Grow beds

[Andrew Cope]

hello,

I use half 55g blue barrels in a flood and dain with valves going to every single one and it is a pain to say the least.  does any one have any cheap alternatives I was thing about buiding a grow bed and using the pond liner I already have thats never been out of the package, but if I did that from scrach it woud be kind of expensive since those liners are about eighty something at home depote.

[Tom Dumas]

William a few people use billboard tarps instead of pond-liners. They are much cheaper and you can build a bed the size and shape you want.  Not as much plumbing needed.  I think the website is billboardtarps.com.    Tom

[Andrew Cope]

Thanks Tom,

 

I will def check that out.  And I quess for the structure use wood with two  by twelves for the sides.  plywood for the bottoe and four by fours for the legs.   Thanks again !

[Jon Parr]

There is controversy regarding billboard plastic leaching nasty Schmidt. Vlad knows his plastics, and Vlad says "no". That's pretty near gospel. 

There are cheaper pond liners than the 45 mil EPDM. Personally, I like DuraSkrim. I think it is wise to have each barrel feed a DWC bed immediately adjacent. Or, use big drain pipe, plenty of vents, and cross your fingers that they don't all siphon at once. 

[Averan]

I discovered an even better option: https://www.btlliners.com/

And I disagree with the conclusion on billboard tarps. Plastics like PVC billboard tarps do most of their offgassing/leaching right after manufacture. Used billboard tarps have already spent time sitting out in the sun, wind and rain and have leached and offgassed most of the volatiles. Billboard tarps being pvc, will photo-degrade, but are covered in a UV protectant layer (made of what though?) and if covered by gravel or shaded by rafts should last at least 6+ years. When cost is an issue and if you are using PVC plumbing anyways, then it's pretty hard to turn around and argue against used billboard tarp as a valid lining material. Of course PE is better than PVC which imo is better than EPDM, so if you can afford the upfront expense, go for the best.

To be clear, there is another kind of 'billboard' tarp that you can get from printing shops like Staples and Kinkos where they print big photo signs and such, those are another kind of plastic and stink like crazy. I don't know what they're made of but they seem to be much more toxic/leachy than the used billboard tarps at www.billboardtarps.com.

My current order of preference =

1. BTL Liners

2. Used Billboard Tarp (cheap) or Duraskrim (maybe safer, but more $)

3. EPDM

[Vlad Jovanovic]

..."...When cost is an issue and if you are using PVC plumbing anyways, then it's pretty hard to turn around and argue against used billboard tarp as a valid lining material..."

Averan, comparing u-PVC (your plumbing) to m-PVC (billboard tarp) is like saying is like saying that the Grandma from the Beverly Hillbillies looks the same as Sasha Grey because they are both female...

Your rigid PVC pipe is ridgid and contains no pthalates. ALL FLEXIBLE PVC LINER CONTAINS PTHALATES THAT WILL AND DO LEACH RIGID PVC u-PVC PIPING DOES NOT. 

It is the PTHALATE PLASTICIZERS that are the problem with PVC liners and not any type of "volitiles" (unless you count the manufacturing process itself as a problem). 

I'm really not sure why we have to go over this for the 8,368th time...but don't confuse the issue for other folks, rigid PVC and flexible PVC ARE NOT COMPARABLE. There is a reason why industry, even in the US, is phasing out the use of pthalate plasticizes in food containers, childrens toys, personal care product packaging, adult sex toys, hospital IV bags etc...In many other places on the planet their use in certain applications has been outright banned.

It's not an "opinion" of mine, nor is it "something that I came up with"...according to the laws of physics (and every inorganic chemist on the planet), the reason pthalates leech from the flexible PVC that it has been added to, is that on a molecular level, no covalent bond can exist between it and the rigid PVC it has been added to in order to make it pliable.

Of course you are free to use whatever material(s) you like...hell, you can use the 'recycled' bricks from the Fukushima reactor for your media for all I care...that is your prerogative...but please don't sell 'apples as oranges' for the rest of the folks out here in 'AP internetland'. 

I sincerely hope that you did not get into AP because you thought it was a cheap or inexpensive way to grow some food...

Btw...how was it that you came to the conclusion that the billboard liner sold at Staples and Kinkos was "more toxic/leachy" than the ones sold at bbs.com"...?

Again, rigid vinyl piping and pliable vinyl liner are two different beasts. It has nothing to do with the 'off gassing of volitiles"...

[Averan]

My spidey sense detects a wee bit of hostility! I'm happy to learn from someone who knows better than I but I can do without the borderline insulting tones.

I'm pretty sure I made it clear that it is not the best, ideal or safest material, but I do believe it is perfectly acceptable in some situations.

Thank you for your clarification on the difference in types of PVC. I'll ignore your exasperation and aggression for the time being because I assume you don't understand that not every AP gardener has read your previous posts on the subject and therefore any time someone posts to the contrary it is not a personal insult to yourself.

Everything I have read about leaching mentions copper, UV and heat. Well, we're not using copper fittings. UV is blocked due to media or rafts. And generally our water temps are much cooler than the warm/hot water tested in home plumbing. I agree pthalates = bad. However, they break down quickly in sunlight, anaerobic conditions and biologically. The most dangerous source of pthalates seems to be from either drinking water from a plastic container (non PE) or breathing vapors from degrading offgassing plastics. Since we don't drink AP water that source isn't a concern. And since used billboard tarp has already done most of it's initial release of pthalates and other volatiles and since we have it covered up out of the sun and air I suspect it is not going to dump much more into our systems. Every source I've read tells me that pthalates (being unbonded and just hanging out amongst PVC molecules) are released when the plastic itself is degraded. My argument was that in an aquaponic situation I don't think there's much degradation occuring. I may be wrong since I have no data, but I thought it necessary to add a rationale counterpoint to the extreme anti-billboard tarp sentiments and point out that the reality is quite possibly not so extreme.

If you have the cash, go for the best/safest material you can afford. If you don't, I think used tarp and EPDM are acceptable, although not ideal.

My comment on Staples and Kinkos signs/tarps was based purely on conjecture and observation from a colleague's experience. Fresh billboard tarp might very well smell just as bad.

For the record, there are pthalates in most 'rigid' PVC pipe too. That is changing now though, as you mentioned. And, dimethyl and diethyl pthalate are both quite volatile so offgassing has a lot to do with it.

[Vlad Jovanovic]

Nope, no hostility and nothing personal Averan. The caps are just there to emphasize some of the pertinent points, since you seem to have omitted them in your analysis of pliable vinyl. 

As long as you believe that its perfectly acceptable, I guess that's what counts. We all need to make our own decisions.

Btw. u-PVC contains none of the problematic additives. (Hence the "u" designation).