Backyard Aquaponics
A place to discuss aquaponics

..
So we are completely convinced that ZINC is seriously toxic to Native Australian.fish..

I am still unwilling to risk such fish in my old system, despite the fact that Koi and Yabbies have prospered in there..

But, having heard of a.similar disaster as I experienced, I again wondered just how one could rehabilitate the media, and especially EC media, which seems to lock the zinc away, and release it just when you add new fish.

Now if it was my body that was affected, there would be a treatment regime that might chelate the metal..

I recall that one issue is measuring the contamination, and the suggestion that the detection threshold of typical kits, was actually above the lethal concentrations for SP.. ie... you would show ZERO and.still be killing fish..

So my obvious question is .. ".. is there a safe technique to chemically remove ZINC from a.system, whilst not providing a new contamination from the chelation method.."

Obviously, water changes would help the process, but repeating myself, this will NOT remove the real problem.. ie. That Zinc which has been absorbed into especially porous media like Expanded Clay and I assume Scotia..
..

Sounds like hydrochloric acid?

http://umexpert.um.edu.my/file/publication/00003241_23472.pdf

As im the other example, as i said in the other thread if you havent read it yet;

although i havent tested since i got the fish (i tested before and had dropped to the lowest test score of 0.6 or below and then did another water change) i have only lost some at the start, i think due to my own "preparation" of the system for more fish, without leaving it long enough for my piss to be totally consumed.

I did add Fulvic acid, i did do more involuntary water changes (leaks and refill) and eventually although im sure there is still zinc in the system, it is happily supporting murray cod and bass fingerlings of about 5cm long.

I still have not come across anything guaranteed.

the cuprisorb that i bought never changed colour, so i dont think it actually absorbed anything even though the site says heavy metals, not just copper.


Bui, another thing i saw on gardening australia (some citrus expert talking of zeolite) is that you can mix zeolite with your potting mix and it uptakes nutrients as you water, then re-releases it.
it got me thinking about your use of zeolite, have you ever thought of removing your bags and placing them into a hydroponic system that is powered purely by the zeolite?

No, you are.just another..
the one I refer.to has not announced.his disaster..


I too saw that presentation ... and have added Zeolite to every dirt bed since.

The suggestion.that the Zeolite would absorb and release, helped to convince me that the beliefs on here about Zeolite, were WRONG..
This prompted me to push ahead with the Biocenosis bags, now understanding that the zeolite would capture and release according to "concentration gradients"
Ie.. the outside of the bag might be saturated in nutrients, and as the inside depletes it's nutrients via anoxic-bacteria, the adjacent saturated zeolite releases nutrients.. creating a kinda-nitrogen-pump ....

maybe there are plants that are good at absorbing the zinc? looks like duck weed takes on zinc but whether it's enough to make a difference I have no idea.

http://ssjournals.com/index.php/ijbr/article/view/683

thanks sig. i looked for plants that eat zinc but couldnt find anything.

bui, good point about the gradiant, since it cant absorb a lower amount, the nitrates in the water should always be higher, so shouldnt re-emit into the water.

Not sure that HCl would help in AP, as even IF it worked, your aim would be to treat the clay/media.. This could have significant impact on the clay, and just where would the "recovered metal" end up.. and you could not do it on a working system ... dead fish and bacteria I suspect..

Perhaps, this is the whole problem.. no point converting the metal, if you don't remove it..
My suspicion is that you need a method of unlocking the metal from the media, and then do a total water change

Wonder if it is possible to electroplate metals from solution.. kinda like a UV steraliser .. ie .. InLine 24/7
nope... gotta be a dumb thought..
.
PS.. not concerned for myself, but my troubled friend can't afford to ditch hundreds of Bucks worth of clay media.
Plus, we can be certain that others will also find out the hard way, that Zinc is lethal.to fish, and rain water from the shed is BAD.NEWS..
..

You wouldn't do it with fish/plants... you would have to isolate whatever growbed you wanted to "clean"; or put the media into a plastic trashcan or something to soak?

If it's hydroton-type material, I don't think the acid would have any affect... it didn't fizz/bubble when I put it in muriatic acid.

I don't know, it's how they say they reclaim zinc and other metals from plating waste water. I would think that you would then treat the zinc solution with some base and precipitate the zinc out for disposal; so you could dump the water safely and have tiny amount of waste to dispose of?

I have already been through this with Yav
http://www.sciencepub.net/report/report ... rt0105.pdf

Although this relates to cadmium and tilapia just read in zinc and whatever fish your friend has. A slight caution ensure water added to the system has had the chlorine offgassed.

http://www.supremefulvic.com/documents/ ... c_acid.php



as i said in another thread, im not 100% convinced fulvic solved my problem, i am constantly refilling from leaks - not so much anymore - however after adding roughly 20 teaspoons of fulvic over 3-4 applications to about 5-6kl of water, i now have bass and murray cod babies that are alive and well and showing no signs of dying.

hmmm, if Fulvic acid makes the Zinc *more* absorbable and bio-available, how does that help? Surely the idea is to remove it and make it UNavailable?

i take it as chelation, which makes it "safe" as far as im aware.

if it does chelate it, it should then be absorbed by the plants.


i take this part as the most important.




of coarse, that site isnt scientific, it almost looks like it could be a sales propaganda site.

Now that is a great find.. and I have an inactive duckweed bed in the system.
and the duckweed .. (elsewhere)
I did have the duckweed in the system earlier (pre disaster) but removed it because it was chewing nutrients.. and I really had no practical use for the growth..

WHY did we not find this long ago..

Only DOWN side, is that it will reduce nutrients for your real plants.. not an issue for me

It is interesting to think back..
I had the duckweed in the circuit, for a long time.. and I would occasionally use the roof water.. and I had no deaths.. but it annoyed me that the bloody duckweed would escape to the FT's...
I suspect that MY fish slaughter, started after I removed the DuckWeed, and converted the bed to A DWC..
So it is probable that removing the duckweed, caused the zinc to build up in the system, and then kill all the fish..

THANKS Signore.. That find might save a lot of folk from AP grief..

I suspect that in time the zinc will leach back out of the expensive clay/media..
The challenge will be to control the DuckWeed, which I nicknamed PITA WEED, Because it is such a Pain in the arse...
Filtering all return water should fix the nuisance value of the weed..

My bed will be reactivated later today..
..

your media guard isnt good enough if you are getting DWeed back in your FTs.

what levels are your zinc Bui?

seems crazy to me that its coming from buildup from Gal. roof, all my roofs are Gal., they dont cause a problem, atleast not for me, my problem was from Gal. tanks.

I would think Sydney rain is quite acid due to all the air pollution, which will dissolve Zinc from the roof at a bit faster rate than clean rain would. Whether or not it's enough to be a problem is hard to say. Perhaps more of a problem is that polluted air will attack metals like Zinc even when it is only slightly damp, and the Zinc-rich corrosion will wash off each time it rains.