Coral-Macro Allelopathy...have some questions

[dragonfly1972]

I am looking for anyone who has knowledge of macroalgae allelopathy, particularly coral-macro allelopathy.

I am trying to research a problem in my reef system and I have some questions.
First off...I have a 90 gal mixed reef tank, a 20 gal sump and a 20 gal display refugium.
I am not new to reef tanks...I have had tanks for 18 years (had a 3 year gap without tanks in there somewhere) so I know good/bad parameters and all that jazz.

My problem is that I have something affecting corals in my reef. I initially thought that I was experiencing softy wars (and that may still be part of the problem) but I believe that there is more to it.

I am unable to grow most SPS in my tank. Anything encrusting slowly dies.
It's not a placement issue, not lighting, not flow. I have been fighting this battle over a year now and have tested many variants.

I believe at this point that I may be dealing with Coral-Macro allelopathy.
My display refugium has about 15 different macros in it. All grows great! One macro that I can't keep, Padina...it literally disintegrates over a few days. I have tried it several times. Padina is a non-allelopathic macro from what I have read.

If I run carbon constantly it seems to alleviate the issues...remove carbon and within a few days everything in the flow of my one powerhead starts doing poorly. That powerhead is directly under the return drain from my refugium.
I initially thought that softie wars were happening and since 2 softies were in this flow pattern that is why I was having issues.

To bolster my thoughts, I setup a tank for a friend and for my brother a few years back. They have the same lights, same equipment, feed the same and so on as my tank except they do not have refugiums and I am able to take all of the corals that do not grow for me, put them in their tanks and they flourish and do wonderful! I have taken frags of the same coral from them, put it in my tank again and NO go! Frustrating!

So after all of that blabbering...My question is has anyone had this experience? Have knowledge of these issues? Or know for certain what all macro can cause this?

I'm open to any suggestions or questions.

[Michael Hoaster]

Very interesting question!

Your experiments comparing with those other tanks was a great idea. It does seem to point to your refugium. 15 different species confined to 20 gallons sounds like a scenario conducive to allelopathy.

As another experiment, you could reduce the number of macros to one, so there's no competition for nutrients. If that fixes it, you can point to allelopathy.

Another possibility is that your system is so nutrient poor, that the macros are leaching nutrients back into the bulk water to feed themselves. Corals wouldn't like that either. Seems unlikely given that they are all growing well.

Well, that's all I've got! I hope it helps and good luck!

[dragonfly1972]

At first I thought possible lack of nutrients also. I started dosing phyto on a regular basis...nothing changed.
All of my macro grows extremely good. No lack of growth, no die off.

My plan is to remove some macro but I want to make sure that I remove the macro that causes the most problem.

Or...dreaming here...maybe someone has had this problem and there is a way around it.

[BlueCat1949]

I have never read anything about allelopathy, which is basically chemical warfare, from plants having effects on corals. I suppose it is possible but I think you would have to research scientific journals on something like that.

From my understanding in the FW plant world allelopathy is used to keep competing plants from growing near an established species of plant. I am not sure if macros even use this process against other macros but if they do having 20 species would be quite the cocktail of chemicals.

I would be interested in hearing more about this subject.

[dragonfly1972]

I have researched quite a bit and there are several studies on this.
I would link some on here but my kindle doesn't let me. I will tomorrow from my desk top.
There are macro that do this and obviously some that don't. I will able to find data on several that I have but not all.

[dragonfly1972]

Let's see if this works.
http://www.advancedaquarist.com/blog/the-complicated-chemical-relationships-within-coral-communities-is-astonishing

http://www.pnas.org/content/107/21/9683.full

[BlueCat1949]

This is interesting to read. It does make it look like the plants have to be very near the corals for the Allelopathy to work. Of coarse there is no way to tell which of your macros are doing anything out of the ordinary.

The part where the macros are more attractive to fish for food seems to be the counter balance in the equation.

Thanks for posting the links.

[Subsea]

The reef is a dangerous place. Softies going after hard corals with chemical warfare. Sweeper tentacles from LPS clearing space from everybody. Macro chemical warfare against grazing fish. Now we find out that macro is having chemical warfare against coral.

After 40 years of reef keeping, I have used many different techniques. The one thing that has never changed is my use of activated carbon. This thread further illustrates the benefit of activated carbon in marine aquarium.