Raft/Deep Water Culture Growers

Aloha !

Here are a couple more pics to give you better idea.

The GM Raft System

This design is fricking awesome...I'm growing lettuce almost  2x faster than regular foam rafts and cause the only part of the raft that touches water is the 2" pontoon there is lots of aeration underneath the root system (WITHOUT) the need of air stones, valves, siphoning or any other device.

Is very simple concept that works great, I'm sure whoever tries it will love it and is less than 1/2 the cost of the foam rafts and  about 75% less work without the mess and once you get one going you can make a bunch at a time.

I used 3 screw at the ends and 4 on the sides, make sure to use stainless

Have fun...

So the improved oxygen level is in the water? Due to the air contacting a much greater surface area (no rafts blocking the air)? Or does it have something to do with the pots suspended above the water in the air? Any chance you have a DO meter?

Sorry for all the questions - love your innovations. The old saying is "Necessity is the mother of invention!"

Top of the day to you aquaponeurs. I have read many articles and have the aquaponics bible with Sylvia's contribution, I can not find what my tank water amonia level should be after cycling. My sytsom cycled a few weeks back, amonia and nitrites are almost non existing while my nitrates are high. I have read this is good sign, and that I need to add more grow bed vegetation. Sould I see signs of amonia after the pond cycled ?

My comment should have gone to disscusion, my bad.

Giorgio,

Thanks for sharing you're design. I was in Kauai not too long ago and toured the aquaponic center at the college there. The guy there, did something similar but he but the poxy on top of the styrofoam board and he said that it was healthier for the plants because of the air gap. I like your idea better I'm not a fan of styrofoam.  I was going to buy the foam boards last week, glad I didn't. 

I'm designing my raft bed at a 12" deep can I get by with a shallower bed?

This may be off topic,  but I am setting up a DWC system in a GH.  My ideas are getting a huge pvc ditch drain,  soldering the ends up with plastic,  and doing it that way,  whats the difference if i fill it with gravel or just letting water flow ?   on one end i want to put three fittings above each other,  so i can raise and lower the water level  if needed. 

Chris, I am having a little trouble visualizing  what you are proposing. Could you elaborate or post a diagram?

Hi all..Am just getting started re AP. Want to do a raft system for lettuce/ greens. Have a good sized (thruflow) fish pond with over a hundred tilapia in it. Plan to solar pump the water up to holding tanks and then circulate it thru 24 growing trays which descend the hillside in a greenhouse situation. Looking at 4 rows of six trays-  (12" deep,16" wide, 24" long). My question (among many others) is what would be a good flow rate for the water- or what size pump is needed for a system this size?

Rick, a good flow rate is 2 -3 gallons per minute. Pump sizing is going to depend significantly on how far you have to lift the water.  Many pumps will have more flow and less lift than you need. One piece of free advice - if you're pumping up to your fish pond (as I do to my tank), arrange the outlet so the water sprays or fountains up and then falls - this aerates it.

thanks much Kate..will be pumping up from fish pond to holding tanks,then gravity feed thru trays back to (with areation) the fish ponds. Because I'll be solar pumping what will happen if I reduce the flow at nitetime so I don't need to use battery  power? Water needs to flow 24/7?

Like Giorgios idea re pontoons on the rafts rather than foam..Roots getting air should be a good thing -correct? 

sorry meant to add that my holding tanks are about 800 gallons so could use that daytime stored extra fish pond water to trickle flow thru growing trays at nite- at perhaps a slower rate?

another question?? How does it work re the top trays getting more nutrients than the trays lower down in the system? need to occasionally switch bottom trays to top? Rotate? Or? 

well, I like to maintain circulation 24/7. If you're getting aeration this way, as I am, you need it as much at night as by day, and it ensures that nutrients and O2 are always mixed. Turning pumps on and off can be hard on them, or they can lose prime. That said, some kind of short power-cycling to save electricity is worthwhile if your pump is good with that - many people do it. And if your pump can go low-high instead of on-off, that could be the best.The plants can be stagnant for a day or 2 with no harm; fish need O2 24/7.

As to top vs. bottom trays - I have long troughs, and I don't see any difference in nutrients between water fresh out of the fish tank and water going back in. Friendlys report the same.

Pontoons vs. rafts - seems like they both work well.

On my page about halfway down is a drawing of our layout. How does ground water maintain O levels? ?? Fish have been living in parts of those ponds for some years now. We intend to widen and deepen the ponds so that we can support a larger population of fish. And will areate on the return from the growing trays. And experiment some with food.Have large filters for the water entering the holding tanks tho may need to filter the water before entering the pump.

(Lived for over 30 years in the islands and miss greatly some of what you are enjoying.Still at much the same lattitude but at 6000' high we don't have the coconuts..) Cheers... 

Hello everyone, I have been growing my lettuce in my small backyard setup for 41 days now and my lettuce is still tiny. I thought I was supposed to have table ready lettuce in 40-50 days. Anyone have any idea why it's taking so long?

