Grape caulerpa... killing corals?

[mjmccusker]

I have a 10 gallon mixed reef with a 5 gallon refugium... I had lots of trouble growing chaeto in the refugium and had algae problems in the main tank, so added some grape caulerpa to the refugium instead, and put the light on 24/7 (so not too worried about it going sexual). This has been great for my nutrient uptake and nuisance algae which have really diminished almost completely, even if I overfeed.

However, I think the grape caulerpa is releasing toxins that are harmful to my corals (I have heard it does that). My cap montiporas are slowly dying, however the wierd thing is my montipora digitatas, green slimer, and acro sps are all fine, in fact doing well. My LPS are loving it, but my zoas are not opening up as much as they should. Any ideas? I am thinking right now I might just keep the caulerpa and replace the cap monti's with some other sps or lps. The thing is I thought cap monti's were pretty hardy. Any help/experience would be greatly appreciated.

One other thing I have done is add some carbon to the refugium however that doesn't seem to be stopping the process of the montis dying off.

 

[roshi719]

Are youharvesting algae out of the refugium at all? If so how much? also is the carbon being run actively or passively, ie. in a reactor or not?

 

[Wy Renegade]

Not that I would ever do it again, but I had not trouble growing monti caps amonst Grape caulerpa; I would guess that your problem lies elsewhere.

 

[Ike]

I'd be more concerned about stripping too many nutrients from the water than toxins from the caulerpa. For me it's always a wacky balancing act to keep Zoanthids and Montiporas looking good while keeping nutrients low for Acropora. For some reason more frequent water changes seem to help as well, so it could be some particular element (that we don't test) for the montis as well.

 

[mjmccusker]

I guess I run the carbon passively, it is in the refugium in the water flow, plus I have another overflow pump which passes through carbon... and I haven't harvested any of the caulerpa yet. I get the feeling the nutrients are very low and that could have something to do with it? I do a 10% water change every week...

 

[Ike]

Any fish in the tank? What do you feed?

 

[mjmccusker]

I have a yellow watchman and a false perc in the tank... I feed rods, flake, and dried mysis...

 

[Murfman]

What are your alk levels?

 

[mjmccusker]

What are your alk levels?

Here are my parameters:

Alk 9
Ca 480
Mg 1570 (high I know... could this and high Ca be a problem?)
SG 1.026
Temp 78
Nitrate<0
Phosphate<0

 

[Paul_N]

I always run my mag around 1500-1600. 480 is not too high for calcium and where I keep mine at.

If there is something in the water, running carbon passively is the least effective way to remove it.

 

[RadReef]

The only way that I was able to get rid of my grape caulerpa was by adding a green mithrax crab. I battled the stuff for almost a year, but the plant only needs to have hair roots down in the rockwork to regrow and it does! After about two weeks after adding the crab the algae was gone and never returned.