liner leaching

[kevin darcy]

Hi

I am considering buying a roll of 800 gauge high density polyethylene to line my growbeds, is 800 gauge heavy enough?  i'll be using pea gravel as grow media,a roll of (HDPE) is very expensive,  i want to use plastic or rubber pond liner but i was concerned about the plastic leaching into the water!,  does rubber leach?  would leaching in ap systems gb or ft liner's hinder AP farmers from obtaining an organic cert?. thank you.

[Greener]

good to hear about the EPDM cycling, thanks. I will check out the 100 gal Rubbermaids. $70 a pop is higher than I was hoping, but given the lifetime I know it's worth it.

[TCLynx]

I'm still searching for a more cost effective grow bed container but I'm having a hard time finding anything better.

[Greener]

arrgg I just had a long reply deleted... here goes again (condensed):

The black Rubbermaids do look like the best deal around, thanks. These are made from Structural Foam though (a recycled plastic material, I think) -- does anyone know if this material is food safe? (link?) Also, are these heavy-duty Rubbermaids UV-resistant? I assume they are, though the adds I'm seeing don't specify that.

Anyone know if polypropylene (PP) is food safe? I saw some large, cheap PP containers for sale today.

Is HDPE #2 food safe, but not the plain 'HDPE'? I found some great, cheap HDPE tupperware-like containers at Home Depot, but I doubt these are safe to use in the long run (price is too good to be true).

Finally, can anyone add to the PVC leaching discussion? I've always assumed that PVC was food/water safe!

So many chemicals to worry about...

[TCLynx]

With most plastics, getting the "food safe" USDA rating doesn't necessarily depend on the specific type of plastic but proving to the "certification" that there are no "dangerous" chemicals used in the manufacture that will leach into the food. Unfortunately, there are plenty of things that leach into foods from "food safe" materials!!!!!!!

So the question is going to be, what are your reasons for wanting "food safe" materials? Are you wanting it because you are planning a commercial operation and you want organic certification? Or are you after stuff that doesn't leach anything? Or are you just trying to be safe?

The Rubbermaids are safe enough for aquaculture. I don't think they have the USDA food safe rating but that may not mean that they are unsafe, it could simply mean they just never spent the money to get the certification.

As to What plastics are food safe or drinking water safe, There is some PP that is used for drinking water and HDPE is generally thought to be the safest of plastics.

As to the "food safe" that leach the nasty things that the government isn't protecting us from, that would be mainly the clear, transparent, and most flexible of plastics. The plasticizers that allow for flexibility and transparency seem to be some of the worst.

On the PVC front, PVC pipe is drinking water safe, well at least the drinking water pipe is. But PVC is also used for flexible products like vinyl liners and those I definitely find suspect on the plasticizer front even if they are rated as "food safe"

[Greener]

TCLynx you are a wealth of info, thanks!

My reason is to simply get as far away from the nasties as I can. Let's go with the organic-certifiable level as the benchmark.

About HDPE, do you think one of those large, tupperware-like HDPE bins (without mention of food-grade) from Home Depot would cut it? These can be found big enough for GBs and are very inexpensive. Or is there a higher-level HDPE I should stick to?

I will try to get more info about the Structured Foam/recycled plastics question. I think the Rubbermaids must be good enough for certification if they are sold as animal feed/watering tanks..

[Greener]

Here's another 100 gal GB option, a little more expensive but marketed as UV-resistant LDPE that meets both USDA and FDA requirements (like I know what those are..).

http://www.usplastic.com/catalog/item.aspx?itemid=36717&catid=641

However it also says "designed for containment of liquids of up to 1.5 specific gravity." Given that I will be filling this large tank with gravel and then water and plants, does this mean the tank won't be able to hold up to all that weight?

I'm planning on calling Rubbermaid and asking some questions about their Structured Foam. I'll let you know what I hear.

[Greener]

I just called Rubbermaid Commercial and asked about their Structured Foam (SF) products. Apparently all of their SF products are made of the same material, HDPE with no other plastics mixed (though they didn't specifically say 100% HDPE). These tanks do NOT contain UV stabilizers but they say that the black color should provide enough UV protection for the tanks to last years outside (hopefully this is true; I suppose you could always paint the outside if you were worried about lifetime). These tanks do not have any agency approvals (FDA, USDA) and are not 'recommended' for food use. They are intended for watering of livestock and Rubbermaid makes no claim for other uses (the lady said that it could be that these products are actually fine for food use but that they just haven't been tested/certified yet). I can find other Rubbermaid SF products that ARE both FDA and USDA compliant (like these: http://www.rubbermaidforless.com/material-handling-storage-tilt-tru... ), so if all of their SF products are really made from the same material then I would expect the SF tanks to be complaint too, if they were ever tested like the SF tilt trucks (anyone disagree?).

I'm now totally convinced that these Rubbermaid SF tanks are the best all-around GB option (at least, when price is an issue). I'm looking forward to the 24" bed depth too. For those that don't want to go so deep though, they make a 50 gal version that is about the same area as the 100 gal but only half as deep. How convenient.

Anyway thanks again TCLynx for pointing me towards these products!

[TCLynx]

Yep Greener, that is often the case that a company will use most of the same materials in their different products. They can't claim food safe because they haven't paid for the certification process but unless you are actually storing post harvest food stuff in them, I don't think you have to worry about it either. (lets face it, dirt is not certified food safe either but most of our food is grown in it.)

I had resisted the stock tanks in the beginning myself but after the problems with termites and the lumber/liner beds, I'll not go using liner in connection with wood anymore. I'll still use liners but they will be supported by dirt, metal or concrete. For normal gravel grow beds, the 100 gallon stock tanks are a good height/shape and not too bad a price for the gallons.

[Greener]

TCLynx - do you use liners in the Rubbermaid GBs?

I'm hoping to avoid the liner all together, was planning on filling the RMs directly with gravel.

[TCLynx]

No, I don't use liners in the plastic stock tanks. I just plumb through them with 1 1/2" uniseals, set them on 5 leveled concrete blocks, arrange the gravel guard and fill them with gravel. Start flowing water through and good to go.

Greener said:

TCLynx - do you use liners in the Rubbermaid GBs?

I'm hoping to avoid the liner all together, was planning on filling the RMs directly with gravel.

[Greener]

I spent the morning calling around and searching online for the cheapest Rubbermaids (for my GBs). The $70/100 gal online option is a joke once you include shipping (unless you get 10 at once). The best I'm finding locally are going for around $1/gallon. I suppose this is as good as it gets.

Any reason not to go with the 150 gal models? They're the same depth as the 100s, but provide a larger growing area.

I've also spent a while trying to locate inexpensive food-grade IBCs, locally. Very difficult to find at a reasonable price. Any suggestions there? I have calls and emails in to all the big bottling plants around.

TCLynx - what do you use for your fish tanks again?

[TCLynx]

I have one fish tank made of some fence panels and EPDM liner, that one is about 700 gallons.
I have another fish tank that is a 300 gallon rubbermaid stock tank sunk in the ground about 2/3 rd of the way.
I have a fingerling tank that is a 100 gallon rubbermaid.

As to where to get the rubbermaid stock tanks. Your local Tractor Supply store will probably be the only place you will find them at the lowest prices without having to pay additional shipping.