by Liz
Long-term Watering
2:15 pm in Uncategorized by Liz
Hi All-
I have had a 3-column (self-built)v 3.0 window farm for about 2 months now. I’m in Brooklyn, and it’s in a very sunny/hot window. This is great for the plants, but, As soon as this heat wave hit, I have had to top-off the reservoirs daily, or every two days.
Now, I’m headed out of town for a couple of days – just long enough to worry about the reservoirs running out of water. Has anyone had success with a short term “vacation” method? Is there a way to reduce the water evaporating from the system at all?
Well, you could reduce the evaporation by completely sealing the farm in transparent plastic.
Then, sooner or later, the humidity in the air inside will reach saturation and won’t be able to absorb more moisture… Whether or not your plants will survive this, though, depends on what moisture level you end up with, and how hot it gets in there…
Another option is to attempt some sort of ‘top up’ system.
you could get hold of an old window-washer reservoir and pump, a ‘cabin light delay’(pen-sized metal tube with two wires, used to keep the cabin ligt on in the car for a few seconds after you close the door), a switch and some sort of float.
Connect the pump and switch to a 12V power(wall-wart or battery), place the float in the reservoir, and hook it up so that it activates the switch when it nears what you consider ‘low level’ in the reservoir. This will make the pump run for a second or three(enough to lift the float and release the switch)
Then connect the delay across the switch. There should be a connection-diagram in the package if you buy it from an accessory shop. This will keep the pump running for another few seconds…
Remember that some liquids will always drip back down from the farm after the airlift stops, so the lowest level measured during airlift operation isn’t the same as ‘airlift idle’, and that the ‘trickle’ together with the amount the pump adds to the reservoir must not be enough to overflow the reservoir…
(The pump will be activated while the airlift is operating, after all.)
I’ve been tinkering, on and of, with this system myself, but haven’t ttempted to run it yet. (I have a problem finding/making a float that can be inserted into my reservoirs as I have free-standing reservoirs with no cut-outs. With all the tubes and pipes going in and out, there’s very little room left in the neck)
My solution for the summer vacation(coming up in a weeks time) is to run down the farm. I’m down to two columns(down from 4), and just a few bell-pepper plants left. The good part of this is that I can thoroughly clean the parts that I take out of use…
A third solution is to split the columns…
You’ll need to get hold of more equipments(pumps, vlves, needles, tubing and so on) but it’ll allow your farm to work for longer.
And then there’s the fourth solution… Largr reservoirs…
(I use 4L bottles… With two 4bottle columns on each they give me two or three days unroubled running before requiring a refill, uless it’s extremely hot)
I’ve been wondering how to do this too. This video could provide a way to link reservoirs that would act as one big reservoir: http://www.youtube.com/watch?v=x8kJ3l4yPLU. That’s been my thinking so far.
The ‘large reservoir & siphons’ could work, but…
Take a measurement of how much liquid you use each day.
Then mark the ‘max fill’ level of the reservoir, and also the ‘low’ level.
That is the max variation liquid that can happen to your large reservoir.
I use about .5L on each reservoir each day(for a total of 1L) and the max variation I’m comfortable with, is 8cm (a little over 3″)
For me to be gone 3 weeks(I will be gone for that long, actually), my reservoir would need to hold 21L+ of liquids.
21L = 21000ml, also known as cubic cm(1L = 10x10x10cm cube)
21000 / 8cm = 2625 square cm surface area of the reservoir.
That would be a square container 50×52.5cm (about 20 x 21″)
Or about 57cm(23″) circular container.
This doesn’t take into account evaporation from the large reservoir, which by necessity has a large surface area.(some of it can be avoided by adding a lid, but as it can’t be airtight, you will lose some.)
A lot of factors will influence the evaporation.
Is it a viable system?
For a few days, yes. For longer periods, not really.
Just make absolutely certain tht no bubbles can escape the airlift and enter the siphon as that will stop it functioning almost immediately.
Hi Liz you could take a look at this link. It seems like a simple and cheap solution to your problem. http://www.ultimatereef.net/forums/showthread.php?t=254985
When I have to travel, I just submerge my bottom reservoirs in a small aquarium or tupperware bucket that is at least as deep as the whole bottom bottle and its air injection mechanism.
It’s the same technique we recommend for folks who are doing aquaponics. Basically, your windowfarm is just pulling from a larger body of water but can still use the same low power airpump equipment and head height factors. As long as the bottom bottle’s refill hole is below the surface of the water it will draw in water from the larger reservoir. Kinda depends on your sill height and depth.
The other option is to just do something like our school kits. This was one of the many factors that led to our creating a different design for schools– lots of two week breaks. See the parts here: http://www.windowfarms.org/images/store/C-kit.jpg. We use a T-valve configuration with a larger single reservoir. Its not as pretty and takes up more window space but neither of those is a big concern for schools.