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hydroponic Hydroponics and food grade plastics

boutros

boutros

I know there is a knowledgeable bunch of hydro growers around here. I am interested in your takes on what sorts of plastics are acceptable for growing edible plants and produce hydroponically.

My basic, not complete but general understanding is types 2, 4, and 5 are "food grade" approved plastics. However, I see all sorts of plastics are involved with food.

#1 PET (Polyethylene terephthalate)*: soda bottles, oven-ready meal trays and water bottles

#2 HDPE (High-density polyethylene)*: milk bottles, detergent bottles and grocery/trash/retail bags

#3 PVC (Polyvinyl chloride): plastic food wrap, loose-leaf binders and plastic pipes

#4 LDPE (Low-density polyethylene): dry cleaning bags, produce bags and squeezable bottles

#5 PP (Polypropylene): medicine bottles, aerosol caps, drinking straws and food containers (such as yogurt, ketchup bottles and sour cream/butter/hummus tubs)

#6 PS (Polystyrene): compact disc jackets, packaging Styrofoam peanuts and plastic tableware

#7 Other: reusable water bottles, certain kinds of food containers and Tupperware

Interestingly enough, most bottled water comes in type 1 bottles which carry the disclaimer of being "one use" plastics. As in don't refill/reuse most water bottles. Or what? Chemicals leeching into your water? I've noticed that most 5 gal bottled water jugs and insulated plastic coolers of all shapes and sizes are type 7, which is the sort recently linked with and in the headlines for BPA. And I've heard a lot of negative talk about vinyls and PVC lately.

I don't have an agenda other than seeing every one's general consensus on this issue, (but am usually a big believer in you get what you pay for) and I have seen it become a fairly divisive one in some circles.

The issue has come up amongst a group of hydro growers I know, most of whom do not even grow plants that are eaten, and I figure perhaps some of these concerns have basis. What's your opinion?
 
I know to grow "organically" you can't use pvc and certain other types of plastic, as well as regular lead-lined garden hoses
 
I know that rubbermaid containers are food-grade plastic so I won't use anything else for a reservoir.

But in all honesty I hadn't given this a whole lot of thought and I'm glad you brought this up. Good question
 
Yeah it's a good thread topic, I just don't have enough to actually add to it other than maybe saying hdpe is the way to go. From my past experience with Pyrotechnicians I learned a lot about hdpe but for different reasons. It doesnt crack or break, it buldges. So over time with temperature changes and all that it wont crack on you. which is important for people who do outdoor hydro. Maybe another benefit. PVC i remember hearing bad things about from some places and no problems for others.
 
Still looking for some more hydro guys takes or additional thoughts if any from all. Have been looking around for more info. Seems to be two sides, and I guess it comes down to who you believe.

I read any plastic considered food grade is not considered food grade any longer once black dye is added to the plastic. Hmmm. What about all those black 5 gallon buckets hydro places sell then? And all my netpots are mostly black plastic.

Also read not type 2 plastic (HDPE) is not automatically food grade. Depends on the dyes they contain and if "virgin" resins were used as opposed to recycled resins.

Again, who do you believe? I have two hydro stores I go to. A laid back stoner one and a full on polished and slick business type one. The latter says, oh you don't want to use those cheap Rubbermaid containers as reservoirs, they'll leach out stuff in your water. Of course, then they'll suggest one of their $200-400 ones. Then they'll say black plastic is fine for food use. Overall, I'm sure facts take a back seat to profit. From either standpoint, there's an agenda and profit at stake I suppose.

Not trying to be too fringe, what you use is your own personal choice. Just want people's takes and not to ruffle any one's feathers. I ended up getting a few components that I plan on using in a future setup. Both carry labels purportedly designating them as containers acceptable for use as food grade containers. They lid of the garbage can has a label inside- NSF STD 2 Food contact White, Gray, Yellow. It'll make a good sized, 32 gallon reservoir. And the buckets from Home Despot have a food safe label on the side. Btw, they're more expensive, like 2-3 times more than the regular orange buckets. Unfortunately, additional steps will have to be taken for light inhibition.
IMG_2341.jpg

Anyway, hoping to hear from anyone on plastics and hydro- whatever your take is.
 
Hey Boutros,
I really don't know. I was pretty much wondering what you are wondering. I was thinking about making an earthbox for this summer but am worried about the leaching issue as well. I understand that certain plastics leach chemicals. I know you are not suppose to reuse plastic water bottles etc. What I don't know is how growing plants in those containers affect the plants. I am looking forward to seeing the answers you get. More specifically, I am wondering to what degree those chemicals are sucked up by the plants and how that affects the fruit?
 
