Conversation about Aquaponics

Paul said someone should start a new thread on aquaponics, and as far as I can see, no one else has started one, so here goes!  I'm interested -- read the Australian site yesterday, and would like to know more.  I'll take a look at their forum when I get a chance (I've got to plant potatoes, since I cut them up yesterday!), but have a couple of thoughts/questions.  It looks like it should be possible to build your own set up for quite a bit less than the Aussie guy sells his for.  I would use gravity-feed as much as possible (our land has a slight slope, so I should be able to set up a gravity-feed system with a solar pump to return the water).  I'm thinking maybe ferro-cement, but would that be okay for the fish?  I'll have to do some research to see what fish would work best here.

And it looks like it should be possible to add some other things to the system, like ducks and rabbits.  Chickens?  Earthworm beds?  Beds of marsh-loving perennials following the annual vegetables?  What else?  How to optimize production and minimize inputs?  I'm thinking of setting it up in a manner similar to a gray-water purification system....

We live in a dry climate (with cold winters), so anything that reduced the amount of water needed to grow food would be a good thing.  And reducing weeding would also be a good thing!

Kathleen

Is there a difference between hydroponics and aquaponics?  At first I thought you meant aeroponics, but that certainly doesn't seem very permie, and would probably not enjoy worm castings plugging the sprayers.

There is a community on the east side of the cascades, here in washington state called "windward".  I've never been there, but I read their web page and have tried to arrange a simple visit or tour several times and have failed.  But I did manage to talk to one of the founding members there for an hour or two on the phone. 

So, here is the fascinating thing:  They got one of those refrigerated trailers that you pull behind a semi truck.  They made it the roof for a greenhouse. 

The funny thing about refrigeration is that it is effectively extracting heat from the space that you want to be cooler.  So they take that heat and put it in the greenhouse.  So now they have a walk-in freezer and loads of heat for the greenhouse.

You might think:  but doesn't the heat pump use fuel?  Yes, yes, it does.  But it is all fuel that they have created on their land.  I cannot remember if they are doing a methane digester or extracting wood gas. 

Inside the greenhouse, they have an aquaponics operation setup.  The plan is to keep the greenhouse at a constant 86 degrees. 

I've always had this grand idea of pairing fossil-fuel power plants with greenhouses.  It only makes sense--the waste products of one (CO2, H20 and heat) are the feedstocks of the other.    Then my pessimistic side says, "If that worked, someone would have done it by now".  I wonder how many brilliant ideas are delayed by that mantra....

Ryan Lenz

doughpat wrote:
I've always had this grand idea of pairing fossil-fuel power plants with greenhouses.  It only makes sense--the waste products of one (CO2, H20 and heat) are the feedstocks of the other.    Then my pessimistic side says, "If that worked, someone would have done it by now".  I wonder how many brilliant ideas are delayed by that mantra....

Ryan Lenz

Ryan, I believe there are several greenhouses with just such a set-up in villages in Alaska, where vegetables mostly have to be flown in, and are very expensive.  Since electricity in those locations is generated by (also expensive) flown-in diesel, they want to get as much good from it as possible.  At least one village that I know of uses the waste heat from their generator to pipe hot water heat to all the houses in the village. 

Paul, that's an interesting idea.  I'd be interested to see pictures of that set-up -- I'm having a hard time visualizing a refrigerated container as a roof!  Wouldn't it work just as well as the back wall?

Kathleen

Check out Joel Malcolm's site, Backyard Aquaponics, it's great!
http://backyardaquaponics.com/

He has veggie grow beds and fish tanks.  He pumps the poopy water from the fish tanks and runs it through the grow beds.  The plants absorb the nutrients from the water, cleansing it, and then the water returns to the fish tanks, over and over.

You can use anything of a suitable size, but the units he sells are so good-looking that you could have them in the entrance to the front of your home.

I've watched him grow from the basic idea to a full-fledged business over the last several years.  He has an online magazine, information, and a discussion board.

Sue

Susan-
Thanks for that link, Joel's site is very interesting.  I've always wanted to install a small Tilapia pond that would irrigate my raised beds via a drip system--maybe this will prove to me that it is in indeed possible! 

Ryan

Hay there, I'm new here but definitely been around for a little while over on the backyardaquaponics forum (BYAP)  If you are thinking of trying your hand at it, that forum will definitely help you out!!!

