Odd question about DWC

Matthew Russell

Hey everyone, just joined the forum and thought I'd jump on the bandwagon. Kachok, why don't you either add a cheep air stone or Venturi to your DWC, this should solve the problem immediately. Plus save a whole lot of work.

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Porter

Hey Matthew, nice to meet you, welcome to the forum, mate word of advice, never mention venturi's, or the cool kids will run out from behind the anti-venturi shelter shed and will mess up your uniform and step on your sandwhiches for merely mentioning the word, because they dont want to you to know that in grown up land venturi's arn't considered to be an inefficent gimick.

Matthew Russell

Hahaha, thanks for the advice Porter! Nice to meet you too mate. I'll keep the 'V' word to a minimum

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MartinC

Hi Porter, I've seen numerous good discussions on this forum about venturis so I am not sure what you're referring to or if you're just kidding around.

Regards, Martin.

tom77

I don't have anything against Venturis (although I don't use them) but as the sole source of aeration I don't like them since they rely on the water pump alone and if that fails then you lose aeration and water turn over (in a one pump system) at the same time which could mean some dead fish quickly.. while if I have a separate air pump then a mechanical failure is unlikely to affect both water and air pump at the same time. Although this point is mute if you run more than one water pump to pump water.

dasboot

And if you gravity feed your DWC a venturi aint no good...

dasboot

Kachok wrote:

Right now I am comparing and contrasting the advantages/disadvantages of NFT vs DWC, NFT seems to have an advantage in oxygen seeing as the roots are not entirely submerged allowing them access to atmospheric oxygen not just devolved oxygen, thus plants like tomatoes can do well while in DWC they struggle (or so I have been told) but this advantage has nothing to do with the thin film of water only the gap between the net pot and the water, could suspending the "rafts" of a DWC system a few inches over the water provide the same advantage? The reason I ask is the downside of using NFT with large fruiting plants, the blockage that the aggressive roots can create, while the high volume of a DWC system would easily accommodate such root systems.
Looking at ways to grow tomatoes and peppers without having to pump huge volumes of water through raised ebb and flow beds.

The major problem in AP in a NFT system your filtration system has to be up to the task of removing solids,otherwise your first few root systems start that job for you with poor results,in a DWC if you have 10 to 12 inch depth there is plenty of space for the few solids that get through to settle out on the bottom of the tank,if they show on your roots you need better filtration,i have ran DWC tubes and just plain ol DWC so i have a comparison between the two,my latest system runs surface skimmers to feed the DWCs with a very small filter with good results in regards of solids in the bed..

MartinC

In NFT that channels have small volume and are in the sun, my understanding is that this can cause high temperatures around the roots of the plants. The DWC is a larger volume of which keeps the temp stable for the roots.

Regards, Martin.

jayendra

Good reading here - learning a bit about this DWC, who ever he his.

I've got a question also.

Can you add a siphon to the DWC? Even a 1/4 or 1/2 siphon - reason being it would ventilate my fish tank beneath.

MartinC

Generally people use a constant water level in a DWC. If you flood and drain then the raft rises and drops all the time. I think the roots would get damaged to be honest but I am not an expert.

jayendra

If the top was fixed?

Its for a small setup above the tank.

tom77

jayendra wrote:

If the top was fixed?

Its for a small setup above the tank.

Those tanks look like they have sloped sides anyhow so a raft probably wouldn't slide all the way down anyhow, which is a good thing.. if they were made the right size the raft could slide down a certain way before jamming preventing the roots from being left high and dry for too long

jayendra

hmm - didn't think of that.

I was thinking more that the raft would sit on those little edges and stay at a fixed height.
Then have the siphon holes up higher than the bottom (about half way up) so it wouldn't drain completely and keep the longest roots touching water.

Main reason would be to create a nice stream into the fish tank for aeration

Matthew Russell

I reckon that'd still work fine.

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MartinC

Hi Jay, after reading your latest comments I think it would work.
How long would the cycle take?

Regards, Martin.

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Odd question about DWC

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