Backyard Aquaponics
A place to discuss aquaponics

My main rainwater tanks are up the back, beside the double garage.. the roof is flatish ZincAlume, whatever that implies ..

The collected water is what I would used for the AP systems being assembled ... is this a massive no.no...

Is there any treatment that might neutralize any metals thought to be harmfull to fish..
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I would think you should be ok providing the roof and gutters are in good condition. It's not like the water is in constant contact with the roof - it's just run off.

Matt might disagree with that, see: viewtopic.php?f=18&t=12883&p=461950&hilit=rain+water+tested#p461941

BuiDoi, how old is this corrugated roof and what condition is it in?

If it's newish, non flaking factory coated/painted colorbond it should be ok

If it's just straight up silver gal and it's a smallish surface area, and you're really worried about it, you could consider painting it with a water based, potable water safe roofing paint. I've used Tilemaster roofing paint (http://www.tilemaster.com.au/roof_paint.htm) for this purpose and reckon it's probably the most neutral and fish freindly. My father in law managers their paint factory in Sydney so I trust his advice that theres no nasties in it

Perhaps installing a cheap first flush device on the drainage pipe coming from the roof might help also.. as then you'd only be capturing the fresh rainwater with way less chance of roof surface contamination

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Thanks for the thoughts guys.
The roof is about 10by10M.. and about 20yo and so quite stable..
It would just be nice to think that you could just add something like you do to neutralize metals...

I like the idea of the paint, even as a life extender for the roof itself..

Thanks again and sorry to have not come back sooner.. been distracted with ATO demands.. all sweet now..
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An interesting thread and makes you think.. clearly on possibility is that a Zinc-Flush, after rain, could cause the turn-overs, but likewise other thing like sudden temp. Changes..???

The other thought is that whilst there may be a znc spike after rain, you would think that it would build up and eventually, kill everything..

Interesting comment about water testing, revealing near toxic Zn levels.. but what was it over time, I wonder..
Eg.. there was a suggestion of roof water being a constant source of replacement water, and thus one would think that Zn levels would simply go higher and higher..

I would be painting it regardless of age or condition.I have killed a lot of fish with just a new zincalume gutter on a plastic roof greenhouse.

Now that is pretty telling, and the real issue is likely the NEW word...

I saw something about water purification.. a strange claim about Black Mica, and demonstration of how a putrid pond was cleared b4 your eyes..
Seemed to have a background in using Sulphuric acid on certain rocks and creating this Magic Agent, poohooed as quackery.. but the thought is still there.. could something like Sulphuric Acid convert metals to a more harmless Sulphate.. or? ???

Painting may be the best idea, but a massive task ATM....
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You can buy activated Carbon fiters that remove metals including Zinc, which I think would be a much better idea than performing chemistry experiments with Sulphuric Acid in your fish tank!

I have 2 gal tanks which i recently painted, always had trouble keeping trout alive except a few of the toughest ones , my zinc is at 1.8 according to a test i bought, i had already done a 50% water change before testing.

I have gal roofs which feed my water tanks, the water in them tested at 0.0+ (lowest increment is 0.6 and was below that).