Using electrical current thru submerged structure to form reef base

[Benjamin Slade]

From a posting on Slashdot.org:

> Applying a low voltage electrical current (completely safe for swimmers
> and marine life) to a submerged conductive structure causes dissolved
> mineral crystals in seawater to preciptate and adhere to that structure.
> Surviving coral fragments are mechanically attached, and end up doing
> very well indeed.


Here's the original posting:

http://science.slashdot.org/article.pl?sid=04/08/23/1133213&tid=191&tid=134&tid=14

> A Solution for Corals Reefs in Peril
> Posted by Hemos on Monday August 23, @09:01AM
> from the trying-to-correct-our-own-mistakes dept.
>
> Alien54 writes "At the recent Coral Reef Symposium in Bali, Indonesia,
> scientists concluded that most of the world’s ocean reefs have been
> killed or severely damaged with the remainder in certain jeopardy.
> Disastrous reverses in reef health threaten marine biodiversity,
> tourism, fisheries and shore protection worldwide.
>
> Reefs die for many reasons: rising water temperatures, sewage flows,
> eutrophication, disease, and negligence. A reef ecosystem that took
> hundreds of years to grow can be destroyed in a single afternoon by
> dredging, dynamite or cyanide fishing.
>
> But there is a solution. In pilot installations in Mexico, Panama,
> Indonesia, Maldives, Thailand, and Papua New Guinea, artificial reefs
> have been built where corals grow rapidly even in stressed environments.
> Applying a low voltage electrical current (completely safe for swimmers
> and marine life) to a submerged conductive structure causes dissolved
> mineral crystals in seawater to preciptate and adhere to that structure.
> Surviving coral fragments are mechanically attached, and end up doing
> very well indeed.
>
> During the 1998 warming, fewer than 5% of the natural reef corals
> survived. But on the artificial reefs, 80% of corals not only survived,
> they flourished. Corals from these reefs are now recolonizing the
> surrounding natural habitats."

Has anybody tried this in a reef tank?

Ben in DC

(append 030516 to the subj to bypass spam filters)
"It's the mark of an educated mind to be moved by statistics"
Oscar Wilde

[Tidepool Geek]

"Benjamin Slade" > wrote in message
news:BwoWc.34$6b.15@trnddc01...
> From a posting on Slashdot.org:
>
>> Applying a low voltage electrical current (completely safe for swimmers
>> and marine life) to a submerged conductive structure causes dissolved
>> mineral crystals in seawater to preciptate and adhere to that structure.

Hi Ben,

The idea of building underwater structures through electro deposition has
been around for quite a while; I remember reading about it in either
"Popular Something" or "Mother Earth News" in the early 70's.

I think that there are potential problems with using this technique for a
home aquarium. Since home systems are, almost without exception, closed
systems you've got to be very concerned with contamination. Assuming that
you've got access to a body of sal****er to 'grow' your structure, there are
at least three sources of contamination to worry about:
1. The armature - It's got to be electrically conductive so you'd probably
use metal (although I suppose that carbon fiber is theoretically possible).
Obviously, anything containing copper is out; I suspect that zinc would also
be very bad so galvanized wire is also out, plain steel has been a suspected
cause of diatom blooms in aquaria; Stainless steel could also be a problem
because of a phenomenon called "crevice corrosion" that happens to SS under
oxygen poor conditions and would also allow iron into the water; that leaves
titanium which would almost certainly work but might be prohibitively
expensive and is also not the easiest material to work with.
2a. The precipitated material - If it comes out of solution from salt water
there's a good chance that it will go back into solution as well. My guess
is that the primary material would be CaCO3; if that slowly re-dissolves
it's probably no big deal since most reef aquariums need a good supply of
this to keep 'stonies' happy. OTOH: Who's to say what other materials might
be incorporated into the structure. Many other chemicals can cause serious
repercussions if they get even a little bit out of balance. For example, it
doesn't take much phosphate to cause heavy plankton blooms.
2b. The precipitated material - Unless you have the good fortune to live in
an area with pristine waters, you've got to be concerned with the chance of
introducing industrial, municipal, or non-point pollutants into your tank.

About squid: Here again you run into problems due to the closed nature of
home systems. The main thing is 'inking'. If your squid becomes alarmed
he'll ink and, unless you have a large volume AND a very efficient skimmer
you are at risk of poisoning some of your other animals. I have no idea what
a safe 'gallons/squid' ratio might be.

Another potential problem is salinity. Many (but not all) squid require full
strength seawater to survive some reefers recommend keeping salinity
slightly low for reasons that escape me at present. If you aren't sure of
your squids requirements you could be sentencing it to a slow death.

Finally, squid are predators and pretty effective ones at that. I would be
concerned that putting a squid into a community tank might result in your
having a community of one squid.

It's a shame because ceph's have to be just about the most interesting group
of animals in the ocean.


Doubly yours,

TG