Backyard Aquaponics
A place to discuss aquaponics

Even Greenpeace, who have been an avid proponent of replacing plastics with alternatives rate HDPE plastics as the next best thing to "biobased" plastics on their "plastics pyramid"....

http://archive.greenpeace.org/toxics/pv ... e/bad.html

and the only study that I've found regarding long term exposure of HDPE liners to constant water circulation and leaching found no measurable affects.....

http://www.geosynthetica.net/tech_docs/ ... Wagner.pdf

What's with the .sig then KEXIV?

Sorry, I have changed it back to my original one to avoid confusion.

One of my father's favourite sayings... it's almost a proverb at our place :-)

I need to make dividers in a few tanks for growing out different stages of growth. I was going to use "plexi-glass". Is that food safe?

Perhaps I could use HDPE sheets if they don't cost to much

Fair enough when said with tongue in cheek KP (as I believe your father uses it)- unfortunately it sometimes gets used (abused) to infer that the person telling the story is lying and that "my" version is correct - without supplying any sort of information to back the claim.

Les steps down off his soap box

I expect that HDPE can be found for a good price compared to plexi. It just might not look as cool.

plexiglass is food safe though. Drawers and shelves in refrigerators are often made out of it

I think you can all probably consol yourselfs with the fact if there is anything toxic in the system, it's more likely your fish will die first and give you good warning.
yes i'm aware things like heavy metals that might be present in recycled plastics get stored in fat and build up over time, but in all i think your pretty safe.
no point in going too crazy with chemical mania, your exposed to far worse everyday trust me.

hmmmmmm

There was a thread on here somewhere asking if there are any "Canary in the mine" style fish - ones that die when conditions aren't right. Like an early warning fish.

I'm of the opinion that we'll all be fine, breathing smog isn't good for you, and we know this, yet we have to do it anyway. I am pleased that my PVC pipes are safest of all though.

The worst part is that the fish will not be affected by the chemicals, unless of course you let them grow to their maximum size.

Most of the leachants (sp?) will be absorbed by the plants or stored in the flesh of the fish. We then eat a lot of these plants and fish, therefore our bodies have a higher concentration of said chemicals.

It is a basic nth order consumer chain. Small invertebrates and plants absorb chemicals, small fish eats many invertebrates and plant material, larger fish eats many small fish, an even bigger fish eats those, and eventually humans eat fish. So at each level of the chain the concentration of the chemicals increases exponentially.

What makes it worse is that Aquaponics is a closed loop system, which is designed to run for long periods of time. Any chemicals in there have only two ways to escape, harvesting fish or using vegetables.

I know we will not stop all chemicals, nor do the chemicals that DO exist compare at all to what we are exposed to everyday. I just believe that a system is worth doing right, and every possible step within reason should be taken to avoid possible contamination.

I thought this was interesting:

Did the reference quoted from actually specify what they considered "won't harm your fish DanD?

Not really. I guess anything that will not cause flashing is good enough for them..