Comment

Comment by Chris George on September 10, 2012 at 5:16pm

@Vlad...thanks, I thought it was Larry in CG....but I was headed out the door and didn't have time to check.  Great link, too, I'm reading it now.

Comment by Vlad Jovanovic on September 10, 2012 at 4:24pm

http://www.ctahr.hawaii.edu/hawaii/downloads/Three_Non-circulating_...

@Chris...I think it was Larry in Casa Grande (Arizona AP) who built such a PVC framework...

Comment by Chris George on September 10, 2012 at 4:06pm

@Joshua...one of the members of the Arizona group (where I'm at) designed a pvc framework in a growbed that extends down to the bottom of the tank....you might check out that board....I can't remember off the top of my head who it was, but someone will know, it's a friendly bunch!

Comment by Josh on September 10, 2012 at 3:50pm

Just had a though.  Tell me what you all think:  In my lastest design, my dwc is going to double as my sump in a pure flood and drain (no siphons, just gravity and a timer)  mixed media system  Therefore, the water levels in the sump/dwc will fluctuate when the pump is running (which is in the dwc/sump obviously).

My thought is this: In keeping with the idea of no added aeration, what if the entire  pvc board was supported with legs as a sort of growing "table" within the dwc?  This way, I could have the net pots/roots touching the water when the pump was off (say for 30mins or so depending on the on/off cycle) and then out of or nearly out of the water as the pump was on,lowering the water level. Wouldn't this allow for plenty of air/o2 exchange?

Comment by Josh on September 10, 2012 at 3:34pm

Thanks Arik!  So you are happy with the pvc board so far?

Also, one of the reasons Im interested in this method is for the OP's claim that the space between the boards and the water would make extra aeration unnecessary.  

Are you aerating?.

Comment by Chris George on September 10, 2012 at 3:16pm

@Arik...Great info, how are you thinking about attaching the soda bottles together?  I'm planning on something similar using Nalgene bottles (the ones from the hiking stores), not quite as big, but durable and they have a big, tight lid.

Comment by Arik Alan on September 10, 2012 at 3:13pm

I have built some of the "pontoon rafts".  Basically i have built all of them with overall dimension of 2'x4' in a similar construction method as described. I added more support and pontoons.  I have different size holes and patterns for varying crop/spacing.  My oberservation is: They are sturdy and easy to carry without worry of breakage so durability is good. I used 2" pvc for pontoons and ADDED and extra to the center. So 3 pontoons on each raft. It still sinks down to almost water level with plants/medium and definetly past netcups so you will need rockwool or hydroton with this use. soil is far to wet.  I HAVE NEVER USED THE FOAM RAFTS so i have nothing to compare to. I wanted to "do it once, and do it right" and it just seemed this would be a better method than fragil foam. it would seem to me to be better over duration of time but?????  feel free to pm for followup in the future. The next ones i will build will probably have a deviation from design to include spacer between pontoon and "frame" of raft. For the cost of larger pvc for pontoon use i would almost bet that empty recycled 2 liter soda bottles wood work much better, cost a fraction compared to say 3" and would have much better buoyancy due to considerably larger diameter. I'd like to have the netcup completely out of the water. I will be using 5 2 liter bottles for new design. one at each corner of frame with a single in the center.  hope this helps.

Comment by Josh on September 10, 2012 at 12:22pm

It shouldn't be to big a deal, but the extra space between the Dow board and the side of the dwc will allow for more light to enter. Thus more algae will grow and compete for nutrients with the plants you are growing. Shouldn't be much an issue but something to think about.

Comment by Pat Moore on September 9, 2012 at 7:47pm

I am in the designing phase for building two grow beds for a raft system.  The rafts need to be elevated about 3 ft off of the ground for accessibility.  I took the Friendly 3 day course and have their manual, but they only used ground mounted beds.  I would like to use 3/4" 4x8 ft plywood for the bottoms.  However, the Friendly beds were 51 inches wide so that they could fully use 48" Dow blue board with some room to spare for easy movement.  Does anyone see any issues with cutting down the blue board to approximately 46" other than some loss of area?  Also, instead of using a food grade liner I'm thinking of using glass cloth and epoxy for waterproofing the beds and would like to know if this is a good or bad idea.  I'm new to the forum, excited to be part of the community...

Comment by Josh on September 7, 2012 at 7:38pm

Hi all,

On pages 6 and 7 of the group's comment wall, a pontoon raft system is described by Giorgio.  Seemed like a good idea but I havent heard anything about it since it was originally posted.  Anyone tried this?

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