Never heard that before. Is there any science to back that up? I'm not saying your wrong, I would just like to be positive about it before I tell anybody else. :wink:
I guess now you have. :xd:
Basically what happens is that as plant life sucks in nutrients it also sucks in just about everything else including copper and other toxins. Which remain in the plant tissue because they are not utilized by the plant.
And of course those toxins are at a low enough level comparied to nitrogens to not kill the plant.
Environmental engineers are very aware of this effect.
Using dead plant tissue the effect is called biosorbtion with live plants it is bioaccumulation. Or terms something like that. (just an engineer not an environmental scientist
oh
For instance toxins at toxic waste sites like dioxin are sucked out of the ground with fast growing popular trees.
Industrial waste water can be cleaned up with dried seaweed.
Of course, environmentally what you do the the contaminated popular and seaweed is another question. With the seaweed I have seen reports things like cadimum can be removed and the seaweed reused.
I asked Dr. Walter Addy if any more quantative analysis had been done and he stated no. But he did at one time propose using macros to clean the copper out of coolant water used at a nuclear power plant. The plant later decided to go with biosorbtion instead of the live macro algaes.
In a somwhat ironic turn of fate one post on the other board was a WHO study of the effects of copper on corals. Which show the usual dasterdly low levels and high effects of copper.
But way down in the report was actually experiement with live macro algaes and the amount of copper bioaccumulated.
In that experiment, some macros were exposed to various levels of copper up to 250ppm for up to two weeks.
The copper levels in the plants were then measured.
It turns out that the bioaccumulation was linear within the test times and levels and linear to both. The levels had also not reached a platue but were also continueing to increase.
One macro algae started at 50ppm copper and after two weeks exposed to 250ppm copper contained 1030ppm copper.
And of course corals are affects at levels like 50 ppb to the 250ppm would not be a good environment.
But 250ppm according to a Dr. randy holmes-farley article is at or below the at tap copper levels in at least 75% of the major cities in the U.S.
Finally, by harvesting the macros regularily you remove copper from the tank.
And by assuring you are not adding copper you keep the copper out. So limiting water changes helps the copper come down.
Of course what every one does is simply use RO/DI water to prevent the copper from entering the system in the first place.
But in the case here with an old copper treated tank (20 ppm or so?), well rinsed out, cleaned up, a few weeks of good macro growth and harvesting should lower copper to levels safe for corals.
I maintain that you can do the same thing and have excellent coral growth with a refugium full of rapidily macros, regularily harvested, and by not doing water changes.
But that's just my .02