Christian, what are your nutrient levels? Light? temperature? are your plants showing any signs of distress such as yellowing? If you pick one up, does it have lng healthy roots? Impossible to even guess what's going on without more information!

Christian, do you have the system attached to a grow bed, or bio system of sorts for the Bacteria to colonize and convert the ammonia into usable form for the plants?

The small system that I'm using is the one shown on my avatar. Water temp is always between 70-84 degrees. They get around 12 hours of light. One small lettuce has one leaf starting to yellow a little bit. All the other lettuce looks nice and healthy, just very small for being 41 days old. I started them out in root cubes in a shallow pan with water for 22 hours a day and 2 hours of no water. Then when they had their first set of leaves, I put them in net cups (with the root cubes). And thats where I'm at now. They have 3-4 leaves each but are tiny. I also have 2 serrano pepper plants in there and they have stayed pretty small too. They have 4 leaves each but haven't grown from there.

How do you help with Blite on tomato plants so that you do not hurt the fish or kill bacteria? Thank you for your help.

Cristian, I would guess that your problem is that the plants aren't getting all the minerals/nutrition that they need. Check your PH regularly to see if it is stable and in the right range. If you show/send a picture then I can probably diagnose the problem.
Observation from picture:
If your system is small and exposed to rainwater then controlling the system is futile. 

Dustin, you might try regular spraying with Botanigard. It's expensive but safe to use right up to harvest, and controls a wide variety of pests. Many tomato wilts are carried by bugs, and the idea is to keep the bugs down, so stary spraying early (when plants are a foot high or even sooner). You can't kill the blight, the idea is to keep from getting it.

Christian, I agree that you probably have low nutrients in your system. How many fish do you have? How large are they? I recommend you get a nutrient test kit and check for pH, ammonia, nitrites, and nitrates. I like the liquid kits from Aquarium Pharmaceuticals better than the test strips. Again, a bit pricy, but easy and precise, and a $30 kit may last years.

We decided to try DWC for profit in a 1 1/2 acre agriculture lot that we have. We are building the greenhouse and putting in a 6000+ gallon tilapia grow out tank that will feed (2) 80'L x 16'W lettuce/produce troughs. Any tips or suggestions are greatly appreciated. 

*Also, if anyone knows where I can get a good deal on blue tilapia to properly stock my tank, please let me know. Looking for a good, cost-effective source.

Thanks

Christian, keep in mind that 16' wide troughs will make it difficult to access the rafts in the middle without shuffling things around. Friendly built 2 troughs that are 8' wide and do not like them because of the difficulty in working them.

Wide troughs are better for monocropping where you put seedlings in at one end and remove mature plants at the opposite end. All the plants in a wide trough need to grow at the same rate for it to work properly. If you added some plants with a shorter grow out you will be trying to fish them out of the middle of the big troughs.

The only cost effective fish supply at the scale you propose is to start your own hatchery. Tilapia bred very easily in warm water. The blue tilapia in my systems grow at about 1/2 the rate that me white hybrid tilapia.

Just talked to a new friend who has been doing aquaponics for a while. He suggests that I go down to 4' wide. I don't know how profitable that will be for me. I understand that the wider  the trough is, the harder it is to maintain the veggies in the middle but I also need to make money. Capital for this venture is high and I need to start producing large amounts right away to meet my local demand. 

Anyone know the price of the 4x8 polystyrene sheets. I heard those are the best sheets to use. Again, looking for something durable and cost effective. Just got a quote of $16.00 per sheet, maybe someone knows of where to get them at a better price.

As always, thanks to everyone for the help.

Well, you're ultimately limited by square area - not width. Almost every commercial grower uses more, narrower troughs.

Hey, 2" Dow blue board costs almost $50 a sheet here, what with shipping! $16 sounds great. It does need to be 2" thick, though, or it will break. You don't handle it much, but you do have to handle it some.

I've also seen a system that uses rigid plastic directly over "pontoons" made of PVC pipe. no foam. Seems to work and if you use a white plastic you don't have to paintit, as you do the blueboard.

As to speed, I suggest you build your system in modules - and start with 1 tank driving a few troughs. (I have a 1000 gallon tank running 2 40' troughs; i run low fish density because it's so much more stable.) Anyway, get ONE module up and running, and you will learn many, many things that will make it easier and faster to expand from there. I can pretty much guarantee you'll save yourself some painful and costly mistakes if you do this.

Kate, thanks for the tips. I appreciate things from a different point of view. I'm also looking for liners, if anyone knows of where to find them at a good price let me know. Thanks

Mahalo Giorgio, do you put anything inside of those pontoons? Such as foam material, like those kids pool float tubes etc.. or does the air inside of PVC remain sealed? Thanks

in reply to 

Aloha !

Here are a couple more pics to give you better idea.

The GM Raft System

This design is fricking awesome...I'm growing lettuce almost  2x faster than regular foam rafts and cause the only part of the raft that touches water is the 2" pontoon there is lots of aeration underneath the root system (WITHOUT) the need of air stones, valves, siphoning or any other device.