Joel's kits are nice and you get the benefit of a "kit" type system and all the support they give but you can certainly DIY aquaponics, I know I did since ordering a system from Joel would have killed me on the shipping

If you have a nice slope to your land, definitely use it, It can really make for some good AP set ups.  Also, I highly recommend looking up CHIFT PIST over on the BYAP forum since it can mean a good amount of effort saved on cleaning the pump trap every few days (this is me kicking myself for not doing a CHIFT PIST system) fish poo and bio slime really can clog things quickly.  In a CHIFT PIST system, the water is pumped from a sump tank as the lowest point in the system up to the fish tank.  The fish tank is set up to over flow and carry solids into the grow beds where the gravel and earth worms can filter it and the plants then use the nutrients then the water can auto-siphon back down to the sump tank being much cleaned and ready to be pumped back up to the fish.

I've got about 90 some catfish and 80 some tilapia in my AP system and I'd better go out and tie up the tomatoes before they block the path and start charging a toll.   

Hey Kathleen, like TCLynx above this post I'm pretty active in aquaponics and the backyardaquaponics.com forum.

To address your points specifically:

It looks like it should be possible to build your own set up for quite a bit less than the Aussie guy sells his for.  I would use gravity-feed as much as possible (our land has a slight slope, so I should be able to set up a gravity-feed system with a solar pump to return the water).

Totally possible.  I'd say the vast majority of people make a custom system.

I'm thinking maybe ferro-cement, but would that be okay for the fish?

IMHO, the jury is still out on unlined ferro-cement.  There's a guy in El Salvador using them, and he's having unexplained problems.  One cause might be the lye in the cement altering pH and leaching into the system.  If you line the ferro-cement with something already known to be fish-safe, you should be golden.

And it looks like it should be possible to add some other things to the system, like ducks and rabbits.  Chickens?  Earthworm beds?  Beds of marsh-loving perennials following the annual vegetables?  What else?  How to optimize production and minimize inputs?

All have been done, successfully, and are continuing to be researched by individuals in their own systems.  Compost worms will even live in your growbeds without any soil!  There's lots of people trying different things, especially to make the fish feed as sustainable as possible.  In aquaponics we are usually dealing with stocking densities higher than you would find in a natural pond.  As a result, we generally have to feed the fish in addition to whatever might naturally be in such a pond like algae, smaller fish, water plants, etc.

Some things people have tried out have included worms from vermicomposting, spent brewer's yeast, oatmeal, black spider fly larvae, and others I'm sure I'm forgetting.

I'm thinking of setting it up in a manner similar to a gray-water purification system....

That can definitely work.  The only caveat I would add is that when I think gray-water I think marsh plants.  When I think aquaponics, I think more food productive plants.

Regarding concrete...

When concrete is mostly cured (a minimum of 28 days), it is quite alkaline.  To reduce the alkalinity (and I don't know how long it takes), you have to repeatedly rinse or soak the concrete in water, then pour it off, repeat, etc.

EVENTUALLY, it will lower the alkalinity level so acid-loving plants can be grown in a concrete planter, but it's not a quick process.

One thing I can say is that I made some concrete spheres in summer.  I had to keep them damp so they would cure properly without cracking.  I filled up my dog's rigid plastic wading pool and put the spheres in it, then covered them with old towels that hung into the water and drew moisture upwards to keep the sphere's wet.

That water stayed clear for a LONG TIME!  And I didn't even completely clean all the existing algae from inside, just put some water in it and scrubbed it with a broom and called it good.  The algae never even thought of growing.

Sue

And it looks like it should be possible to add some other things to the system, like ducks and rabbits.  Chickens?  Earthworm beds?  Beds of marsh-loving perennials following the annual vegetables?  What else?  How to optimize production and minimize inputs?

It should be noted that when adding warm blooded animals into a closed recirculating system like aquaponics, you need to be more careful of possible food borne pathogens like salmonella and e. coli.  I'm not saying it can't be done but I am saying to do some extra research on those subjects before building your chicken roosts over the fish tank.

That said, there is a Duckaponics thread over on the BYAP forum (this started more so the owner of it could have nice clean water for the ducks and it worked out that filtering the duckpond water through the gravel grow beds made for much better smelling and looking duck pond without having to change out (waste) water all the time.  I believe that member has also gone on to build an actual separate fish growing Aquaponics system.

