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 Post subject: To air gap or not
PostPosted: May 12th, '15, 03:07 
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Setting up my larger system with some floating beds and I just cannot decide through all my research if I should leave an air gap or not? Thoughts and pictures please of how you did your system! Thanks

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 Post subject: Re: To air gap or not
PostPosted: May 12th, '15, 05:00 
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I wondered this at first too but apparently the air gap idea was mainly for hydroponic grow beds. It could be applied to an AP system but from what I've read it's just easier to have an air stone in your DWC. If you're trying to keep the energy costs down the air gap might be something to experiment with but there are some potential issues with it. When a raft sits on the water it provides some biofiltration surface area. You might also have some nutrient deficiencies that lead to smaller roots on certain plant varieties. Which makes it hard to adjust the water level to a one size fits all.


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 Post subject: Re: To air gap or not
PostPosted: May 12th, '15, 05:33 
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Tests have shown that leaving an air gap is beneficial to plant/root growth. Achieved by raft design or spacing the net cup leaves the raft touching the surface of the water to allow surface area for bacteria colonisation.

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 Post subject: Re: To air gap or not
PostPosted: May 12th, '15, 10:01 
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Ah, you're right I'd forgotten about the spacer alternative. So it's just the net cups that are elevated. Which leaves a small void.

I'm still curious about the subject. Is this the personal experience of someone here or is it documented somewhere? Just wondering because when I asked about it no one seemed to have tried it.


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 Post subject: Re: To air gap or not
PostPosted: May 12th, '15, 10:26 
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i posted this the other day and i can’t remember where so here it is again,Zweibel this is how i configure my floats,they are 2 inch poly with the large pocket sunk to half way.The seedlings are started in a float with no spacer so as the net pot just touches the water,then as they get established they are moved into these.My notes say they are growing quicker in these floats,i add a lot of air into each DWC,i feel these pockets help utilise this even more.


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 Post subject: Re: To air gap or not
PostPosted: May 12th, '15, 11:24 
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Nice pics. :) I think you actually posted some in a thread of mine a while back. I'm losing it. I didn't realize you had done a comparison on the growth rates. Cool :)


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 Post subject: Re: To air gap or not
PostPosted: May 12th, '15, 11:51 
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What i need to do now is have two floats one with pockets one without and compare the difference as its all to easy to convince oneself that things are an improvement,but with a visual comparrison you can’t kid yourself.

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 Post subject: Re: To air gap or not
PostPosted: May 12th, '15, 20:54 
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Good info yet now I have more questions. My system is in an outdoor greenhouse and I am trying to decide what foam to go with. My first thought was the high dollar 2 inch closed cell that has the reflective surface to aid in heating the greenhouse. Is that to much heat to close to the plants?

I really like the tunneling idea you have done it gives you the best of both worlds.

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 Post subject: Re: To air gap or not
PostPosted: May 12th, '15, 21:38 
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High density foam is a good choice,as for the reflective surface i used silver Mylar,the type the use in indoor grow rooms to insulate my NFT tubes and i had no trouble,your plants will cover this surface very quickly especially lettuce crops negating its reflective properties,it will make it easier to clean though,young plants might suffer from the reflected heat.


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 Post subject: Re: To air gap or not
PostPosted: May 17th, '15, 18:44 
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Hi, I have recently set up my DWC using coreflute, Growgrips & an air gap. I used 20mm pipe to raise the coreflute & create the gap. When the seedlings are small, I can remove the pipes & let the coreflute float in the raft until the roots are long enough to be raised & still reach the water. I do have some deficiencies & growth was slower in the DWC than the GBs, but that could be due to it being a new system & it may have been over-planted - I have never registered any nitrates.

Here are a few pics to give you an idea what I did.

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 Post subject: Re: To air gap or not
PostPosted: May 18th, '15, 03:53 
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Not sure how that coreflute will work out. Mainly because I think you might get too much light passing through so algae could be an issue. I know a couple of other people have used it but don't remember the thickness or whether they were indoors or out (which could make a huge difference in light intensity). On the other hand, if it works, it's reasonably priced and easy to work with.


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 Post subject: Re: To air gap or not
PostPosted: May 18th, '15, 05:13 
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Scotty,Charlie used coreflute in his DWC i am sure he will give us the heads up on how it worked.

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 Post subject: Re: To air gap or not
PostPosted: May 18th, '15, 05:18 
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I like the idea of the corflute.... and a simple spray with chrome like paint, could solve the light. Transmission..

I would be interested to see how SAG affects both the tubes and the corflute, with more substantial plants like large lettuce ....


I have led a sheltered life... what are those foam crossie things holding the plant..??
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 Post subject: Re: To air gap or not
PostPosted: May 18th, '15, 05:24 
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I can see one of the problems with corflute is its weakness along the length of the hole through the middle,with mature plants in it it would want to fold along this,i wonder if you added two pieces together with the holes at 90 to each other would give the extra support,it would also help with the light transmission through it..... :think:

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 Post subject: Re: To air gap or not
PostPosted: May 18th, '15, 06:09 
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I would have to think how to cut neat holes.. I have never tried a conventional hole saw .. just concerned it would be rough..
And indeed, Contra lamination would give greater strength...

I could only see it working in a supported manner.. as it really does not readily float, with significant water getting into the holes ..
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