Is very simple concept that works great, I'm sure whoever tries it will love it and is less than 1/2 the cost of the foam rafts and  about 75% less work without the mess and once you get one going you can make a bunch at a time.

I used 3 screw at the ends and 4 on the sides, make sure to use stainless

Christian I'm currently constructing a system running 12 x 40' troughs to obtain a large volume you would probably want to go with a large number of troughs.

What spacing are you guys using for lets say specialty lettuce? and basil? I had my mind set on 28 lettuce per every 4x8 sheet and my buddy told me that I was under cutting it way too much. He suggested 48-56 per 4x8 sheet. Not sure how big the lettuce can grow in 2" net cups with 48 per sheet.

Hey Christian if you are looking for a great type of liner here is one spot to try, this is the same liner material that the Friendlys use in Hawaii and at Green Acres Organics use for all there troughs.

DuraSkrim 20

http://buyplasticnow.com/Products/String-Reinforced-Plastic/Dura-Sk...

I cut my 4 x 8 sheets of blue board into 4 2 x4 pieces.  This makes ror easy removal when needed. Each 4 ft x 2 ft section is  drilled for 33,  2 inch holes.  The holes are in 5 rows 3 rows of 7 holes with 2 rows of 6 holes off set in between the 7 hole rows. For a grand total of 132 plants per 4 x 8 grow trouth.  I plant only black seed leaf lettuce and no head lettuce.  For climbing plants I attach 1 inch by 2 inch  4 foot long to each side of the grow trough whicj I span with another 1 inch x 2in a little bit longer than 4 ft.  I the  hang a curtain of plastic "chicken wire" from this frame.  I try and keep all 33 plants all the same on one 4ft x 2ft section. This way I can have up to 4 different types of plants in one 4 x 8 grow trough.  

On blue board.  I recently purchased 12 sheets of 4ft x 8ft  2inch thick blue board from Gator Gypsum, in Largo, FL.  I am 45 minutes away so i picked them up in my Ford F150 pick up truck.  Price was $2.28 a sheet plus sales tax. My guess is they will ship it, if requested.

I am just starting using rafts. Was wondering how the roots

get oxygen if they are in the water all the time. Do you need to position the baskets so that some of the root system is out of the water to get oxygen?

Robert, to aerate your plant roots, part of your setup should be the inclusion of 1-1/2" by 0.75", 0.35 cfm airstones in your troughs. Dependent on the size of trough you're using. A 4'x8' trough would normally have one airstone which would be of course driven by an airpump. Thus your roots remain in the water. Hope this helps.

Christian, regarding the spacing, I've experimented a little with it and what I've done is have them really tightly spaced in the early stages of growth so I would have a 2'x4' raft with something like 50+ holes then I would move them to a raft with anywhere between 28 - 32 holes.

Then I would place them on one with less holes:

Dave thanks for your input brother. I tried looking up Gator Gypsum but their website is just a blank page. I'm going to call them in a few. How do you like their blue board? Do find it to be sturdy and possibly long lasting?

Nigel, thanks for the info and the pictures. Glad to know that someone else has done it and it's working.

Dave just got off the phone with Gator and their price per sheet is $41.28. How in the world did you get it for $2.28?

Dave, can you put up a number, email address or url for Gator? I keep finding one in Clearwater and I'm not sure if its the same company. I'm based in the Caribbean and that's the best price I've seen on the Blue board in a long time.

Hello Nigel & Christian,

I totally agree that $2.28 for a 4'x8' 2inch Dow Blue Board sheet is a "dream" price...I would like to buy a lot of them at that price. I believe that this was just a "typo" and the actual price is closer to $41.28.

Still, if I can buy them for $2.28 per sheet, please let me know ASAP :-)

God bless

Does anyone know where to get the blue board at a good price? Has anyone used any other kind of board?

I have some cut pieces (2x3) of blue boad in the Tampa area.

Hey Everyone,

I am searching for a Business Plan outline that I can follow to create my own business plan for an Aquaponics Farm. Does anyone have a business plant outline that they would be willing to share, or know where I can find a good outline? I would greatly appreciate it!  Thanks,

Jordan

Hi gang:  It has been a while.  I have been busy expanding my operation.  I have a question for all.....Has anyone tried their hand at growing grains??  My guess is rice might work well.  How practical, is a whole different subject.

Oh, and in reading the posts, seems like I made a major typo back in April on the price of DOW blue board.  Price I paid was $42.28 not $2.28.

Cereals, or grains, whatever you Meguren call it, don't tend to work well in hydroponics, but rice is the exceptional exception. Pseudo-grains, like Quinoa, have been known to do wonderfully in hydroponics (I don't feel like digging up the Gen Hydro blog post right now). So, try things like that. Also, in media based systems, corn has been known to do well.  

dave you can look at growing fodder on the web and get an idea of what might work

I just purchased 2" Blue scoreboard from Marjam for 36.12 per sheet.  Already scored for easy breaking into 16 or 24" rafts

*Meiguoren. Details, details. 

RE:Grains. I'm growing corn just to see what will happen.