Hardware Store Hydroponics

Science fiction movies often portray horticulture in the future, be it terrestrial or aboard spacecraft, with hydroponic gardens overflowing with leafy greens and brightly colored fruit. There is no soil, just clear water that hints at future-people creating a utopia of plant strains untethered from their earthly roots.

This star-faring food production method is not fiction if you forego the polycarbonate tubing, neon accent lights, and gardening robots. For his 2020 Hackaday Prize entry, [AVR] shares how he creates a bed for sixteen plants with parts sourced at a nearby home-improvement store. It may lack the visual pizzaz of the Hollywood versions, but it will grow soil-less crops on a hacker budget.

The starting point for this build is a sturdy wooden base. The PVC tubing and fence parts on top are light, but the water inside them will get heavy, and if you grow large plants, they become surprisingly heavy. Speaking of water, the sub-category of hydroponics this falls under is Nutrient Film Technique, or NFT, which uses a shallow stream of water laden with all the nutrients for plant growth. The square fence posts provide a flat top for mounting mesh cups where the plants grow and a flat bottom where the stream continuously flows. A basin and pump keep the plants refreshed and fed until they are ready for harvest.

33 thoughts on “Hardware Store Hydroponics

  1. I’ve been starting to wonder why SF shows that appear to have a severe strawberry shortage don’t seem to have anybody turning to hydroponic gardening to deal with the problem. Perhaps one of the unfinished Firefly episodes had Kaylee trying to fill her room with tubes full of strawberry plants?

    1. I can just hear the argument with Mal now.. ‘If you wanted to be a dirt farmer I can drop you on some planet, you’re hear to make the ship work, not play with plants…’

  2. I like the idea but all that PVC. Non-food grade PVC (vs uPVC) may also have additives with BPA or other toxins. It looks like everything about this is PVC which is cheap but healthy?

      1. if growing weed it’s no big deal but it looks like veggies are growing so safety should be considered. Reality bites but we’re a bunch of geeks so a solution should be possible.

        1. It is a very good point, but I don’t think you need to be that concerned away from using PVC in this role unless you are deliberately sourcing a really toxic PVC blend… It might well leech a poison or two into the water that is picked up by the plants – but that is no different to the poisons deliberately sprayed by farmers, leeching into the soil from waste sites, or the mineral soup we all breath etc etc.. We are exposed to lots of nasty all the time, as long as you don’t dose yourself up on something really nasty really fast it will be hard to notice the change.

          I wonder how long even the most toxic leeching PVC would take under those conditions to have ‘nothing’ nasty left in it… Probably quite fast I would think, even quicker if the water is changed for ‘clean’ water often.
          Or if the plants would uptake meaningful amounts of it.

        2. If you were growing weed legally the requirements are 10 times stricter than any food grade or FDA approved methods. Many cook with cannabis but its even more dangerous to inhale any type of chemicals especially if consumed through combustion so 100% not okay with weed either. Obviously you dont smoke or medicate. This is a cool concept but in the end just that. They sell this set up on ebay out of safe pvc material and have for about a decade for around 200 bucks. Why waste your time building it plus the material. Some people have way too much time on their hands.

      2. now please go in your basement or crawl space or utility area . look at the pipes your drinking from
        and the purple primer that’s code for potable water pvc pipes

        if you ever water your garden from a hose its the same

          1. Yes – for sprinklers for lawn and garden irrigation are all PVC with regular or purple glue. In CA they still sell the red hot pvc glue and purple primer. I just bought some last week for a new sprinkler line.

          2. I remember Thailand: You get beautiful skyblue PVC pipe from 1/ inch or less up to 20cm or more. The same material is used for water supply and for wastewater lines. Although I do not know, how many people there drink tap water anyway.
            But hard PVC is quite safe and stable.

        1. With respect to big difference between my water supply pipes and a hydroponic system is the hydroponic system is essentially closed. That water and the toxins in it aren’t going anywhere they’re not getting flushed out. They have two ultimate destinations the plant or they just keep cycling through.

          The water in your water supply pipes only goes through your pipes from your well to your glass. Which is a much smaller and shorter duration. Just understand the difference between why a long-lived fish like a tuna has more Mercury than a short-lived fish like a tilapia.

    1. PVC does not contain BPA and hard PVC does not contain softeners which could leech out. The pVC pipes are probably for home water supply, so they should be food safe.
      Against residues of the glue I would flush the system before the first use.

    2. I read his BOM and some of the log to identify the pipe he is using. The exact version he bought from Lowe’s seems to have been supplanted, but it is described as “Schedule 40” and “NSF”. The same with the purple primer and cement. A bit of research suggests that, at least in the US, all such materials have to be suitable for potable water, and Lowes only stock one type, from Oatley. This is the case in the UK too, in that any PVC pipe for domestic use must be suitable for potable water. This seems to have started over 20 years ago and must have been due to plumbers using which ever is cheaper, and not reading the instructions! It might also be that manufacturers save costs if they only use one sort of PVC for pipe and fittings.

      So my reading of this is that the PVS piping is not an issue. Wether this is true of the fence posts is another thing. I haven’t been able to find anything definite. Would there be regulations about plastics used in outdoor structures leaching into the soil?

      He also states that this started as a test bed for a low cost HydroPWNics project, but ended up as a project in it’s own right.

