Home Built Hydroponics Unit for an 8th Grade Science Classroom - The Hydroshack Lives Again!

Picture of Home Built Hydroponics Unit for an 8th Grade Science Classroom - The Hydroshack Lives Again!
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My wife teaches 8th grade science. This project "The Hydroshack" is a rendition of one I built over 20 years ago in my college teaching methods class. It is designed specifically for performing experiments in a science class. It therefore incorporates some modifications for flexibility and control purposes. It also needs to be collapsible for storage in tight quarters. If you are considering building something similar for your home, it can be less complex.

Please keep in mind that this instructable is not the only way to do this. You can build a frame from wood or PVC pipes or anything else of which your imagination can think! Your only limitations are the space your Hydroshack may occupy and the skills you bring to the project. If you are unfamiliar with welding, please use another construction technique.

Uses NFT (Nutrient Film Technique) - Nutrient solution flows along the bottom of the troughs and washes over the plants roots.
Very dense plant arrangement to accommodate 150 students in a 5' x 2' footprint
Counter top unit that breaks down to be stored above the cupboards in the classroom
Easy access to replenish and clean the nutrient tanks.
Flexible controls to allow for differing conditions: nutrient flow, nutrient solutions, lighting etc... in each trough.

Educational conditions:
The Hydroshack will be used to teach the students the "Scientific Method" (formal experimental procedures) and also be used in the genetics portion of the class. It is designed for hands on learning and assuming all goes well, will stay in production well past the completion of these units and throughout the semester.

Parameters of this Instructable:
This Instructable will feature the construction of this unit. It is not a primer for hydroponic growing. While my wife and I have done considerable research in order to design The Hydroshack to be as efficient as possible, we are not authorities on the subject. I will be making references to the process of hydroponic growing throughout this instructable, but only as a reference as to why some of the elements have been designed this way.

The numbers in each step correspond to the position of the pictures in each step. I will be presenting the construction in the most logical order, not the order in which the parts were fabricated. If you see daytime in the first picture, then it gets dark, and then returns to daylight, just run with it! :-)

Also, I had to redesign the control panel. The double gang box that was originally used did not allow us to use both timers and instead of trying to cobble together adapters and extension cords, I figured on doing it right. The sharp eyed folks out there will catch glimpses of the original control panel as the revision was made after painting.
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A cheaper alternative is Plastic fence post with holes drilled on top of A frame woodworking stands. Your setup does look nice though. I am starting with a simple rubbermaid container and spraying the bottom of the plants with a water pump, some irrigation tubing and spray heads.Plants are growing great but the cucumbers have almost too many roots.

R-A1 year ago

I'm planning on building a larger setup similar to yours. How would I be able to calculate how much water I would need?

