Backyard Aquaponics
A place to discuss aquaponics

I have a galvanized rain gutter that I'd love to use for a solids filter and additional grow space, but I've read passing comments about zinc here and there, would somebody explain the problem with zinc, whether I'd be able to use the gutter, and whether painting the inside would fix it? I haven't been able to find definite information about it, but at the same time I don't want to kill all of my fish or plants.

Sent from my C811 4G using Tapatalk

zinc is toxic to fish at low levels.

some fish are more hardy than others, if you only ever run gold fish you may just get away with it, other fish, no.

painting probably wont help, i had galvanised tanks and painted them with rubber sealer paint, it did nothing to help.

i then re did one in old fibreglass "flowcoat" and although i havent been able to test it properly yet, that seems like it would work.

short answer is no.

Also, being Galvanised... During the Galvanising process use of acids and other non fish friendly processes are utilised, so the old saying applies... If in doubt, avoid

What about if I used the gutter on a shed, as part of a rain collection system?

Sent from my C811 4G using Tapatalk

If I use the water from the collection in my tank do you think it'll kill em? I'm running goldfish and maybe crays soon.

Sent from my C811 4G using Tapatalk

Some say yes, some say no.

i would say yes, atleast for now with goldfish.

you may want to check the LD50 of zinc to whatever you are planning on having in your tanks.

zinc roofs / gutters will put off roughly 0.15ppm zinc as the water flows over it.

Rain water collection is different, the water only touches the zinc once (still risks, but much less). In a system, the water continues over the coated steel many many times, and the problem compounds.

Just look for the PVC alternative. Or get a proper growbed, it'll work out way better (only so many roots can grow in the space of a gutter, eg, tomatoes will clog quickly).

EDIT: Yav beat me to it.

..
I have been cynical about just how much Zn would be picked up from a roof during a shower..
Problem is you never know the current degree of oxidation.. and how much will come off next time..

Then I read a paper on safe levels of Zn with various AC fish and some of the LC50 levels were half what any standard Zn test kit could detect, and so you could be oblivious to the existence of Zn and stand and watch as they die..

I have watched this for some time now , in one system..
Silvers and Trout would be dead in 4 days..
Now after a number of 100% water changes, the death time is more like two weeks..

I have a theory that CLAY absorbs nasties and allows them to build up, and then it can take a great deal of time to get the levels down..
All the time, KOI are most happy to live in that system

I can't see what is happening, but I am now more careful about using roof water from a Gal-Roof..

as for solving the existing problem (OP) - you could paint the inside surface with RESIN or even GelCoat

I don't think that Zn plating chemicals would be a problem, as I would be confident they would quickly wash off..
..
.

The only reason I'm even interested is because I already have the gutter, and it was free, so I'd like to find a use for it.

Sent from my C811 4G using Tapatalk

Thanks for all your help though guys, I think I'm gonna try it on the roof, and maybe just cut up a spare pvc I've got lying around somewhere.

Sent from my C811 4G using Tapatalk

So, when removing zinc to weld something galvanized, they say to mix a little flux with vinegar, and boil it, with the part you're welding in the mix, then pull it out, torch it, quench it, and then hit it with a wire wheel. If that gets off enough zinc to protect someone from metal fume fever, and screwing up your welds, that and a couple coats of paint should do for just water collection, as a safe guard.

Sent from my C811 4G using Tapatalk

Seems like a long process.

Also going to be hard to boil a gutter i imagine.

Bunnings sell 3.6m of guttering for $26. Sounds way easier to just use them.

I've done it with emt conduit and it takes right around ten minutes, and when my current job is only ten bucks an hour... It's probably gonna be cheaper for me to do that. For most people it's better to just buy the pvc gutter from a store, but I don't have a car, only a bike, and I don't make much money so I'm only allocating 200 bucks towards this. Most of which will go towards pumps and plumbing. Not to be argumentative, you guys are making loads of sense, it's just for my particular niche...

Sent from my C811 4G using Tapatalk

If you can find some spare plastic to line it with that would work and be cheap too.