    3. Having done a fair bit of aquaponics in the past, the biggest concern I had was PVC pipe that used lead as a stabilizer. In the US at least, that type of PVC is typically only made into DWV (Drain, Waste, Vent) pipe, not the hard white stuff at your local big box. Trouble is, the really large DWV pipe is very attractive for use in vertical systems, and that’s where you get trouble. The more acidic nutrient solutions can leach lead out of those pipes.

      From the looks of the picture above, I wouldn’t worry about the pipes themselves, but the “PVC fence posts” being used for the NFT “beds”… They have no intent of being used to carry drinking water and are much less “guaranteed to be food safe.” A quick call/email to the manufacturer should be able to clear that up pretty easily though.

    4. I actually made a business at one point out of building, selling, and filling a small ecosystem for plants. There ARE many challenges. I went to GREAT LENGTHS to use all food grade material. The issue with that is the cost. Many people don’t want to pay the 600 bucks for the parts, labour, fill, seeds, etc. Despite the fact that it will save them money, and be healthier and taste better.

      However, the results are amazing. I put it on wheels, had a composting tube in the middle with access for worms, a special fill that is great for worm bedding, and feeds the mycelium, over 50 plants in less than 3ft x 3ft. it’s up off the ground so you never have to bend down to work, the water that comes out of the bottom is recycled back into the thing. it’s draught resistant. You can use it indoors or outside. The longer you use it, the better the soil gets. I accounted for micronutrients and trace minerals as well. The whole thing is on wheels and is easy to roll around, even when wet. It mimics a natural water table for the roots to reach to with great drainage. I LITERALLY thought of everything and incorporated it into a single standing garden on wheels. It can’t be any easier. You can literally get endless salads out of it if you just planted leafy greens. Best part, little to no weed pulling.

      But good luck selling people on the fact that it’s 100% food grade materials, comes with a 1 year warranty, cost includes delivery and setup, etc, etc, etc. They just don’t do the math on the health benefits vs. that grocery store crap that COVERED IN PESTICIDES and may contain pharmaceuticals from ‘organic fertilizer’ that’s really made from human waste that’s not processed by anything that breaks down those chemicals. (watch gardeners buy that crap from the big box stores all day labeled “organic” but it’s really just crap they pulled out of a sewage processing plant)

      There are so many challenges because people just don’t realize how many facets there are to real healthy food. And I DEFINITELY wouldn’t use pvc not rated for fresh water, it breaks down in sunlight very rapidly. HDPE is probably the most stable that we can use without too many issues, and considering the fact that most people are exposed to that anyway, it shouldn’t do anything harmful when your plants are exposed to small amounts of it.

      Hydroponics are flawed in the sense that they require too many inputs and you are essentially trying to take over and do the job that mycelium and a healthy micro-biome will do automatically. I understand the fascination with them, I still think it’s fun to try out a few different types here and there. They are super fun for indoor plants like a single plant vase for some spices or whatever. But when you want to feed yourself and don’t want to put a crap ton of work into it, you need the ENTIRE ECOSYSTEM, not just a fascimilie that you just throw water and some industrial nutrients over. If you’re gonna do that, might as well start by using the spare bathtub, or use a swimming pool. I like to spend more time harvesting and less time fiddling around with the nutrients, etc. But it’s much easier to start by building a composter and throw your food waste in there with some yard clippings/leaves/carbon of some sort, then use that for your soil. At least it’s not human feces.

  3. Save all that PVC and sealing at the return/low side by using holes at the very end/bottom of the rows and put another section of square tubing under the lowest side with a single hole in the bottom over your tank. Us a funnel or something to get the water into a small hole in the lid of the tank. Get rid of the air pump too, the falling liquid will aerate just fine. You can even notch the top of this return catcher sq tubing so the row sq tubing fits into slots and help hold the rows in place. Ziptie each row into place.

    1. I’d probably stick with the plumbing or some other way of enclosing the nutrient solution. Nutrient solutions like to grow algae and you *really* want to keep the light away from the nutrient because of that. Algae growth does a couple of bad things to your system: 1) it eats the nutrients that you paid for and want to go to your plants 2) it affects your Ph 3) get enough and you start clogging things. PVC blocks just enough light that it is much more difficult for the algae to grow. I’d still spray paint the pipes black though.

      1. Using square channel with notches would keep things enclosed. I was just concerned with the rubber sealing required in the OP design but see that “slip joint” also allows for fluid level adjustments. I don’t know how much that’s required after experimentation. Was just thinking a larger spillway into a larger catchment below would simplify things.

          1. No worries. I just started and built a small 9 cup self contained hydroponics garden 2 months ago and have been eating lettuce and french radishes from it. I’d read a bunch on this, not all by any means, and have heard how important it is to keep sunlight off the fluids to keep algae grown down. Spray painted the lid and outside of my 4 gallon self contained unit. It’s an indoor unit.

            I’m going to give this larger version a try using rain gutter down spout for all the rows and for the return runs as I described. I have an old pallet to put something on so that’ll be the base along with some cement blocks.

    1. You probably mean a “National” plumbing code. I don’t know about the existing of an international one. Not even in the EU is a EU wide plumbing code but many national.

  4. Many, many moons ago I saw a project published that was almost identical to this, and in my zeal went to Lowe’s (they have the “fence posts” used here, whereas Home Depot does not), and a weed-growing (excuse me, “hydroponics”) store, and stocked up on all the components needed to construct it. They are still way too much occupying space in my garage, and I long ago lost the plans for the setup. Now I am inspired to go back to it and actually make it work, especially when I am reluctant to go grocery shopping very often. Thanks!

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