Trying to incorporate all the different animals into the same AP system might be more trouble than it's worth with all the extra variables likely to cause fish die off or other problem.

I definitely thing composting worms in the grow beds are a must (that is my personal opinion.)  then one could set up the worm composting pit under the rabbit hutches to have even more worms around for feeding to the fish and chickens.

Personally, I think I would save the chicken waste for regular composting, too hot for the worms and not really appropriate in a recirculating aquaculture system for the most part. 

I know in many pond culture sort of Aquaculture systems, they use manure (often chicken) to induce an algae bloom in the pond and the fish eat the algae.  This can work in a large body of water but still needs to be carefully managed as if the algae bloom gets too out of control, it can crash and cause major problems with pH and dissolved Oxygen and in turn cause a major fish die off.  Some people have been trying to figure out how to do the algae bloom feeding in Aquaponics but most of us avoid large algae blooms in our systems if we can since algae tends to cause daily swings in the pH and dissolved oxygen levels which are usually hard on fish, plants and bio-filter bacteria.  Plus the algae uses up much of the nutrients we were trying to have for the veggies we want growing in the grow beds.

Anyway, Aquaponics is great and a wonderful way to have animal protein growing in your own back yard even if you live in the burbs and arn't allowed other livestock!  It is also a great way to grow veggies even if you can't utilize the soil (like if you live on a barren concrete lot, don't laugh, I have seen some completely concreted in back yards before.)  An aquaponic system is also a really handy place to root cuttings.

That all sounds like good advice!

The advantage with using fish in the system rather than larger animals is the size and amount of their poop!  Larger animals have more solid poops, which would probably have to be mixed to liquify.  And you would probably need a larger setup to compensate for the larger amount.

Unless someone can offer a really brilliant idea, it appears that fish may be the best creature for aquaponics.  Larger animals would seem to complicate the system.  JMO.

Sue

Aquaponics really is for the fish.  If you want a ponics for another animal, then I suggest the simplest way is to build a ponics just for them (like duckaponics for keeping their pond pleasant since they have such a way of being foul )  This way you can keep things simple enough to keep things balanced yet harness the nutrients in their waste.  Then again, if you have enough space and can simply put in a real pond, it could be a moot point.

TCLynx,

Can you upload some pics of your system?

Hum, I haven't figured out how to upload pictures to this forum but I already have a whole system thread available online over at the BYAP forum.  That full system thread is over 70 pages long but take heart, I post lots of pictures so it isn't as long a read as one might fear.
http://backyardaquaponics.com/forum/viewtopic.php?f=18&t=2640
I can link a few images here from that and from my web site.
http://www.aquaponics.tclynx.com/
This image is from last spring before I even lined one of the fish tanks

And this picture is after some major changes and the addition of some NFT pipes being fed by water that is already filtered by a couple grow beds


There is an article about my system in the BackyardAquaponics Mag that is available online
http://www.byapmagazine.com/

Quick system stats
aprox 900 gallons worth of fish tank volume though the biggest tank fluctuates in level.
aprox 1500 gallons of flood and drain gravel beds
Media is a mixture of river pebbles and washed sea shells along with some red lava rock in a few places
Pump runs continuously and flood and drain is managed with auto-siphons for the most part and a couple other tricks also tested out.  One giant grow bed is right on the ground and required a pump on a float switch to drain it once flooded, this pump feeds the NFT pipes and any other needs for well filtered water to avoid clogging with fish poo.
Currently I have about 165 fish in the system.  Channel Catfish and Blue Tilapia. 

Let me see If I have a good pic form just lately to upload as the tomatoes have really turned into a jungle lately.

hay there, I know this is a rather old thread to bump but...

I'm planning a free workshop where I'm going to expand one of my aquaponics systems and give others a chance to get a little hands on experience if they wish.
It is planned for December 11 and 12 from 10-4 with pot luck lunch. My place is near Mount Dora Florida

Here is a link to more information for those who are interested.
http://www.aquaponiclynx.com/workshop-dec-1112-2010

That site also is gaining more pictures of my systems and there are two videos to look at too if you are interested.

Been working on my system a bit. 

Here's the growbed support I built:



Scrubbing out the growbeds:



Future new sump tank because the present one isn't deep enough:



Setup.  There will be more growbeds along the side:



I'll be raising Bluegill and Channel Catfish, which I hope to order in the Fall. 

A couple updates.

