DWC ... Floating Raft...

[Nathanael]

DWC... has anyone been successful with it in a smaller backyard system and is it worth the go? 

This monday I will be finishing my 2nd 3'x6'x16" gravel growbed and I'm trying to decide if its worth adding a small DWC to complete my system for the time being. 

The order for the DWC would be as follows: Pond - Swirl filter (completed) - Bio filter (completed) - Floating Raft - back to pond via overflow. 

DWC system would be about 100gls. 

Any thoughts about this? Is it worth the go? 

If so, what should I focus growing? We love fast varieties of lettuce, strawberries, spinach, chard. to name a few.

[Sam Burton]

I have a small DWC, but don't use a pond.  I've thought about one several times.  My raft system works great....Now.  I made two mistakes when I got started. The first time I planted it, I put in plants with higher nutrient requirements than the system would meet. Instant Fail. Then herbs and lettuces grew great. The other fail was trying to grow tomatoes without adding extra oxygen to the grow tank water. They grew well for a while, then died. Once I added some air stones, things got better. Remember, Oxygen is fundamental.

The system you've designed looks like it should work fine.

[Rob Nash]

Rafts are a great way to add to a system. You really won't need a swirl filter post gravel, theres just not that many solids left. You will want a pollisher(bucket full of orchard netting)It will keep your raft water nice and clear.

[Jon Parr]

I'm with Rob Nash on the polisher, or mineralization tank as some call it. If you add gammarus to your system, you may not need a swirl filter or biofilter. And on a small DWC like you're planning (at 1' deep that is less than 14 sq ft), I would recomend a supported board on top of the bed, as opposed to floating rafts, to allow air-flow to roots.

[Harold Sukhbir]

Hi Nathanael,

That crop selection will grow in DWC quite well. If you can keep the flowrate between 6-10 GPM supplemental aeration won't become necessary, however aquarium air pumps are not costly and use very little power, so, it will be a great idea,especially when you see the impressive growth! The more mechanical filtration the better. Design that allows solids to remain longer in the AP system give maximum mineralization, so that we optimize the use of AP nutrient rather than throwing it away.

[Nathanael]

Thanks so much for the good feed back. 

My plan is to include a small venturi going into the DWC to help with oxygenation.... how do you all feel about venturi's from in the inflow...

 @Rob Nash and @Jon Parr When you describe a Polisher, does this land right before the DWC? 

My plan is to go straight from Pond to the DWC and not through the growbeds. I didn't want to run the risk of any nutrient deficiency. Maybe that is being too paranoid and it would be best to go through one of the gravel beds first.

 Also, are gammarus available at any local aquarium shop or are they a special order type thing? Would they be placed directly into the DWC or the Polisher?

@Harold Sukhbir I took some looks at your system and saw that you are doing very similar to where I'd like my system to be soon with a mix. What are you doing to add mechanical filtration. Coming from your fish tank, what is the journey of water before it reaches your DWCs?

Thanks again for all the wisdom and help.

 

[Nathanael]

@Jon Parr I also had one more question. When you mentioned a board supported on top of the DWC how would you describe a good way of doing that? I've seen the new pontoon version.... Would using 1/2" plywood painted white do the trick? Then just lay it on top of my DWC frame?

How much space around the edge would I need to leave so that there is plenty of oxygenation under the plants. And also, do you all recommend 2" or 3" net pots.

[Rob Nash]

I just realized you were going straight to the raft.
I would recommend gravel first. If you only have room for one bed, then gravel is better than a raft. If you have the room, you could do a hybrid of the two and run the raft after the media bed and polisher.
If you would Like I can post a diagram that makes it easier to imagine.
The heater how to shows the thermostat that i recommend, you may need to find the second post for the submersible version i think... It has a link to the site.

[Nathanael]

Hey Rob, a diagram would be super helpful. I am adding a second growbed monday so I could easily set it up to drain into a  polisher and then into the DWC. I just want to make sure that the DWC is getting pure enough water so I'm not having to deal with suspended solids attaching to the roots and blocking oxygen. 

I am eager to learn what you suggest as a sufficient order of flow. 

Also, I did find the thermostate you recommended. Thanks a bunch. how often are you having to run your heater in your system?

[Harold Sukhbir]

Hi Nathanael,

From the FT system water enters a combination swirl filter/ net filter,positioned about six inches above the raft and flows by gravity to DWC. I have also fed raft from GB filtration but its not my first choice, as some sediment does get through to the plant roots(and this was with pea gravel GB's!) A lot has to do with a suitable flowrate as well. Swirl/net filters can also add biological filtration to AP systems depending on their design.

http://community.theaquaponicsource.com/group/raftdeepwatercultureg...

[Bob Vento]

Hello all,

I am looking to expand my current grow bed system and add a raft system. What would you suggest to use for the trough? I've seen 55 gallon drums cut in half, construction drainage pipes modified, wooden boxes with pool liners in them.

I am so confused as to the best method of a Raft/Deep Water Culture system. I would like to be frugal and cost effective but don't know where to start.

Also, if the water ... comes from the fish tank ... is run into a polisher and then out to the raft system ... and then back to the grow bed which would return the water to the fish tank ... and start the process over again. Would enough nutrients reach both the raft system and the grow bed system to sustain veggie growth. Any info or links to info would be very helpful.

Thanks,
Bob

[Nathanael]

Hey Bob, Lowe's sells a 53" kiddie pool that is 12" deep for $16 That might work really well for a DWC. It will at least give you a chance to get things setting up and running until you are able to purchase or build something that is more long term. 

They are UV resistant and made of a Polypropylene Foam. If you can get passed the little kiddie fish on the inside. lol

You wont see them anyway since your rafts will be covering it all up. 

Next, I would say Wood with pond liner. But i'm definitely not the expert. I'm just finishing up my first DWC so I'll post pics soon and let you know how it's working out. 

[Rob Nash]

Try a mortar tub. You really don't need that much raft to grow some lettuce for the family.
I really don't recommend rafts for small systems, as you can grow any thing you want in the media beds including lettuce, which all you will want to grow on the rafts...but a motor tub makes a great little raft.