Backyard Aquaponics
A place to discuss aquaponics

Well yes in some circumstances.... they do harvest and pack the zip tower produce....

But in others... and TCL is the most obvious example... they transport the whole towers to the markets... and people pick and pack what they want....

Then the towers are transported back home....

I think you'll find TCL will DEFINITELY disagree with you....

And when you say "LIVE SALAD"... do you in fact mean a "live" lettuce.... or do you mean a bunch of various lettuces etc... that people just "murder"... and rip apart... to select a salad mix....

P.S.... from the photos of your market stall.... I didn't see anything that could be referred to as "live"...

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I've reviewed the technical manuals I have on LDPE, HDPE and PVC (in many of its forms).

Please remember that some of these details are specific to particular manufacturers so there is a chance that based on the research we have both done that we might be both right even if our research has delivered contradictory results.

"LDPE materials may be modified with elastomers (rubber modified)" states the Vinidex PE manual which is possibly a phthalate, I'll have to check. But why would you use LDPE plumbing fittings?
The LDPE products that interest me are LDPE liners. Very tough, relatively flexible and UV resistant. I'll have to check if they have phthalates added. I had the impression that they did not and their flexibility was the result of the carbon chains making up the polymer.

My understanding was that rigid PVC did not contain phthalates since their purpose is to make plastics flexible. Flexible PVC on the other hand, for example food grade flexible hoses and all PVC liners, are loaded with phthalates to make these products flexible because without a Plasticiser PVC is rigid.

HDPE is the best choice of materials for pipes that are exposed to UV and is the reason why you will see HDPE pipes used in many applications where pipes are laid above ground. In below ground applications PVC is used because it is more cost effective. In Australia it appears that normal PVC is PVC-U (ie pvc used in regular pressure pipe and DWV). Furthermore "The PVC compounds with the greatest short-term and long-term strengths are those that contain no plasticisers and the minimum of compounding ingredients. This type of PVC is known as UPVC or PVC-U."

Also "Although PVC pipe can be installed in direct sunlight, it will be affected by ultra-violet light which tends to discolour the pipe and can cause a loss of impact strength." This results in the pipes becoming brittle and susceptible to cracking.

HDPE are not prone to these problems (they have some others) and there is also not the added health risk of being exposed to the glues during installation.

The ability to recycle HDPE products is part of the reason they are a more sustainable product. Sooner or later pipe systems are scraped. Even if that is in one hundred years at that time the disposal of those pipes will become an issue.

You say "build once enjoy twice" by that philosophy I would chose HDPE as the material for my plumbing, as indeed I have.

Wonder what sort of environmental nasties are in the foam used in the raft beds....

All sorts especially the fire retardant.

If using poly styrene rafts best to coat them in some why. Paint on poly urethane is the best choice I have found but there are some acrylic options that I have had suggested to me. Still need to look into those but the PU option seems fine once it has cured.

Humm... ABS is Acrylonitrile Butadiene Styrene..... usually 40-60% Styrene.....

Wonder if it's really environmentally friendly...

Opened a can of worms there Janna!

I think its horses for courses, flexible ribbed pond hoses are good for connecting pumps especially submersible ones.

The pump is easily removed and can be moved around if required.

long pipes with few fittings are usually cheaper in PE, while complicated short pipes with lots of fittings may be more precise and economical in PVC,

PVC will get brittle after exposure to UV, maybe not a problem in Holland!

I find it funny how people freak out over unmeasurable amount of chemicals leaching from plastics
when they ingest a million times that amount of chemicals walking down the street!

Ah, worms, also a very interesting topic, but I didn't mean to open a can of them here :-)

HDPE being the best option chimes in with what I already read (I just hadn't considered it for other than growbed). I am going to research avaiability and price of it.

Or by breathing the fumes from the car exhaust pipes.... that we carefully aim towards us as pedestrians... and our babies in prams...

Just to keep the thread veering off-topic, I love the idea of "live" food at the marketplace. There's a great little farm down the road from us that does CSA boxes and has a market for local produce/meat/dairy and value-added products (jams, pickles, etc.). I think having a nice looking little aquaponic display system you could stock with lettuce heads, herbs, and whatnot would be great marketing. You wouldn't have to grow it in place, but just put the plants in as needed.

My wife works on the farm one morning a week in exchange for a big box of produce. Great deal, I believe.

I don't think Janna opened much of a can of worms. This sort of discussion is one of the really valuable aspects of the forum.

If Janna can supply his research to demonstrate his point then I wold be grateful. Espeacially before I shell out the $10k for the HDPE welding gear. One of the reasons that I decided to go with HDPE is that I was under the impression that PVC was banned in potable water systems in the EU. Since one of our first interested customers for a system is an EU company we decided to meet EU standards because they are more strict than Australia's. Now I may have that wrong since Janna is in the UK but then the UK is only sort of in the EU.

HDPE is not an economic option for the backyarder because of the cost of welding equipment and/or the cost of the fittings if using screw compression fittings or push fit fittings.

As I have no plans to go commercial, I haven't really researched legal aspects of the use of PVC. And I am actually in continental EU, not in the UK.

The screw couplings do seem fairly expensive, but if you can re-use them if you change your system, I wouldn't mind that. Since HDPE doesn't release anything as much nasties as PVC when it is burned at the end of its useful life (we have no landfill here) I am actually considering it seriously for part of the system. I'll have to see if I can get it in my budget.

As I am in the posession of, as geek2nurse put it in her thread "wimpy girl muscles" (hope I quoted that correctly) I also look for something that isn't too hard on those muscles. Those screw fittings might be a challenge for me, which would count against them. Purchasing welding equipment for an AP system is out of the question, bur we do have a neighbour plumber.... mmmm..... wonder if he likes fish....

You know as I was typing "his" I thought "why am I assuming Janna is a boy?" Just my innate sexism showing through.

The screw fittings can be tightened with a stilsen. As long as you don't go overboard the ribs on the screw fittings will get chewed up a little but not too much if you are careful.

Yes, a stilson would probably be the way to go.



I guess most members her are men and I've seen someone with the username Jayendra (if I am correct) who indicates that he is male, so Janna could very well have been a male. But she isn't

Maybe more men than women get excited about the building and technical aspects of AP? Not me, I am sure to like every aspect of it. Already am a vegetable grower, general tinkerer and I tremendously enjoy chemical processes and making them work for me. even something as simple as seeing a bread dough rise. I'm sure to watch the fish long and often and, though I don't look forward to killing them, I will eat them with pleasure.

I've been a bit daunted by dough. I built an oven a few months ago and we have cooked some really delicious food but the whole sour dough process is not something I have gathered the mental head space to do yet.

I have used hdpe pipe and fittings throughout my system, including the GBs, FT & ST. Pipe and plumbing fittings have cost over $1200 so far, and I'll have to spend a bit more as I add another 4GBs, but there has been no need for any welding at all, since fittings are available for everything I've needed to do.