New sump tank:



Floating islands planted with Chard, Lettuce and Basil:

Got the new growbeds installed, so far these aren't leaking.  They're a little wonky from the barrel having been distorted by sitting around half-filled with water for about 5 years,  but seem to be working out.  I  temporarily rigged the pump tubing to fill the barrels and put the floating islands in.  The lettuce seems to be doing especially well.

whats the rule of thumb for reusing containers as growbeds or FT? I have a source from a local car wash offering as many as i can take. Many say Poison and I dont feel awesome about the thought of my food contacting them. If algae is allowed to bloom, does that mean its ok?

Personally I wouldn't use any container marked "poison."  Seems like a rule of thumb might be "Don't use any container marked 'poison'." 

Basil, chard and lettuce growing well:

Got a couple more tanks and moved things around a bit.



Why is there always a giant rock right where I want my sump tank to be?

Hello
This is a lot of great information and I am seriously considering making the effort but I still have quite a few questions.  I have five elderly people to feed on one acre if things take a greater downturn.  700 000 new coops in Britain just last year.  Wow

Here's a link about diseases and stuff about tilapia

http://edis.ifas.ufl.edu/fa012

When I collect the crap runoff from the fish tank is it sufficient to collect it from the top?  It floats?  I don't need to vacuum the bottom?  Any bottom will do or do I need several inches of stone?

Tilapia are tropical so it doesn't matter how hot the water gets in my Florida tank?
What about on freezing nights?

I read and reread above that scum algae uses the oxygen that the fish need so I want to avoid it but  what if I have another dirty tank using human sewage for the growth medium.  How big would that tank have to be to grow enough algae to feed the fish?

What is a good size for 250 1 lb tilapia?  They eat two percent of the body weight per day in three feedings but how would I measure algae?  Should I dry it first for a better measure and to prevent it from growing inside the fish tank and to disinfect it from any germs in the dirty water?

I saw a tube where they fish crap runoff is kept for five days for the nitrogen to set.  Just letting it sit there 'sets' the nitrogen?  They kept scum out of that tank because it eats nutrients that they want for their grow beds.  How is that done?  (They run a tour and answer these questions but it's fifty bucks!).  Do they stir up the water before flooding the beds or do they filter the heavier stuff out or do they just flow it all in there and have a paper filter on the outflow pump?

I can eat lettuce but there are no calories for me or my chickens.  Can corn be grown easily or is it difficult for some reason?  Would it be better to plant corn in the ground and use a drip heavy in particulate?  Wouldn't a drip line with crap in it plug often?

Should I order stock fingerlings all male or should I include a few females or does it matter?

I planted my garden very late to take advantage of the summer rain but then got no fruits on the tomatoes, the squash and the cucumbers although they flowered.  Was it because they were out of the normal grow cycle?  Rabbits may have got to them so I am not sure.  Does seasonal cycle matter in grow beds that don't freeze and have some sun?

Thanks already

Here are some answers based on what I've learned so far (I'm a beginner):

When I collect the crap runoff from the fish tank is it sufficient to collect it from the top?  It floats?  I don't need to vacuum the bottom? Any bottom will do or do I need several inches of stone?

I'm using Solids Lifting Overflow Siphons, which help bring up crud from the bottom of the tank.  Not putting any gravel on the bottom helps the SLO keep the bottom clean of muck.  I'll try to take a snapshot of my siphons for you.

 

Tilapia are tropical so it doesn't matter how hot the water gets in my Florida tank?
What about on freezing nights?

According to this site: http://www.aquaticcommunity.com/tilapia/tankculture.php  Tilapia prefer water temps of 82-86F and will die below 50F, so you'll need to heat the tank in cold weather.

I read and reread above that scum algae uses the oxygen that the fish need so I want to avoid it but  what if I have another dirty tank using human sewage for the growth medium.  How big would that tank have to be to grow enough algae to feed the fish?

I'm guessing you mean for your human sewage tank to not be actually part of the aquaponics system, but a separate tank.  I can't speak to how large it should be, personally I would avoid any kind of open tank of human sewage but instead suggest either worm composting or subsurface-fed reed beds.

What is a good size for 250 1 lb tilapia? 

Backyard Aquaponics and Practical Aquaponics recommend a 1:1 or better a 2:1 ratio of growbed to fish tank volume.  1 lb of fish to 5 gallons of water is recommended, so for 250 pounds of tilapia you would need a total water volume of 1250 gallons, with half or more of it in growbed volume.  The larger the system the better as larger water volumes are easier to keep stable in terms of nutrients and ph and also change temperature more slowly, which is easier on the fish.