I have just checked the 50 litre silver/ grey container im going to use for a reservoir and it has the the recycling symbol and a 5 in the middle. It also has a wine glass and fork symbol. I presume its ok then. The only problem is is not fully light proof so it may need a coat of black paint.

Chris
 
Boutros, it sounds like you are doing your homework. I've done the same searching and found that fishkeepers and winemakers have a lot of good info about what is "food grade". That's how I came across the same "Brute" trash can that you have pictured (great view btw). Although I'd like everything to be guaranteed safe, I'm not too worried about using the black 5 gallon buckets or other rubbermaid type containers with my pepper plants. I fill them up with water and let them sit in the sun for a few days first. I think that will get a lot of the residue out beforehand. I also try to keep the plastic in the shade as much as possible. Food grade or not, hot plastic can't be 100% safe.
 
Polypropylene is the safest for growing. When the raw plastics are transported, especially HDPE, LDPE, and LLDPE, use a powder to basically lubricate the pellet when it it transfered through pipes and such from railcars and tank trucks. Polypropylene is not lubrictaed this way as the raw plastic is slick in the first place. I work with most of these plastics in their raw form everyday, and the lubricating powder can be very iritating to sinus, eyes, and such.

And alot of the polypropelene pellets come in colored from the manufacturer, and dont leech out, as opposed to a dye being added when it is remelted down to make the things we use everyday. And polypropylene is also harder than other plastic so it hold up better.
 
I am of two minds, As I have used black plastic garbage bins for my water reservoirs for years. I have never thought of potential leech ?
But some how I believe if it was toxic to us , it would kill the plant first, and you would never get it to your plate.
It dose not seem to be an issue of any great substance. But I could be completely wrong.

"what dose not kill you makes you stronger" :lol:
 
Thats good to hear as my reservoir is Polypropylene. How does it handle the cold of winter? Does it go brittle?

I need to drill a couple of holes in the side and Im wondering whether its likely to split?

Chris
 
Its silver, the top is totally opaque but the rest lefts a small amount of light through. Im not sure how much usable light for algae growth can pass through.

I may have to give it a coat of black spray paint but apparently it doesn't stick well to PP. Maybe I could cover it with something else - Black white sheeting?

Chris
 
Our homemade earth tubs are mostly Rubbermaid LDPE 4 tubs. Occasionally we use another container such as wastebaskets, garbage cans, etc especially if they already have holes. We just add more holes if needed. I'm not sure how environmentally safe they are but by reusing we are keeping them out of the landfills and the price is right. The produce grown in these tubs is just fine. I try to be earth friendly with a good dose of common sense.
 
Just noticed this thread backup here...

Toleman said:
Thats good to hear as my reservoir is Polypropylene. How does it handle the cold of winter? Does it go brittle?

I need to drill a couple of holes in the side and Im wondering whether its likely to split?

Chris
Click to expand...

I would say yes if it's a gnarley winter. As for splits from holes, maybe way down the road? If it's fairly sturdt plastic, I'd just go for it. With a nice and sharp drill bit!

Toleman said:
...also the piping I have is LDPE from a hydro shop.
Click to expand...

I like my polyethylene stuff. Seems much more substantial than vinyl.
 
Toleman said:
Its silver, the top is totally opaque but the rest lefts a small amount of light through. Im not sure how much usable light for algae growth can pass through.

I may have to give it a coat of black spray paint but apparently it doesn't stick well to PP. Maybe I could cover it with something else - Black white sheeting?

Chris
Click to expand...

Forgot one! I use HVAC foil tape to cover translucent buckets and such. Looks like crap, and takes longer, but I ain't too big on paint.

I'm still on the paranoid side plastics-wise. But sorta calmed down on it a bit. Still a vinyl hater. And kinda weirded out on some stuff I've ran across from China. I guess I've been going with the basic "if it seems really cheap and $hitty, it is- don't use it" method lately.
 
Not all HDPE, LDPE and LLDPE uses anitstatic/flow powders for filling up silos or whatever. The stuff we use at work (all 3 above) are trucked in without these. Makes static cling a pita, but no nasties. I'd be more concerned about stabilizers and clours in the dyes or masterbatches leaching out in hot weather.
Also most UV stabilized products degrade after 3 years.

Most food grade/medical use plastics are made from HIPS (high impact polystyrene) PP (polypropylene) and PET (Polyethylene terephthalate).

Acids and alakais also affect the plastics molecule in differnet ways. Food grade plastics should be ok though.
 
If it's OK with the NSF in contact with potable water, it's OK with me.

Plastic paranoia discussions eventually degrade to "how many angels can dance on the head of a pin" discussions.
 
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