Did you cover the rain gutters with something?
mstyle1834 years ago
the water is directly exposed to the light. which i have heard iss a big no no.. because of algea growth.. is this a problem in your garden?
RENATO.ROSS5 years ago
é uma pena não poder comercializar alguns instructable como esse!!! ficaria rico.
RENATO.ROSS5 years ago
belo progeto,muito detalhado. vou fazer um aqui no brasil com algumas modificações para o nosso pais. parabens.
Dino19816 years ago
Nice work 1st place....................
Mikey D (author)  Dino19816 years ago
Thanks Dino!
Saga7 years ago
Do a search for Rapid Rooters. They are about 1"x1"x3", around $0.26/ea. and will be great for NFT. They are an organic growth medium made of composted organic materials. Since you plan on putting a cap over the gutters, if you choose to use the Rapid Rooters you can use a hole saw to cut holes in the cap slightly smaller in diameter than the RRs and squeeze them into the holes letting the bottoms of the RRs touch the bottom and wick the nutrients("nutes"). If necessary, you can slide a toothpick through them perpendicularly to prevent them from dropping into the hole. I also suggest that you obtain a completely opaque Rubbermaid-type container for your reservoir. This will help combat algae growth. I have seen black ones at Wal-Mart and Target in the auto parts section. If you already have algae in the system you can remove it with a brush, or use hydrogen peroxide (3ml of 3% H2O2 per gallon of solution) to remove it. Best of luck!
Mikey D (author)  Saga7 years ago
Thanks Saga! We also found slotted pots for around the same price but are already far over budget. We need to be able to provide for about 150 units and this is coming out of pocket. Excellent catch on the opaque reservoir. Your idea reminded me that that is what I used quite a few years ago. I had also tried a UV light in one instance (with a dark control tank for comparison)to kill the algae, but it just made it grow quite a bit more prolifically! :-) Conceringin the H202, would you add it to the nutrient solution or just as a cleaner when changing solutions? Thanks again! Mikey
Saga Mikey D7 years ago
You can add the H2O2 directly to the nutes. Another element that mustn't be overlooked is the temperature of the nutrient solution itself. Even a difference of 5 degrees can have a dramatic effect on the growth rate. The ideal temperature is 70 degrees. A self-regulating, submersible aquarium heater can make all the difference in air conditioned classroom. I truly appreciate the out-of-pocket investment you are making in the student's lives. Hydroponics is a fantastic way to get kids engaged in a process that stimulates the mind on many levels. Huzzah!
Mikey D (author)  Saga7 years ago
I guess I need some clarification... Are you referring to keep the nutes as warm as 70 or as cool as 70. We are in Arizona and odds are the classroom is going to be warmer than 70 degrees. I have heard that cooling the nutes is better because the solution will hold more O2 as it gets cooler. Are you saying we should keep it above 70 degrees? Thanks! Mikey
Saga Mikey D7 years ago
70 is ideal. The cooler the temperature, the more the plants will edge toward a dormant state. The warmer the temps, the greater the risk of root rot or shock. Aquarium heaters are cheap. Aquarium chillers are generally more expensive. I have seen people pump nutes through the front door of a re purposed mini fridge into the freezer portion where it then ran through a coil of tubing that was placed in an aluminum meatloaf baking tin that was filled with solid ice, then back into the reservoir. While it would be much more efficient to use a copper coil instead(i.e.; for a wort chiller), any metal will react with the salts in the nutrient solution and dramatically alter the pH balance(which reminds me; your seedlings will probably do best slightly acidic, with a pH of 6, depending on what you are growing. Bump it up to pH neutral once they are established). Another low-cost method is to blow cool air over the nutrients, but however it is achieved, remember to avoid letting excessive light into the reservoir. Cheers!
Mikey D (author)  Saga7 years ago
Sounds good. When we work up the lab sheet for the students we will include temperature and PH. Do you have a low cost Ph modifier that will not adversely affect the nutrient solution? Thanks for the excellent information! Mikey
Depends on what your PH is currently. I don't reccomend using activated charcoal, for sure. Turn your eyes to the aquarium section of your local pet store, and talk to a knowledgable employee. They'll be able to steer you in the right direction.
DavidMF7 years ago
As the plants in the troughs grow wont you need some kind of bracket to keep the plant from slidind down the trough and so not to smother the roots? Great instructable!
Mikey D (author)  DavidMF7 years ago
We figure that for the experiments in the classroom, 3/4 of the plants will die. We will then redistribute the living ones (the control group) amongst the troughs. We plan on using some string from the light brackets for the plant support structure. We'll also add some white covers with holes for the stems to keep light off of the roots. Thanks David