More about growbeds in aquaponics: http://aquaponics.net.au/blog/learn-about-aquaponics/grow-beds-in-home-aquaponics-system

I saw a tube where they fish crap runoff is kept for five days for the nitrogen to set. 

This isn't necessary if you use media-filled growbeds.  If you're only using water-filled growbeds with floating islands, you'll need to have a biological filter somewhere in the system.  This might just be as simple as adding some gravel to the bottoms of your island beds.  Most people use media-filled beds, it seems.  I'm planning to have both.

I can eat lettuce but there are no calories for me or my chickens.  Can corn be grown easily or is it difficult for some reason?  Would it be better to plant corn in the ground and use a drip heavy in particulate?  Wouldn't a drip line with crap in it plug often?

Personally I wouldn't bother with corn in the aquaponics system, there just isn't sufficient room for such a large plant and you'd need a huge volume of growbeds to produce sufficient calories.  Personally I'd look at the fish for calories and maybe also grow some fruit such as melons.  Extending your system to include poultry, rabbits, or guinea pigs gives more opportunities for calorie production.

Should I order stock fingerlings all male or should I include a few females or does it matter?

I don't know. 

I planted my garden very late to take advantage of the summer rain but then got no fruits on the tomatoes, the squash and the cucumbers although they flowered.  Was it because they were out of the normal grow cycle?  Rabbits may have got to them so I am not sure.  Does seasonal cycle matter in grow beds that don't freeze and have some sun?

Temperature affects pollination, especially in tomatoes.  You might not have enough local pollinators to do a good job on the squash and cukes so maybe next year try hand-pollinating and/or grow a lot of flowers to attract bees and other pollinators.  You  probably won't have to worry about rabbits in the aquaponics system!

Hope this helps.  Like I said, I'm just a beginner, but want to be helpful to other beginners. If I've gotten any of the above wrong, I hope a non-beginner will correct my info!

Lots of help at Practical Aquaponics http://aquaponics.net.au/blog/ and Backyard Aquaponics http://backyardaquaponics.com/forum/index.php

Yes Ludi that was very helpful
I tried to ask some questions that I didn't know and others might be interested in and I think you filled it out nicely
Thanks

Another way to pump that water is a hydrolic ram pump, you had said the property is slopped and if the fall is great enough a ram pump works great and under its own power.

Here is the start of a 12' x 100' system I am working on, I am using the old root cellar (14L x 10W x 7 deep) for the tank. Its about 5000 gal and made of concrete.

60' of the frame completed

Wow!  You're very fortunate to have that large "tank"! 

H Ludi Tyler wrote:
Wow!  You're very fortunate to have that large "tank"!   

Yeah, never hurts to get lucky! lol.. This land was a mess when we got it, guess it was a old junk yard of sorts. That "tank" was full of burned trash from the old house in the pic and was also full of water. It is about the size of a dump truck bed and had to shovel it all out by hand.. WHAT A CHORE! I already have fish started in it and it holds temp and water very well, I plan on making the seed starting area above it and between the "tank" and house will be the nursery greenhouse. Cant wait to have it all done but it does take some time as you all know  Wish the permie powers that be would make a section just for aquaponics

you gotta post some progress pics then!

This is a system my friend made, has a 300 gal fish tank that over flows from the cycle to a sump tank. Above he has grow beds as well as a fingerling tank. I will get a updated pic, this pic was early spring and the system was incomplete. System sits against his his house in a 12 x 20 south facing greenhouse.

Current progress of that system

I have been switching between wanting aquaponics and not thinking it makes sense for awhile.  We had a system going for awhile in our house where we had goldfish that were feeding two grow beds.  I had a system design for a small commercial greenhouse similar to growing power but after I had finished the design I had second thoughts.  For our farm systems I always come back to is this place better off than when we started.  The question its self is totally subjective since every person has a different meaning for improving or at least little to no impact. 

