming at this point that they are simply utilising nutrients as they become available, but with a certain amount of growth in the tank it becomes too limited and goes sexual. I would play around with fertilizers, but since the system is doing so damned well at the moment I am loathed to start playing with it in case it affects the equilibrium - when I get the new tank set up in a couple of months (240 gallon monster), I will have a go. Just to give you some kind of idea, below is my 20G refugium a few months ago - it is a little better managed now, but that is the level of growth I get in a couple of weeks or so even after some savage pruning.

Dave

[Mike4284m]

What do you use for light? That refugium looks great.

[Ruu]

Not much really - it is a 1x65W Coralife fixture with a 6700K bulb (which needs replacing soon come to think of it).

Dave

[Fredfish]

Looks like you are getting good growth in your refugium.

I think you are right about the nutrients being sucked up immediately as they become available. I used to puzzle over that in a previous tank.

My current setup is so lightly stocked that I have to dose to keep the macro going: 3 seahorses in 80 gallons total system volume.

Fred

[Plantbrain]

Dave one key element, pruning the weed.

That means the uptake removal will be the same. Biomass is = most of the time,and the uptake will be stable as well.

If you let the weed double or triple in biomass, then you would need to feed the monster 2-3x as much also.

Folks tend to let the weeds grow and not trim them, then they eat themselves out of house and home.

I've kept 10 species of Caulpera and only when I did the lower/absent NO3's did I get them to respond sexually and this was the typical 12 hour light cycle.

Regards,
Tom Barr