Backyard Aquaponics
A place to discuss aquaponics

I am thinking galvanized fence tubing would work well for a heat exchanger; for the inner pipe, PVC for the outside pipe (counterflow concentric piping).

Is this kind of pipe safe to use for fish water? Isn't it galvanized with zinc (bad) ?

Any other alternatives that would be easily found?

Thanks for the help,
DD

wouldn't the galvanising be the same as the water tank stuff?

Hi Dave,
Gal pipe is fine, actually it is a very good idea.
Straight black steel pipe is fine also, but a bit harder to buy here in Australia anyway. That is with threaded ends and elbows etc.

The minute amounts of zinc that will come off the pipe would not be a problem.

Muzza

Not sure using Galvanised tanks and pipe is so fine. I know all Galvanised tanks I have seen used in Aquaculture have been lined with either bitumen paint or a plastic liner. Guess it depends if you want traces of zinc in your fish!!

haven't we talked about this in relation to the ph of the fliud before?

I have 2 x gal water tanks at my house that are now 25 years old, still going fine, I am not dead yet, nor am I sick.
They are actually Gal tanks (not zinkalume) inside and out with soldered joins.
They are not lined with anything except the gal.
We are not on town water, so we have been drinking and bathing in this water for 25 years, and so did our kids who have all grown up healthy and strong.
The water I use in my Aquaponics system comes out of these gal rainwater tanks.
So if the gal tanks are harmful, I better watch out, in 30 or 40 years I might die from zinc poisoning.
Muzza

my grand father was a 2 pack of 16's a day smoker and died when he was 80, so all that shit i read about smoking isnt true.

unfortunately the "i'm fine" sample group just doesn't cut it, especially when there are many variables to consider such as PH as low as 6 or as high as 8, and don't forget the bio-chelation mechanisms regarding iron that we've just been discussing.

Thanks for your reply Steve, but I think you are being a bit precious, or flippant, or whatever.
What evidence do you have that Zinc will cause difficulties of any kind, in my water tank situation and/or if used in a heat exchanger setup within a fish tank. ?
Please quote your sources, I will be interested to see them.

Muzza


Muzza

dave, I know that the high conductivity of metal seems desirable for your heat exchanger, but remember that using thick materials will result in greater longitudinal heat transfer, which will reduce the performance. What you want is in fact the thinest material you can find. If the material is only 50um thick the bulk conductivity is almost irrelevant. So look for the thinest tubing you can find. Remember that the pressure differential is going to only be 10s of cm so even very very thin materials will hold together just fine.

I bought a heated towel rail for our renovated bathroom, and it came in a 3m long polyethylene 1inch tube made from standard packaging film. See if you can find something like that.

Found thid on Zinc... Kinda why I have turned away from Zinc myself...

Even though zinc is an essential requirement for a healthy body, too much zinc can be harmful. Excessive absorption of zinc can also suppress copper and iron absorption. The free zinc ion in solution is highly toxic to plants, invertebrates, and even vertebrate fish. The Free Ion Activity Model (FIAM) is well-established in the literature, and shows that just micromolar amounts of the free ion kills some organisms. A recent example showed 6 micromolar killing 93% of all daphnia in water. Swallowing an American one cent piece (98% zinc) can also cause damage to the stomach lining due to the high solubility of the zinc ion in the acidic stomach. Zinc toxicity, mostly in the form of the ingestion of US pennies minted after 1982, is commonly fatal in dogs where it causes a severe hemolytic anemia

here's another bit

And I was happily welding the stuff last weekend

well, those two have pretty much covered it for me......................................

Yeah, I've had zinc ague or whatever. I did a whole pile of gal welding, and thought I'd got a virus. then my professional welding neighbour laughed and told me about the ague...

Lucky I was only welding 4 sections of C channel together