Backyard Aquaponics
A place to discuss aquaponics

From reading here it seems to me that the ongoing power usage of pumping the water can be used as an argument against AP due to the direct energy cost of keeping a system going.

One idea I have to circumvent the need to raise large volumes of water is to "dip" the growbeds. If you arranged two similarly weighted grow beds (with light media) to counterbalance each other then you could make a kind of see-saw that lowered one while raising the other. If you had flexible pipes with one end in the bottom of the fish tank, through the tank wall and into the GB, as it lowered below the FT water line the water would siphon in and then out again as you raised it up. The counterbalanced tank would mean that the energy used to move them shouldn't be too large if you keep friction to a minimum. Some kind of geared down motor with a crankshaft might work for the moving. This might be more energy efficient than pumping water up and then losing all the energy as it flows back down.

Obviously, large grow beds would mean that this system would need to be able to handle the weight of the GB with water and media, which might mean it is not really feasible. Anyone considered this, or even tried something on a small scale?

The weight would be enormous, thus the mechanism would need to be very strong and expensive. On the other hand, what you are looking for here is a far more efficient pump. Go ahead and do a quick search: we've had some long and heated conversations about pump efficiency here.

Oh, and welcome!

welcome indeed

nice to have a friend at arms

your idea is a variant on the one I posted here:
http://backyardaquaponics.com/forum/vie ... cket+pump+
where I describe a bucket pump based on the same principle

the advantage of your system is that less water needs to be moved

your idea can be simplified by hanging the growbeds straight over the fish tank or over a long shallow race: no hoses needed
having a series of small growbeds would make the flipping of each seesaw lighter
but the construction would need to be just as strong
connecting two seesaws that counteract would put less strain on the construction by keeping it always balanced
which would mean that the flipping of the seesaws would need very little energy

... the longer I study it, the more I like your suggestion
as it allows for absolute minimal "pumping" where the growbeds are concerned

with the right water absorbing media the frequency could be even more diminished
having a rest position with the seesaws balanced horizontally in the middle, both suspended above water level, would allow for two short "dips" followed by two long drains

but I see some problems:
a minor one: keeping the growbeds balanced as the plants grow
this could be solved by growing the same vegetables in each balanced couple of beds

and three major ones: biofiltration, removal of solids and aeration of the fish water.

these stay a challenge
well worth trying to solve
won't be easy

but let's ride the new tide:


frank

They say the same thing about my computer, TV and fridge. But I need the beer and the TV. The pc is good also. Any system is going to need energy. The form it comes in differs from electricity to some guy with a bucket. All we can do at the end of the day is try to minimize that energy or counter balance it. Like the savings from the plants and fish that goes against the energy that is used.

Welcome to the madness.

hygicell wrote:

Balancing could be hard, but you could add and subtract weights each week to keep it close to even.
Biofiltration and removal of solids might work if you had the grow beds outside the FT with a pipe going from the bottom of the FT, through the FT side so that it siphoned when the bed was lowered below the FT water level.
Not much suction though I guess, so that might not work. I did say that this is a half baked idea. Oh, and vines would be right out!

You would need an air pump for aeration, but that should use a lot less energy than pumping water.

Dufflight wrote:

Thats what I was thinking in this gedankenexperiment - minimise the energy required for the water movement. I guess having your GB only just above the FT water level would probably work just as well without the hassle of trying to set up the "dipper".

Thanks for replying though fellas.

You are still going to have a huge amount of work in lifting the waterlogged bed out of the water, and dipping the other one:
If the two beds are perfectly balanced, you provide a small amount of energy, and it starts one of the beds dipping. Once the bed is dipped, when you attempt to pull it out of the tank, and dip the other one, you are going to be attempting to lift a GB full of water - although it will be counterbalanced by the growbed that is about to be dipped.

Example - 100KG beds that hold 50L of water when full.

Left bed right bed status
100KG 100KG both beds balanced above the tank. it takes little energy to start the dipping.
150KG 100KG left bed submerged start trying to dip the right bed
120KG 150KG Right bed dipped, left bed dripping. Now pull the right bed out...
110KG 150KG both beds suspended, right bed dripping...

Actually, as you started trying to dip the bed, the one pulling out of the water would slowly drain, so it wouldn't really be the full 150KG, but it would be significantly heavier than the one that is high and dry.

The simplest way I could see to lift the bed on the see-saw would be to pump water to the upper bed. But in that case, why bother with the see-saw?

-Doug

The simple version of this idea is the manual bucket lift hydroponic flood and drain set up. Basically, the nutrient is in a bucket that has a hose attached at it's bottom and the grow bed has the other end of that hose attached at it's bottom. When you want to flood the grow bed, you lift the bucket of nutrient up above the grow bed and the bucket drains into the grow bed. When you are ready to drain the grow bed, you put the bucket back on the ground below the grow bed and the nutrient drains back into the bucket.

That above idea only really works for rather small set ups and doesn't really apply well to Aquaponics since any fish in the bucket would be rather stressed out flopping around in a drained bucket.

I'm not sure if you would get enough filtration on a system with much fish load simply by dipping the grow beds. I fear some form of pumping will probably be required though I have put forward that this pumping could be done manually at intervals.

Think about ways to lift a large tank of water high enough so that it can drain into the fish tank or grow bed over a period of time and when emptied the counterbalance could be hoisted back up and then allowed to lift the tank back up again.

I don't think I would want to be moving/lifting a growbed full of plants, especially large stuff needing training like tomatoes, beans or peas. Moving the water container seems far easier to me.

I've always like the idea of the GB's on a large cylinder water wheel. A small water pump sprays water into the first bucket and as it fills the wheel turns. Still requires power but the size of the wheel and the amount of GB would be pretty large. Originally thought of it when I saw one of those omega gardens. And that a small water pump would be better than a geared motor turning the cylinder because it would mix the water and add a little o2 while it was at it.

good thinking, Doug,
there will indeed be a difference between a soaked and a drained growbed
but far less than what you suggest:
when I see my siphons kick in, I see a lot of water coming out
and it comes out fast ! even if constricted by a 25 mm pipe
I have not measured, but I would guess 80 to 90%
so only 10 to 20% of the 50% of the water volume remains
so only 5 to 10% of the growbed volume remains

depending on the media used, the percentage difference in weight of both growbeds would be mostly even far less than that
wet gravel weighs twice as much as water,
http://www.simetric.co.uk/si_materials.htm
so with gravel only 2.5 to 5% weight difference would have to be tilted
(still guessing, should be measured)

if, like I suggested, two counteracting seesaws could be interconnected, there would be no difference at all

haven't figured out whether that would be technically feasible though

frank

Float the GB on a centered round pontoon ie big pipe ends sealed then see saw it

excellent idea, Sleepe

frank

If the pontoon was divided into two chambers. You pump air into one and it float out of the water while the other side goes under. Then you swap and the air goes out of the first putting a little o2 into the water as it empties and the other side fills and floats.

No matter what scenario one comes up with, one will still need to lift the weight of the water, plus any container etc. Simplest solution I can think of is modifying TCL's FT idea with a liftable sump on flex line. You could have simple valves (soft rubber flappers) so when low it fills from the growbed, when high it drains to the FT. CHIFT variation. Biggest issue I can see is lifting it efficiently.

thanks for the tip, Sleepe:

after the salad seesaws

I proudly present:

the salad merry-go-round:


should need very little energy to turn as it is as good as completely balanced
and provide good aeration by both the dipping and the dripping of the draining baskets

shoot your remarks

frank