I couldn't find a way that made doing it work for us.  When your using the grow beds you're removing a lot of soil biology that normally would interact with the plants.  Does that have an effect on the benefits the plants offer im not sure.  You are avoiding tilling but we have permanent no till beds so thats not affected.  You can grow more calories in a small space which could mean that you are having less impact.  But most folks who are doing aquaponics use a commercial fish food which is a by product of the large commercial fish industry that are destroying fish populations.  They also include different agriculture products that are grown far away then heavily processed then sent to you.  Increasing your gardens global footprint. You can supplement your fish food with BSF or duckweed but they don't meet the full protein requirements for the fish to keep up good growth. 

Then there is the whole plastic problem.  You may be growing in a smaller space but with all the plastic piping and tanks the chemical foot print your garden is using increasing dramatically.  Most of the plastic is PVC which is a pretty nasty thing to make and has lots of toxic by products.  Its made far away in villages that we dont have a relationship with so we can still feel like we are not making a big impact. 

Im sure there is a way to make it work out so the pros heavily outweigh the cons hopefully someone here can point them out to me.

jbreezy wrote:

Im sure there is a way to make it work out so the pros heavily outweigh the cons hopefully someone here can point them out to me.

I think some (most? all?) of the evil is outweighed by producing one's food at home.  Especially if one can grow the fish food at home. 

In-ground natural ponds would be preferable but not everyone can have such a thing, especially in town.

I worry about the perfect being the enemy of the good in this case, and people being ok with driving to the store to buy packaged industrial food to avoid the evil of buying plastic tanks and a little pvc to raise fish and vegetables in their backyard. 

As an aside, one could use bamboo in place of the pvc.  And a lot of people make most or all of their systems from recycled materials. 

Ok, here goes my 2 cents...

"When your using the grow beds you're removing a lot of soil biology that normally would interact with the plants.  Does that have an effect on the benefits the plants offer im not sure."
In reality and IMO your not prohibiting this relationship, using creek gravel or clay it acts as a filter for the solids and bacteria will grow and break these solids down, after all it is organic matter. Plus adding compost worms to the system will really boost this eco system. As far as the health of the plant or the nutrition content of the plant that is decided by what you feed your fish, dirt farming is no different its what you feed the soil. Example would be this. The plant absorbs what is in its "soil", so you have an organic carrot that was fed compost, the compost came from a commercial non organic farm. That farms soil has been depleated and no longer contains the trace minerals, so the compost contains no trace elements so your carrot does not either. If you feed those tops to the tilapia your system will not contain the minerals either. Same goes with the crappy commercial fish food. But if you are feeding your fish wholsome nutrient DENSE food (from your garden), your system will contain the same thru the fish waste. Another Suggestion would be seaweed if your by a coast, this stuff is packed with trace minerals so I read. As far as getting protein there are several ways, make a 5gal bucket and put fish endtrails in it, drill holes near the bottom the let the maggots drop into tank. Vent out the roof of greenhouse, just got to get creative.

"You can grow more calories in a small space which could mean that you are having less impact."
This IS the case with aquaponics, in dirt you are limited by many factors and space is one. Space is a factor due to these factors, 1.) nutrients and 2.)water. There are only so much available nutrients and water supply per sq ft. In a aquaponics system you are really only restricted by actual space and light, your water and nutrient supply is never ending and thus elimitating the peaks and vallys associated with soil. This boosts growth and increases production ALOT.

"But most folks who are doing aquaponics use a commercial fish food which is a by product of the large commercial fish industry that are destroying fish populations.  They also include different agriculture products that are grown far away then heavily processed then sent to you. 
You can supplement your fish food with BSF or duckweed but they don't meet the full protein requirements for the fish to keep up good growth." 

Again, the maggots are a good choice to suppliment as well as black fly. Duckweed is still pretty high in protein @45%

"Then there is the whole plastic problem.  You may be growing in a smaller space but with all the plastic piping and tanks the chemical foot print your garden is using increasing dramatically.  Most of the plastic is PVC which is a pretty nasty thing to make and has lots of toxic by products.  Its made far away in villages that we dont have a relationship with so we can still feel like we are not making a big impact."

You can use poly tubing, copper or steel. I totally understand here and PVC is not the best choice at all, it off gasses some pretty bad stuff. I personally use poly tubing, over the life of this tubing in the system (forever) the benefits WAY out weigh the "cost". Permaculturally speaking this is a good thing.

Does anyone agree or disagree?

I hope this helps and provokes some thoughts 

Also wanted to add that the grow beds can be made from 2x12 lumber or plywood with a pond liner, this dramaticlly reduces the amout of plastic for the beds.