Wicking Bed Extension to an Aquaponics System?

jwnova99

I'm looking to install a spring to fall extension outside my greenhouse so I can run more fish during the warmer months. My tanks will support a lot more fish, but I need more cleansing media. I have a sloping hillside to the west of my greenhouse so I can easily pump water up the hill and let it flow back down to the fish tanks.

I could dig 16" deep trenches across the hill side, 5 to 10 trenches in all, line the trenches with 6" of pea gravel and drain pipe, and put 10" of straw, peat, coco, top soil on top of the pea gravel. I can design the trenches so that the pea gravel and pipe would remain flooded. I would use a timer to cycle the water through the gravel once an hour. All the pea gravel would act as media, and the nutrient rich water will wick up to the plants. Every hour the pump will exchange the water in the pea gravel.

I could then grow bushy type of plants that are water intensive like blue berries.

Problems I see is rain flooding the soil and leaching into the system, roots clogging the drain pipe over time, and dead spots.

A more expensive solution would be to half bury IBCs or barrels all over the hill side. I can just see the view from the road below...

. What every design I use has to remain flooded as to flood and drain that much media would fluctuate my sump too much.

Thank you for your input.

Colum Black-Byron

If you're replacing the water in the wicking bed once every hour, you'll still get the leeching from the soil you use. But that can be fine if you use the right type of media, something without fertilisers.

Have a google for Earthen beds, I think that's what you want.

However, a far simplier idea, just have a float valve connected to the wicking bed, and connect that valve to your pressure or return pipe, have it topped up with the AP water alone.

The good thing I see about wicking beds, they'll still keep the plants moist, so blueberries will be happy, but you can use things like sprays that'll kill off the fish. And it's wicking it up, so it doesn't really matter if the water below gets a little nasty.

jwnova99

Colum, Thank you for your insight. I was hoping to cycle the water so that the rock media would add to the nitrification cycle of the water allowing me to raise more fish in my tanks. If you have a rock bed with a 6" drain pipe in it, would the ammonia and nitrates equal out between the rock and pipe each time you pause the water flow?

Colum Black-Byron

I'd think a big pipe would help the water channel in it, water will take the part of least resistance, so it wouldn't be as effective with nitrification.

Actually, I just googled earthen bed, and I couldn't find much.

As far as I can tell, it's a constant flood media bed, half filled, then a fabric of some kind to act as a soil blocker, and soil is placed over the top. So the water will run through the beds, it'll wick up. Just make sure the water level in the bed isn't too high, or you'll end up with problems.

Have you thought about just putting long rows of constant flood beds in? And just turning them off when it gets too cold? You'll need to watch you're stocking rates that way though.

Food&Fish

A bit of a read but from page 145 in you may pick up a few tips
viewtopic.php?f=18&t=663&start=2160
Ps check the end of the thread for latest photos

jwnova99

Colum Black-Byron wrote:

Have you thought about just putting long rows of constant flood beds in? And just turning them off when it gets too cold? You'll need to watch you're stocking rates that way though.

Colum, I've thought about that route, it would be more expensive. I think in time, I'll start lining up IBCs, and when I have enough of them in long rows down my hillside, I'll build a solar frame over them. Before you know it, I"ll have a 2nd GH.

.

jwnova99

Food&Fish wrote:

A bit of a read but from page 145 in you may pick up a few tips
viewtopic.php?f=18&t=663&start=2160
Ps check the end of the thread for latest photos

Thank you F&F. I have one wicking bed, but it isn't piped into my aquaponics system.

boss

Quote:

I could then grow bushy type of plants that are water intensive like blue berries.

boy howdy, exactly what I'm thinking. I'm planning on kiwi vines, have them already, too. One question I've mulled over: If the plants such as blueberries like water so much, won't this remove a lot of water from the AP?

jwnova99

Boss, that is one thing I haven't seen addressed much is the loss of water to plants natural means of perspiration. I'm in an area that gets plenty of rain fall to top off my tanks, but in between, I know my plants are giving my AP water away to the sky. The more plants I have, the more that will take place.

BenBrewcat

I'm a little confused on this whole earthan concept. I mean I get the concept (flow-through rather than just wicking), but what is the advantage? It seems like it would be much more efficient to add typical grow bed volume (for nitrification horsepower) and then if desired use AP water to feed wicking beds.

What does the flow-through add/provide?

boss

In my case the dirt grow beds are integral to the stability of the earth-sheltered design by raising the sunken aspect of the greenhouse which should greatly reduce temperature swings which are shortening our growing season by months. We're at 7550 feet above sea level. The dirt creates a heat sink and re-radiates heat absorbed during the day at night.

Food&Fish

boss wrote:

Quote:

I could then grow bushy type of plants that are water intensive like blue berries.

boy howdy, exactly what I'm thinking. I'm planning on kiwi vines, have them already, too. One question I've mulled over: If the plants such as blueberries like water so much, won't this remove a lot of water from the AP?

I would say that would be a plus your plants get good nutrient rich water and your aqua gets a water change plus all-round

jwnova99

Sorry I've been absence. All good points everyone.

BenBrewcat wrote:

It seems like it would be much more efficient to add typical grow bed volume. What does the flow-through add/provide?

Your right. I could use 20 IBCs cut in half, lined up on my hillside with wood and brick for leveling, but using ditches lined with gravel would be look more natural and cost a lot less in material and labor. The concept would be the same; a constant flooded AP grow bed. I was only using the wicking media on top of the rock to give the roots some aeration room. The flow through verse regular wicking beds is necessary to clean my 4000 gallon fish water inside my greenhouse. In WV, its mostly clay and hill side, the clay stays saturated on the flat areas and doesn't drain well, and each summer we have a 3 week dry periods followed by 2 weeks of constant rain. Farming here is tough. What if I could design a hillside farming method which drains into a fish pond on the bottom flat and uses an industrial pump to cycle the water back to the top of the hill. Using IBCs, wood and gravel, while neat, would be too costly on a large scale.

boss wrote:

IThe dirt creates a heat sink and re-radiates heat absorbed during the day at night.

Quite right. The constant flooded gravel beds being in ground will regulate temp and the wicking media on top would add insulation.

mattyoga

an advantage of an earthan bed is the potential to establish rhizospheric interaction with soil microbiology and make more nutrients available to the plants - the soil provides a carbon source and enables fungal establishment amoungst other things.... Though that can all happen in a plain wicking bed too. You also don't have to top them up like a wicking bed.

I'd be carfeful using float valve unless you have well filtered water or good pressure as I've had them block using gravity flowed AP water due to solids content.

I've been running earthan style beds F&D style for 18 months now and other than losing sight of my fish when it rains due to flush through I've had no problems - the system seems more resilient than plain gravel - I think that the earthan beds may improve nutrient availability - main thing I like about them is I can stick soil based plants straight in them, no root washing needed - and can direct sow much easier.

Gunagulla

My new system is going to be just about all wicking beds set into the ground, flood and drain, although I'm doing it to keep water temps down in summer for trout, rather than jwnova99's wanting to improve winter conditions.
A few pics posted so far here:
viewtopic.php?f=18&t=24153

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