Water and metal/plastic compatibility

[bobert]

Hey guys!

I'm having trouble finding out the compatibility of certain metals and plastics with nutrient water. Like copper,aluminum, plastic leaching from a fitting.

This is for a cooler I'm building for hydro, but I guess can work for soil irrigation too.

There should be a sticky with a complete list of what is not safe.

Thanks!

 

[Dropped Cat]

Google is your friend, and in my opinion anything aluminum should be shunned.

 

[bobert]

I tried searching but what I found was;
Stainless steel is ok
Unleaded brass is ok, on half of the articles I find.
Copper is bad. Causes toxicity.

Why not aluminum? I couldn't find anything about it

N-g-w brand pvc pond hose off-gasses toxic chemicals.

And I'm not sure about other types of plastics or metals.

 

[St. Phatty]

Since we're sort of talking about Materials Engineering for growers ... I find one of the biggest challenges is dealing with the Sun & UV light degrading plastics & making them brittle.

I don't think any of that affects this year's crop, other than making a big mess when some piece of plastic breaks into a 1000+ pieces.

 

[MJPassion]

As far as metal containers go...


They will leach SOME with anything acidic in them.


Plastics will be a bit more difficult to research. Since the oil industry paints them to be so good for us, a lot of research can be expected to be suppressed.

 

[bobert]

I appreciate the replies!

St phatty, I've had the same experience. I try to only use food grade buckets/plastics. Not sure if it helps, but it definitely gives me peace of mind

Mj passion, that's what I found confusing. Different metals may or may not leach at different ph ranges. If I could adjust the pH to make it NOT leach, that would be awesome.

It is really hard researching this. A lot of what I find is conflicting information.

Thanks again guys!

 

[MJPassion]

pH...


Water distribution companies intentionally adjust water pH toward alkaline so that metal pipes are less affected by corrosion.


pH differences cause an electrical current to flow. This electrical current literally drags atoms along with it and is termed "electro-migration". When I was working for a semiconductor manufacturer we were working on mitigating that electro-migration withing the nano-circuits. One of my engineers was a professor on copper studies and he patented the idea that made it possible to use Cu in the chips.


You might look in that for some of those studies (I have no links) to see if you can figure out what was done in the semiconductor industry. The tech may transfer over but more than likely it will not due to the different natures of the different chemical mixtures being worked with.


IDK... It's an idea for further looking... nothing more.

 

[bobert]

Thanks, that makes sense. So soil would probably be less affected than hydro, because of the higher pH requirements.

I just read a chart about titanium corrosion. Every listed chemical had a different corrosion response, at different ph levels, at different temperatures.

I see now why there's not a list. It would take a lot of time to cross-reference what exact chemicals you're feeding, with what metal/plastic you're using. Especially when everyone feeds and grows with different items.

Didn't realize how in-depth my question was lol.