Just get some rockwool cubes. Nicely done!
Mikey D (author)  Tool Using Animal7 years ago
Thanks TUA. We did start the seedlings in rockwool but are concerned that it will not provide enough stability as the plants mature. Thanks again, Mikey
It seems more reasonable and practical to have some sort of small container filled with rockwool (or other similarly inert material) to hold the plant. I don't see how they will be held in place in the through without something like this; the roots still need to hold on to something, or you have to have something to hold the plant from the stem. Any holey container would do, i guess, but i'm thinking the little baskes that you buy cherry tomatoes in would be particularly well suited. and, btw, great instructable and great execution. solid.
Mikey D (author)  bob.smitty7 years ago
Agreed! We plan on putting the rockwool into a container. We just need one with a low enough lip on the bottom for the nutrients to reach the roots. Thanks! Mikey
nafango227 years ago
science class. yea, im sure.
yah... damn hippies! :)
This is soo cool, I would make it but i think it's a tad too big 5 stars
Mikey D (author)  thermoelectric7 years ago
Definitely way too big for the living room! :-) However it can be scaled way down, I'd only use 2 troughs and put some space between them. In the not to distant future I am going to build one for the living room with a 2-1/4 sq ft footprint. Thanks for the stars! Mikey
Cheers Thermoelectric
Great instructable! Very comprehensive! What was the total cost, and number of hours?
Mikey D (author)  bairdwallace7 years ago
The total cost with the nutrients and rockwool was around $240. Total number of hours (this is a SWAG) is currently around 15 hours. Thanks! Mikey
BlueWeasel7 years ago
We use to make slotted cups by taking small plastic Solo drinking cups and putting holes in them with a wood burning tool. I'm hoping to rebuild/resetup my rig again soon. We were harvesting roma tomatoes faster than we could eat them. I picked over 100 habanero peppers in one harvest. I made half a gallon of pesto off of one basil plant. The nutrient formula can be a hassle to balance (I don't have a copy of what we were using anymore). South Texas heat and an outdoor setup makes for careful management of water levels between evaporation and tomatoes being VERY thirsty.
Mikey D (author)  BlueWeasel7 years ago
Excellent Blue! I tried the slotted cup idea but the nutrents didn't come up into the holes. Maybe if we had some wicking media (coconut husks for example) protruding slightly it would work better. We want to use one at home but I have already shaded all of the southern exposure windows with exterior awnings. I'm thinking of building a semi-decorative one for the living room. Thanks for the input. Mikey
You may need a higher rate of nutrient flow. We didn't have any medium in there to wick up. We spread the roots flat in the cups and holes in the bottom plus slots that went all the way down to the base let enough water in. Sometimes clay potting balls were used to hold plants up or a piece of plastic foam (like are used in pool 'noodles' would be used to center plants in the cups.
Mikey D (author)  BlueWeasel7 years ago
The volume of the nutrient flow is something I had considered. It would of course mean replacin the 1/4 poly (1/4" OD) with some larger tubing. We are germinating in rockwool which makes an excellent wick. We were hoping to use the rockwool in a cup with support medium. I was thinking of Xboogerx suggestion of gravel. I just need slots wide enough and teh rockwool deep enough (defianately touching the bottom of the trough) to allow the solution to get to the rockwool base. Thanks for the spot on hints! Mikey
Good job, Mikey. I hope the school system in your home town (city?) appreciates your extra curricular effort and talent. Today's children need more like you.
Mikey D (author)  mamasansioux7 years ago
Thank you MamaSan. Sometimes it is difficult to determine whether or not the district appreciates us. We are however teachers for the children, not the silly beauacratic adults. ;-) Thank you for the kind words. Mikey
Grey_Wolfe7 years ago
Awesome use of design to accomodate class space requirements, Mikey. Excellent project, and I hope it gets more attention from the educators around the net.
Mikey D (author)  Grey_Wolfe7 years ago
Thank you kindly Grey! Mikey
tre battle7 years ago
lol I feel ya good help lol but sadly those 8th graders wont be using this to grow roses when they are freshmen in high school
We built an entire hydroponic green house (30ftx50ft) my freshman year, and we weren't all out to grow anything inappropriate. There were a few attempts in subsequent years to try to introduce new 'crops' as it were, but it's kinda hard to hide something like that among tomatoes and zucchini.
Mikey D (author)  tre battle7 years ago
I guess this single reply will address all Y'all. Thanks for the props but we will NOT be growing herbs. Have a clean one! Mikey
Man i could have saved a boatload of money in the 8th grade if i had access to this instructable then!
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