The transfer of oxygen from the air to the water through passive means does not deliver enough O2 to the plants. So even though they have all the water in the world, they are sufficating. It’s like a person going all day without drinking any water. They drank tea, coffee, soda, juice, etc, but no water. You’re dehydrating yourself and don’t even know it.

The air-lift method allows you to use the same water supply, only topping it off when necessary. If there were no pump, you would have to use a fresh supply everytime to enusure everyone is getting their fare share of O2.

Anybody have any suggestions for how we can O2-ify our gardens using less energy?

What Dean did/does on Urban Green Survival, with his no pump system, is change the water/nutrient mix after cycling it through his set up 3 times.

Reposting his link:

http://urbangreensurvival.blogspot.com/2010/07/hydroponic-bottle-garden.html

So, here we go:

The pump will need a proper cover against the sunlight, but I haven’t figured out an elegant way to make one yet. If only I had black aluminium foil lying around …

The mini cucumber has decided to rear its head, after careful deliberation.

wild tomatoes

The yellow wild tomato is well ahead of her red cousin in the background, but for a week I think the height they’ve reached without artificial lighting and in a window facing east is acceptable.

butterwort

And to finish off, my watchdog. No real dog – I leave that to Lorne – but a butterwort, charged with devouring fungus gnats, mosquitoes et al.

Cheers for now.

Your reservoir system is a liquid circuit controlled by a pump on a timer. The pump needs to only pump water, not air. Running a water pump dry will kill it. The relationship between the amount of time your pump is turned on by the timer and the gallons per minute flow of your pump dictates a minimum amount of water in your system and, therefore, a minimum size for a sewer pipe reservoir.

However, there is plenty to tinker with here.

Here are notes from my thinking when I wrote that part of the Reservoir system How-to. They are notes that I have not really edited, so ask questions if something is unclear,

Theoretically, let’s say our pump pumps 500gph. That’s about 8.3 gallons per minute. We have decided that we lose about 25% to the curve at the top of the reservoir, and we probably lose about 10% to any remainder at the bottom that is too low for the pump intake. That means that when the bottom reservoir is as full as it can be, only 65% of the water in the tube can actually cycle through the system. So, 65% has to be at least = 8.3 gallons, which means the total pipe capacity if completely full has to be 12.8 gallons.

The pipe formula is

length of pipe = volume in gallons/0.00432900433 x Pi x radiussquared

so when the radius is 4” for the sewer pipe with 1/8” thick walls, the minimum pipe length formula is

GPM/0.21759949= min pipe length

For this 500 GPH pump, minimum pipe length for a one-minute pump-on cycle with the timer we have recommended is

8.3/(0.00432900433 x 3.14159265 x 16)=

8.3/0.21759949

= 38.14”

and if you want it to rest inside the window sill, that has to have the pump length added to it, which puts us at more like 40”

A typical window is 36” wide. So:

1- Maybe we don’t need this fancy a pump because we are only pumping up about 4+- feet of head. Maybe we could find one that would fit inside the reservoir so we don’t have to suspend it outside.

2- If we still want to use this pump, we should have people make them wider than their windows and suspend them outside the windowframe.

3- ??

RESEARCH—

Ecoplus pumps correlated with head and cost are here: http://homeharvest.com/hydroponicpumpssubmersible.htm

(CAUTION: BE of these pumps- several of the ones we ordered did not pump as high as they were rated to pump!! Go a size bigger if you’ve got a tall window and can mount it outside the windowframe!)

Ecoplus 633 – 7.87 feet of head- pumps 633 gph

Gpm=10.55

Absolute Minimum pipe length with our timer is 48.5” +pump, assuming it drains completely within 3 hours

Drip rate needs to be 3.5 gph

½ inch and ¾ inch hose connectors

7.2 inches long (with cover that we remove) by 3.1 inches wide by 4.3 inches tall-

won’t fit in pipe

$46.95 at home harvest

Ecoplus 264- 6.39 feet of head- pumps 264 gph

Gpm= 4.4

Absolute Minimum pipe length with our timer is 20.22”+pump, assuming it drains completely within 3 hours

Drip rate needs to be 1.5 gph

½ inch and ¾ inch hose connectors

6.2 inches long by 2.5 inches wide by 3.5 inches tall-

will fit in pipe $21.95 at home harvest

If you put the Ecoplus 264 pump timer on a two minute duration cycle, you’d pump 8.8 gallons and your pipe would have to be 40.44”+pump long.