Backyard Aquaponics
A place to discuss aquaponics

I'm trying to come up with a good way to run Deep Water Culture (DWC). I'm planning on using Extruded Polystyrene (the Owens Corning pink stuff) as the raft (or pseudo raft). Running air out to the DWC beds is something I'd like to avoid if I can - Has anyone tried DWC without added air, just with flowing water and the rafts suspended over the water with an air gap - does it work?

Second question - will 2" net pots be adequate for bigger plants like tomatoes? I'd like to standardize on these because of less media being required, if they will work.

Finally - I was thinking of using 1 1/2 inch thick as opposed to 2" thick styrofoam. Anyone see any problems looming if I do this? If I have to switch from suspended to floating the rafts, would this thinner 1 1/2 inch raft still work ok? The price difference is a little over $10 a 4 x 8 sheet so I'm trying to save a bit.

Thanks

It works without the air, just supposed to be slower growth. Check out the DWC and aeration thread, I've been doing an experiment with and without air, and they are pretty close, granted the one with air went for 2 weeks without me noticing it wasn't running, so I'm not sure if that stuffed up the results.



They don't use air stones at all. I think they'd use some sort of injected oxygen to saturate the water with oxygen, but it does work without them.

The thing with the raft size, is the weight it'll be holding. Mine is 45mm (1.7 inch) deep, and if I had the raft full of something like celery, it'd weigh it down. If it's tomatoes, it's hardly noticable because they are tied up from above.

And with the pots, I've got 50mm net pots. The first lot I bought only had very little holes in the bottom, and it seemed to strangle the roots, they'd swell up on either side of the hole. With the net pots I bought, it has long slots down either side, and I haven't had this problem.

Thanks for the information. Do you have a picture of your net pots? The ones here locally look like this - http://www.htgsupply.com/files/admin/img/Containers/NetPots/2_inch_Net_Pot_Measurements.jpg
The slots seem a bit narrow to me.

I've also been considering an injector for aeration (like the spa jets for the RAS) or using some sort of delivery to buckets growing plants over the top of the DWC. These would splash water down into the system between rafts.

Any references for raft hole spacing you can point me to? I've probably found enough information on this but mostly geared toward lettuce so I'm looking for peppers, basil and things like that.

Scotty, check eBay or Amazon for LP50 lettuce cups.

Yours are extrememly similar to mine. The plastic walls are pretty flimsy, so the roots push them aside with ease, and break them with the stronger plants. My celery has demolished it's case, and wedged itself inbetween the foam. It's not going anywhere in a hurry.

I had lots of trouble finding the spacing for the rafts as well, I stuck with 30cm between each pot. Perfect for lettuce, and tomatoes seem alright with it as well.

I'd love to see what you come up with for the Spa jets!

+1 on what Charlie said. The website you linked is horribly expensive. Cheapest I could find was $50 for 1000 pots.

Charlie, I get zip when I search for LP50 lettuce cups, can you point me?

Edit: Found a picture on your system thread so I know what to look for, no need to post back Charlie, Thanks.

Collum - I'd probably just do the same spa jets I've been using for the RAS. Check my thread over there and you'll find a couple of pics. At most two jets per trough (they're about $25 each so it adds up fast). Wanting to run the DWC this way is one reason I'm setting up the grow bed in parallel with the DWC and not in series (this may come back to cause me problems later). I'm also considering running the pump on a timer so it would be intermittent. Thanks for the spacing info.

Thankfully I'm not buying them from the website - I just linked to show what the pots looked like.

Forgot to mention, the 2" net pots are 20 Cents locally.

Edit - Thought of another question. Do you guys use the net pot hole covers to keep out sunlight when the holes aren't in use?

I don't cover the unused holes. I haven't noticed any algae problems.

Byron could you post the link to that video? Can't see it or click on the link to copy to youtube

This is his youtube page:
https://www.youtube.com/channel/UC0g02K ... C2HXLT937g

He's put up lots of videos, it's from a large Aquaponics farm.

This is the video.
https://www.youtube.com/watch?v=nR5l2YowBuc

Cool thanks!

Hey Scotty:
I think if the plants seem to not be vigorous enough then you would want to add air. If you have excess water flow you could aerate using venturis or bakki showers or something like that instead of an air pump. The linear piston pumps are not expensive anymore on Amazon, about the same as an aquarium pump fro the pet store. http://www.amazon.com/Hydrofarm-AAPA45L ... iston+pump It seems like Ryan is able to grow large plants with small holes so I think as long as the stem of the plant fits then a 2" hole would be OK. Regarding net pots and media you might look into plugs (not sure how that works) or Grow Grips as an alternative. I used blue board which was not even 1" and the net pots were too wet, floating them higher would be better, just touching the bottom of the net pot.

Not trying to hijack this post, but Dave, do you think that amazon pump would provide enough air for a 20' x 4' channel, plus fish tank or should I go with a blower?

20 watt pump, no. I guess this is where things get expensive with DWC.

Didn't think so. Thanks!!