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Fittings. Nylon, brass, polyethylene etc.

Posted: Sat May 10, 2008 3:18 pm
by Cactus Bastard
Common sense dictates that brass fittings are probably not ideal for an invert tank. Plastics are generally rather inert, and therefore a better choice.

For several months now, I have been checking all the local hardware stores every couple weeks for some really simple plastic fittings. They all carry a small selection of plastic fittings in addition to their walls of brass, but they are ALWAYS out of stock. For example, I wanted a plastic compression fitting, 3/8" tube x 3/8" NPT 90' elbow. Should be common enough? Months of searching, including two special orders that never came through, before I finally found this elbow in stock. :?

Sorry for the rant about availability... I actually came here to rant about something else entirely :roll: .

This elbow was purchased from the small section dedicated to fittings for water filter systems, and ice-maker machines (for $7 a piece). So it should be safe for my shrimp right?
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So why the hell does it have this warning on it?
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I know the "this product is horrible according to the state of california" labels are on almost everything that comes out of the states, but a fitting specifically marketed for use with drinking water systems? There is no indication what type of plastic it is made out of.

The flow through this fitting will be very low, around half a gallon per minute, but even still I doubt it would actually leach anything quickly enough to cause any problems. In other words, I'm sure it's completely safe, but I'm still frustrated. Does anybody know why these fittings have been condemned by the labs of California?

Re: Fittings. Nylon, brass, polyethylene etc.

Posted: Sat May 10, 2008 4:31 pm
by Guba
I work in the plastic industry. A lot of colors , dyes are the technical term, in plastic have varying amounts of lead in them. If you bought a fitting that is rated for "human consumption use", it generally means that any toxins in it are "insignificant". Most plastics that are opaque don't have any dye in them and are very safe. The fitting shown in your pic looks white, and white has some lead in it. Now don't freak out about this. What that means is, the lead is in concentrations low enough to not worry about. Plastic dyes are tested by the FDA for toxicity whenever a product is used for the transport or storage of food for human consumption. Additionally, the dyes are encapsulated in plastic. If they're encapsulated, then why worry about it? Well, when plastic breaks down, and it does, the pliability of the plastic degrades to the point where it becomes brittle. Brittle= cracks= more surface area= more leaching= higher concentrations of toxins. DON'T worry about your fitting for aquarium use! Taking a drink from a water fountain hooked up to plastic fittings is more toxic to you than passing 5 gallons of water through a fitting for shrimp. In my fishroom I always try to use plastic fittings! So far (since 1991), I'm hooked on the results.

Re: Fittings. Nylon, brass, polyethylene etc.

Posted: Sun May 11, 2008 1:20 pm
by Cactus Bastard
Very interesting and informative reply; thank you! :smt006

Very few fittings get replaced until they actually start leaking (which takes severe degradation). So the fact that the lead is originally encapsulated in plastic is not exactly the best solution.
I know titanium dioxide is used as white pigment in things like paint; it's also stable and cheap. What would be even cheaper to manufacture would be fittings that were not dyed at all. Most of the plastics used are already white enough on their own.

I've bought other plastic fittings manufactured by a company called JACO, which do not appear to be dyed. They've been packaged by some distribution company, and do not include the JACO part numbers or any information other than their size. When I can find them, they're also very cheap, so over time I'll try and get the white fittings replaced.

Re: Fittings. Nylon, brass, polyethylene etc.

Posted: Mon May 12, 2008 6:53 pm
by Guba
I wouldn't worry about replacing your white fittings. If they break , replace them, otherwise they are TOTALLY safe for you and inverts. Toxicity comes into play when there is NO water movement. If water sits for any time (I'm talking months here), chemicals will leach out, and then it "might" be bad for shrimp. There is no set rule that say's such and such amount of chemicals will come out of this plastic for such and such time. If these fittings are in normal household plumbing don't worry about it. If you already have plastic fittings, then your ahead of the ballgame. I have copper piping/fittings and a metal well casing to boot, and my shrimp are doing fine. It's all about water flow, if it doesn't have time to sit, it won't be as toxic. I hope this helps. :wink:

Re: Fittings. Nylon, brass, polyethylene etc.

Posted: Tue May 13, 2008 4:51 pm
by southerndesert
I had also heard about this and was never really clear on the facts and thank you all for the information!

Cheers, Bill