HydroponicsOur Projects

Floating Raft Deep Water Culture

Author: Jared Bouck

Project Cost: 20.00
Est Construction Time: 1.5 Hr
Required Skill Level: Can you use scissors safely?

So I’ve been on a hydroponics kick it seems lately. it’s not that I’m some sort of vegan hippy tree hugger… I still play with my Arduino’s, blow stuff up and have midnight raves with led’s. But there is something just captivating with watching the grass grow. This project has to be my favorite hydroponic project so far. Not because its technically difficult, it’s not. Not because I’m breaking down walls of intellectual bullshit so anyone at home can do it. Not even because its oxygenating my office, but that’s a nice perk. No I have to say this is my favorite hydroponic project because of the results. It takes about 4 weeks to go from seed to sea of edible green! The rate of growth for this is insane. Anyone can do this at home and definitely its practical indoors or outdoors. yep this can be scaled up big time. Perhaps I will… Try this one!

For this project we will be using a lot of parts. There is a lot of flexibility in what materials you can use. However, for the main tub that we will be using you may need to do a little hunting. For this project you need to find a tub that has straight walls all the way to the bottom. If they are tapered you will have the foam not sit right and you can get problems from roots drying out to algae. Also… once you find the right tub, if its clear then paint it black.

Next we will be using some construction foam insulation. The main reason we prefer this is that it is not going to pollute our water and more over it is laminated front and back with a plastic film that adds to strength a great deal. You can find this very cheap at any home improvement store.

Now to hit ebay. I picked up this set of 2 inch online for about $5.00. 2 inch seems to be ideal for both the size of plan but also the Rockwool we will be using.

Here we have our Rockwool cubes. Every time I use this stuff I am impressed more and more. Simple, clean, disposable and very effective. This helps plants root well and retain moisture that especially young plants need. These are 2 inch cubes. Make sure to soak these in a low ph solution per the manufacturer’s instructions for best results.

Here we have a simple 2 output 9 dollar aquarium pump. We will use one of these for each tub/raft we make to oxygenate the water and keep it from stagnating.

For this project we will need about 10-15 feet of cheap aquarium air hoses. Make sure you also get some check valves to prevent any flooding problems if a pump dies.

Finally we have some air stones. These simply plug into the air hose and produce a steady stream of fine bubbles. This is deal compared to just dumping the air hoses in and letting them make big useless bubbles.

So now we start the project. Here I have set my tub on a piece of the foam I want to cut. As I need to both round the corners and cut it to fit it’s a good idea to trace the outline of the tub and then cut inside that the width of the rim of the tub to make a good fit. For cutting this I tried several tools but finally settled on using an electric meat carver.

Next we will layout out net cups on the foam to get a feel for where and how many we should use. As a rule of thumb I had a gap ranging from 2-3 inches. For the larger lettuces I wished it was consistent at 3 inches in hind sight.

With our net cups laid out and marked we will now need to cut our holes for the net cups. For this step I used a 1-7/8th hole saw. But it was a little sloppy cutting through the light weight foam. Not of the net cups fall through but it’s not as nice as I would like. Perhaps the next time I try this I will try to use a hotwire cutter method.  

Here we can see the final product. Yep this is the only part of the project that actually requires any real thought and effort. So if you can’t make this… then… ummm… why are you here? You know we want you to actually try this crap right? It’s one thing to learn about cool shit, but it’s another things entirely to actually do it.

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Understands, Creates and fixes really cool stuff.

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Here we can see how the net cups should be placed into the foam raft.

Next we setup our air lines for the bubblers. This pic shows the check valves. Make sure you pay attention to the direction of flow arrows on the side of them or you may be disappointed.

And now we have the air lines attached to our pumps. Hurray for step by step!

Here we have our pump setup with our lines running into the tub. We don’t need to anchor down the tubes as the stones will keep them on the bottom and shortly roots will hold them in place.

Now its time to start preparing for production. Here I have filled the tubs with water. Surprisingly it was almost exactly 5 gallons to fill this up. Make sure you have the thickness of the foam  left over after filling this up so it will float flush with the rim. We used our general hydroponics  simple recirculation setup for this with the seedling amounts of nutrients.

Here we can see the foam floating on the water with some net cups. Yay for net cups!

