You’re listening to Fish Grow Plants—A podcast all about practicing and sharing the love of aquaponics; hosted by Logan Schoolcraft.
Hello, and welcome to Fish Grow Plants! In today’s episode we are answering the question, “what are aquaponic rafts?”
I’ve got a quick question to start things off with here. Have you ever thought you knew the answer to something before, but you weren’t sure, or needed a little clarification?
Well, how about this for embarrassing.
I think I was in high school, just to set the scene for you. And there was some project or activity coming up that required some extra supplies and random things. No biggie, just make sure you get it in by the end of the week type of thing.
Well, I was tasked with getting “tissues”. So, the only “tissues” I knew of, were the “tissue” paper kind that you wrapped gifts with!
This feels bad just saying it.
Well, if you can guess where this is going, I showed up with the “tissue” paper and received the most quizzical look in the world. Followed shortly by the statement, “I meant facial tissues.”
What is a facial tissue?! I wanted to know!
Well, it’s that light piece of material you blow your nose with!
That is called a Kleenex!
An awkward pause should be inserted here as the epiphany sank in to me and I realized I equated a Brand Name to an item and neglected to realize the common term for it.
So what does this have to do with aquaponic rafts you ask?
Well, I just wanted to illustrate the point that you probably already know what they are and a little clarification would solidify that so you don’t to have an awkward realization moment like I did.
Ok, enough with the embarrassing stories, let’s dive in!
Aquaponic rafts are simply the floating support structures used in a Deep Water Culture (DWC) system that allows the plants to be supported above the water, while their roots remain below.
See, pretty straight forward.
But since we are here, lets go ahead and dive into some of the details.
So, what characteristics make a good aquaponic raft? Well,
- Being sturdy
- Being insulative
- Being non-reactive
- Being non-toxic
- Being easy to handle
- Being easy to clean
- Being re-useable
- And being functional with your net pots or grow plugs
So what kind of material, or materials fit this bill? Well, it pretty much comes down to foam for most of us. Yes, I think some people have access to some natural materials that will work, but for the rest of us, we’ll be using foam; at least for the time being.
By foam, I mean extruded polystyrene (XPS) foam, or expanded polystyrene (EPS) foam.
XPS, or the extruded polystyrene foam, is the smoother looking of the two. The EPS, or expanded polystyrene foam, is the type made up of a bunch of tiny white balls (think of a Styrofoam cup; can you picture all those little balls mashed and glued together? That’s EPS foam.)
If you buy new foam, odds are, it’s going to be pure foam. That means no additives or chemical coatings that you don’t want leaching into your system water. How do you know if it’s pure foam? Well, the easiest way is if it says it right on the sheet itself. If not, the SDS (Safety Data Sheet) and the Manufacturer should be able to answer that question.
Please, do not use any other type of insulation foam or support. The common types you’ll find near the XPS and EPS are the polyiso-type foams (ISO or PIR) and they are NOT what you want. They contain chemicals that give them better life and insulation properties for construction but are lethal to your fish and plants.
Also, please don’t let a salesman tell you his type of foam is the same, without verifying the paperwork for material type hand-in-hand.
Oh, when you do buy, I’d suggest a two-inch thickness. Yes, anything over one inch will probably work fine, but when you hit the two-inch mark, you have good insulation properties, a nice rigid structure, even if using EPS foam, and you increase your options for raft sizes and shapes.
Alright, for the sake of argument, I’m assuming you are a DIY type and have some XPS foam purchased and are now wondering what to do next.
Well, it’s time to get drilling!
Or, should I say hole-sawing!
That’s right. If you’ve got your foam in hand, you now have to make it into a raft.
And you make it into a raft by cutting out holes that hold your net pots. This is where you need to be careful and do a test fit, then a test cut on one hole only.
Huh? What do I mean?
Well, a very common size of net pot used in these rafts is two inch. The only thing is, where the two inches is measured on some of these pots is debatable—and whether or not they have a lip to help hold them up.
That means you really need to check not only the size of your net pot and its lip (if it has one), but also the size of your hole saw and the size of the hole it makes.
I know that’s a lot of words, but the short of it is to test all of this by doing a practice cut and fit on one hole for one cup only. Then you will know for sure.
Once you know you have the right hole-saw and net pot combination you have to figure out how many rafts you are going to make, which impacts your construction methods.
For a commercial operation, you’d probably want a good template to mark the size of the rafts out before cutting and have an easy method for removing the foam plug from the hole saw. But if you’re getting started and looking at a mini-type system, you can probably get by with a small saw or razor blade and your hole-saw (I’ve pretty much just used a screwdriver or a long screw to dig the foam plugs out).
If you’re not sure how to space out your holes, you need to visualize the plants sitting on the rafts. Are they tall? Short? Wide? Or a mix?
I don’t know of any hard and fast rules on the hole placement, but remember to keep a good border around your holes (that is don’t put a hole within two inches of the edge of your raft). I like a nice even spacing at about six inches on center, but feel free to make some holes closer and some further apart. With a small system, you can easily change this once you see what works and what you like, or don’t like.
Fair warning. The hole-sawing can either be loads of fun or drive you mad—it’s done both to me!
Ok, lets jump ahead and assume you’ve got all your cutting and drilling done. The last step here is to coat the top surface in a good paint. Not just any paint though. An ideal paint is a “brilliant white” gloss (or semi-gloss) 100% acrylic latex exterior paint with no mold or mildew protection. The bright white color helps reflect light to the plants, the exterior grade ensures a good all-weather protection while holding up to mild cleaning, and the lack of mold and mildew inhibitors make sure you don’t leach any toxic chemicals into your water.
Be sure to coat the top, sides and slightly into the holes you drilled. The other obvious reason for painting the rafts is UV protection. So make sure if you can see it, you paint it. This goes to say you don’t have to paint the bottoms. A good quality paint should only take two coats, but a cheaper paint might require more. Then let them dry for as long as you can. I mean well more than two days—trust me. I had paint peeling off rafts because I rushed this step. Just be patient; you’ll be glad you did.
Well, that’s it in a nutshell. Actually, it’s probably more than you wanted, but one more take-away here is that you don’t have to make your own rafts anymore.
If you’re not DIY oriented, no more worries!
There are several suppliers out there more than willing to provide you rafts. Search for “aquaponic grow raft”, or “deep water culture raft boards”, or some combination of the words: aquaponics, hydroponics, deep water culture, raft, and maybe the word lettuce.
But to not leave you hanging, if you take a look at the blog, I’ve put a few links to places directly for you to check out:
So take a look if you don’t feel like going through all the effort of cutting, drilling, and painting. But no matter what choice you select, I hope the mystery of aquaponic rafts has been cleared up and maybe, just maybe you’ll give them a try…
Questions! Let me have them! Do you need clarification, more information, or maybe you just have a tangent thought—send all your thoughts my way. See the website fishgrowplants.com for episode details, or just fire off an email to email@example.com and I’ll get back to you.
So, was this episode good, bad, ugly, or other? Let me know! Comment, email, smoke-signals it doesn’t matter! I love to hear from you. Your feedback is immense, and I am always grateful for it. Likewise, thank you for taking the time to listen and share your thoughts. Have a wonderful day.
This has been another episode of Fish Grow Plants—the podcast all about practicing and sharing the love of aquaponics; hosted by Logan Schoolcraft.