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Comparison of water usage in member AP systems
http://byap.backyardmagazines.com/forum/viewtopic.php?f=1&t=1438		 Page 1 of 4
Author:  RupertofOZ [ Apr 8th, '07, 19:24 ]
Post subject:  Comparison of water usage in member AP systems
Been some recent discussion regarding water usage in AP systems...

Some recent system designs and implementations appear to use quiet large volumes of water through the system/plant growth phases.

It was suggested in one thread that due to the area of flood and drain growbeds, combined with plant uptake ands transpiration, that water usage might be the equivalent or greater than some other discussed "open loop" systems and/or soil gardens.

Anyone want to fess up to what their actual usage per week/month might be in top ups and for any other reasons....

Maybe AP isn't as water efficient as we may think????....
Author:  veggie boy [ Apr 8th, '07, 19:28 ]
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I'm going through about 200 litres a week for my 1 grow-bed which is about 2 square metres. It has quite a lot in it so most water is probably going through transpiration. The bed is also in full sun - which doesn't help.
Author:  monya [ Apr 8th, '07, 19:29 ]
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I use about that for my system in the greenhouse I reckon. But I have never officially calculated it. Very rarely do I have to top the tank up.
Author:  RupertofOZ [ Apr 8th, '07, 19:29 ]
Post subject: 
Perhaps we should add tank size into the equation as weel so as to be able to compare percentages
Author:  monya [ Apr 8th, '07, 19:29 ]
Post subject: 
3500 litres
Author:  veggie boy [ Apr 8th, '07, 19:30 ]
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I don't think tank size has anything to do with it unless the tank is sitting outside uncoverred. What is of main interest I think is surface area of grow-beds and the amount of plant matter.
Author:  veggie boy [ Apr 8th, '07, 19:31 ]
Post subject: 
BTW - my tank is a bit over 1000 litres and my sump is another 350 or so.
Author:  Food&Fish [ Apr 8th, '07, 19:38 ]
Post subject:  Re: Comparison of water usage in member AP systems
I have 3000 litres fish water and 3 gravel filled grow beds 1000 litre total one strawbery tower and one aqua lemon tree4 nft chanels each 2.5 meters long
if i dont use the fish water for nothing else i use 50 litres a week average most times i use fish water to water the dirt garden glasshouse and 20 orchids under the gum tree every second day 300 litres a week
Author:  veggie boy [ Apr 8th, '07, 19:40 ]
Post subject: 
That's interesting F&F. I expect that other than the heat difference, the reason I am using more water is that my system is continually flooding then draining and the top of the gravel in parts is always moist, resulting in evaporation. I should look to fix taht and see what difference it makes. To what level below the surface do your beds flood F&F?
Author:  Food&Fish [ Apr 8th, '07, 19:43 ]
Post subject: 
veggie boy wrote:
That's interesting F&F. I expect that other than the heat difference, the reason I am using more water is that my system is continually flooding then draining and the top of the gravel in parts is always moist, resulting in evaporation. I should look to fix taht and see what difference it makes. To what level below the surface do your beds flood F&F?

about 2 in under the surface and thats for 3 min in the hour
Author:  veggie boy [ Apr 8th, '07, 19:45 ]
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Cool. Must drop my level. Easy to do by cutting a bit of length off the autosiphon. Main reason I have left it high at this point is that it makes it easier to germinate seeds. The answer would probably be to have a second autosipon bell that I chuck on when sprouting, then through the shorter one on the rest of the time.
Author:  Food&Fish [ Apr 8th, '07, 19:48 ]
Post subject: 
veggie boy wrote:
Cool. Must drop my level. Easy to do by cutting a bit of length off the autosiphon. Main reason I have left it high at this point is that it makes it easier to germinate seeds. The answer would probably be to have a second autosipon bell that I chuck on when sprouting, then through the shorter one on the rest of the time.

that will do it the surfice of my beds is never wet i always use seed bed raised seed just joined diggers today
Author:  Food&Fish [ Apr 8th, '07, 19:52 ]
Post subject:  Re: Comparison of water usage in member AP systems
seeing mine is flood and drain i have different stand pipes like joels i also have different size pipes for the nft deep water to start then bottom flood when established
Author:  veggie boy [ Apr 8th, '07, 19:52 ]
Post subject: 
Yep - I gotta start raising more of my own seedlings outside of the AP bed. Once I get my greenhouse for the AP - I will have a dedicated shelf in it for doing this and will seup a hose off the pump for me to water the seed trays when I need to - make it really convenient and easy.

Seed is so cheap when you consider just how many there are in packets.
Author:  Gary Donaldson [ Apr 8th, '07, 19:58 ]
Post subject:  Re: Comparison of water usage in member AP systems
Hi,

Quote:
I'm going through about 200 litres a week for my 1 grow-bed which is about 2 square metres. It has quite a lot in it so most water is probably going through transpiration. The bed is also in full sun - which doesn't help.


VB.....I'd suggest that a chunk of it could be going in evaporation.....particularly if the gravel is warm.

I can give you fairly accurate figures for water usage because I run a Daily Log for my system, however, water usage figures without vegetable production figures is pretty much a waste of time......and we don't normally keep vegetable production figures.

I doubt if AP systems would use anything like the amount of water that a soil-based garden does. Before we moved to water restrictions, we had raised bed sheet mulch gardens and, as water-efficient as they were, they would have used more water than our AP system does even when it is producing relatively heavily.

During the past couple of weeks, the mites/aphids have eaten more of our vegetable production than we have......and we've upset the satellite pots by pouring sediment into them......so that's about all I can contribute at this point.

This discussion has pointed to the need for us to keep better records around water use and plant production.

Gary
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