And now the final setup. We are using this indoors in a grow tent we picked up on eBay. Check out our other hydroponic projects for lighting and tent help if you want to do this indoors ( no pests! ) or of course you can do this outside as well, just watch out for other creatures wanting to eat your almost but not quite hard work.

Now we move onto starting our seeds. After soaking our Rockwool we placed 3 seeds in each cube and left them to germinate for 3 days. For our first run we used Oakleaf looseleaf and Bibb Butterhead salad greens.

Here we have our seeds in a simple jiffy sprouting greenhouse. While not critical, it will help speed things up.

Ok, so from this point on things move fast. Here we have our seeds sprouted. We need to cull the sprouts. I hate this task for some reason. I love to see my seeds sprout. But if we want big full plants we have to remove competition and weak plants.  We do this simply by pulling out the smallest seedlings from the Rockwool.

Now normally I like to have my sprouts in a higher humidity environment to start off, but I took a risk and went ahead and planted them in the tent. The one nice thing about DWC systems is they never will run dry. Here I simply placed the Rockwool cubes into the net cups (after removing the plastic wrapper). Then I tested to insure the ph was still looking ok for the plants.

1 week after sprouting. Now, with the lights on a full 24 hour cycle we wait. But  we don’t have to wait long. Make sure every few days to check in on the plants and make sure they look ok and haven’t lost to much water. Now usually when I do DWC I have had plants that take longer to grow like tomatoes. These slower growing plants require you to get up to high concentrations of nutrients and to change the water frequently. For this setup I simply slowly added more nutrients as the plants developed increasing the concentration over time. Within one month I was able to harvest with no nutrient flush. When you’re done feel free to use the water in your garden or on your lawn. Don’t just dump it down the drain.

HOLY CRAP! That is 4 weeks to the day from seed to salad. Yep my grow tent overflowith.

So here we have the end result. These tubs are overflowing with great green healthy and yep, flavorful greens!

Here we have our hydroponically grown oakleaf looseleaf greens ready to start harvesting.

Here we have our hydroponically grown Bibb Butterhead Lettuce ready to start harvesting.

And now a nice light snack. Here we have a nice salad of hydroponically grown greens and tomatoes. Add a little cucumber from the garden and some poppy seed dressing and you have a wonderful byte that is more fresh and full of nutrition that anything you will see in the supermarket.  Oh, and one more note from the author… see the tomatoes. See how they are deep red all the way through. You wouldn’t believe what a real vine ripe tomato tastes like. Our supermarket tomatoes are picked green and gassed to ripen them and they never develop in flavor or nutritional value. This is good honest real food.

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I am in many respects the text book example of someone who shouldn’t be successful. I was an outcast in my grade school years, and a poor performer in school, unable to fit the standard mold. Fortunately I found small opportunities that I took advantage of, and coupled with hard work they have guided me to where I am today. I spend my time running several businesses I own, developing new products and sharing what I have accomplished with those that deserve opportunities that they wouldn't get any other way. InventGeek has been a step on a path that has helped bring me success and confidence by the simple act of doing. I encourage our readers to do what they can to better themselves a little each day, because overtime it's amazing what you can do!


  1. Avatar
    October 27, 2015 at 8:40 am — Reply

    may I use coco coir or any similar kind as substitue in medium?
    hope for your response as possible

    • Inventgeek
      November 5, 2015 at 1:12 pm — Reply

      Any medium will work fine. Its just what I liked to use.

  2. Avatar
    Mehdi Maqboub
    January 5, 2016 at 3:39 pm — Reply

    The biggest boston (dome) lettuce factory in the world is close to where I live in Montreal and they said in a news report that they never change the water, it flows and gets oxygen from the pumps and they replace the water that the vegetables absorb but that’s it.

    How is that possible ? Wouldn’t the water get filthy after a while ?

  3. Inventgeek
    January 20, 2016 at 12:25 pm — Reply

    Yep it would become a mess. But this is a common practice. They simply run the water through sand based filters to remove particulates from it. That could be dead roots, algae, dirt and dust or chelated nutrient solution. This is a common practice also in aquaponics. They don’t feed the actual fish waste to the plants, they filter it and then allow the water soluble nutrients to feed the plants.

  4. Avatar
    July 30, 2017 at 1:05 am — Reply

    hi. what were the measurements of your tub in terms of length, width and depth?

    What was the measurements of your foam board and how much did it cost?

    Whats ph is best?

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