Backyard Aquaponics
A place to discuss aquaponics

I'm planning on making it to fish farming eventually, but for now, we're raising ducks and have a small pond (<500 gallons). The water gets nasty dirty from the ducks and I'd love to use an aquaponics type system to filter the water, make use of the organic material, get the bacteria going in some growing beds and try out the idea.

The pond is in the ground and I have a dozen old bathtubs to use as grow beds. I'm thinking to put the bathtubs on cinder blocks to let them gravity drain back into the pond. We have cheap access to lava rock, so I'm thinking of using that for the growing medium, around 12" deep seems to be somewhat of a consensus? The tubs are 24" deep, so 18" deep of lava rock would be no problem.

I've got a small solar panel/pump set up (~100 g/h) that I'd like to use to help keep costs down. Is flood drain the best/only method for helping bacteria spread through the medium and handling the water movement or are there any strategies for working with a small but constant flow of water (during sunlight hours)?

I'm open to any and all suggestions, I'd love to find out if any folks in the area have a system up and running and I'm looking for tilapia connections for northern California as well.

Thanks,

Rick

Welcome Rick... have a look at Duckponds "duckaponics" thread perhaps...

http://backyardaquaponics.com/forum/vie ... =18&t=2885

Yep, definitely read that link since Duckaponics has been done successfully.

I expect that daylight operation for a duck pond might be just fine, at least once the bacteria get cycled up. That is provided the pump is strong enough to handle the nasty duck water and poo.

I don't think I would trust an AP system with fish in it to just a small solar pump since the fish depend on the flow and filtration for their vary survival, not just comfort and enjoyment the way the ducks do.

Good Luck and welcome!

Hi. I think that you will need to filter the duck water very efficiently. Maybe a clarifier to trap the heavy solids and a filter to take care of the suspended solids. It may also be better to keep the system working even at night because the bacteria also need oxygen to survive and be effective. Good luck.

Seems like a quack thing to me

The Dissolved oxygen in duck tanks is often very low, so be sure to find a way to oxygenate the water before the bio filter! To break down that kind of muck I would suggest "CHIFT" and a digester tank. Take the water off the bottom by gravity or raising the tank water level. From there the water needs to enter a settling tank where it can digest anaerobically then flow over to another tank where a pump is runs 24/7 blasting air into the water. You can pump nutrient water from this second tank to grow beds then return the growbed water to the duck tank. The combination of aerobic and anaerobic digestion tanks will break the waste down quite fast and it would help greatly to not pulverize the poo in a pump before you settle it. Now, if your duck pond is deep enough you might be able to let it be the anaerobic tank/duck tank as it is now, but I'm not sure how healthy that is.

The only problem with digesting waste this way is that you are going to have a LOT of nitrogen, so be sure to have plenty of nitrogen hungry plants.

I must post up my modified duck system soon......

It does take a lot of filtration and a grease trap to do well in my opinion, despite my best intentions I have a small filter mat that I clean of every couple of days otherwise sludge builds up in the filter plant/green filter bed of my system.

Due to limitations on space and layout I can do no more, however if there was a next time I think I could make it lower maintenance with a quick scoop out every month only , would require custom work or expensive pre made goods to achieve I think

The Fishpond and growbeds however function and are as clean as any other system so I am happy in that regard

Here is the link to the original Duckaponix
http://backyardaquaponics.com/forum/viewtopic.php?f=18&t=2228

Hi, Rick!

Flood/drain works best in my book as a constant trickle will lead to some spots being dry and others being anaerobic. The big problem with flood/drain is that you have large volume fluctuations, especially with ducks as they produce so much waste. I figured (roughly) that ducks will produce about 5X as much waste as fish, so a lb of duck will require at least 2*5gal of growbed (or 3 gal of water). I figured a flock of 20 could support a 4'x24' growbed and would require a 250gal sump and 250GPH pump or better. Ducks don't really require the same water quality as fish, so you could pump less often..



Where, exactly, is Urban, CA? *grin*. You can certainly come see my system if you are anywhere close. I also know an intermittent source of tilapia.

Ok, I disappeared for a bit while I was thinking and seeing how things were going with my budding duckaponics system. So flood and drain with a small solar panel powered pump doesn't seem likely. So I'm thinking about designing for the nutrient film technique, it seems to match my available conditions best. Some things I have going for me are a huge green house where I start all the plants, so I can wait till the plants are busting out of a 4" pot before I plant them in the lava rock I'm using as my grow medium. What I think that means is that the plants should have enough roots up high that don't live in the water film at the bottom so the plant doesn't drown, but there will be enough roots to access the nutrient film flowing by to make sure things get water/food.

My guess is this kind of system doesn't work as well in a broad bed (too many chances for the water to flow in a path that skips some areas and gets stuck in others) so is the best strategy for NFT to use 4" (or larger?) PVC? The one thing I don't quite get about NFT, in a flood and drain system, I get how the bacteria gets around to all the growing medium up to about an inch or so from the top because of the flooding. In and NFT system, how does the bacteria get around? Or does it only live in the bottom inch or so of the system?

So here's a broader question about what I don't understand (and I'd be happy for a link to a pre-existing answer if it's there), in any kind of aquaponics system, is the bacterial action of turning amonia and nitrites and nitrates into nitrogen an incredibly fast process? Even in a flood/drain system, the water floods the grow bed, but then drains out reasonably quickly, so does the bacterial action happen inside of ten minutes or so? And then the nitrogen it produces hangs out long enough for the plant roots to access it?

So for an NFT system, the length of any single PVC section would seem to be a huge issue. How long can a section go before the water making it to the end has nothign left to feed with or the combined resistance of all the length of lava rock/roots/plant containers causes so much back up that the system does more flooding than filming?

Last question. So far I've been running the solar panel every day, but the pump is only 90 gph for a 400+ gallon tank. Because of the challenges of powering a pump off of a solar panel, the pump is not even running at 90 gph all day. Fairly frequently I come by and manually flood the system as I'm trying to build up the bacteria. I get the ideas about testing the water in the pond as a way of telling if the bio-filtration is working, but since my one little bed with a wimpy pump can't come close to cleaning that pond, is there anyway to know if my lava rock is getting nice and filled with bacteria? If there are cloudy days where no water pumps and two to three day stretches where I don't come by and manually fill the tub once or twice, is my bacteria dying faster than its growing?

Thanks for all the help,

Rick

p.s. Hydrophilia, I'd love to come see your system, I'm in Oakland, but wouldn't mind the drive

The bio filter action only happens in media that gets wet (and never dries out completely) but has enough aeration that the bacteria can still function. In NFT that would only be in the thin film on the bottom of the trough so you don't get nearly so much bio-filtration from an NFT system. You get far more bio-filtration per square foot from a gravel filled flood and drain bed.
Also, NFT is going require a pre-filter to remove solids before sending the water to the trough or they are going to gunk up and the plant roots will have trouble with rot and not enough aeration for the bacteria to work.

I think the biggest problem for the small solar pump is the problem of solids clogging it up. And if you let your flood and drain gravel bed dry out completely, the bacteria are likely to die off and you will have to cycle backup again.

For a duck pond system, I think you probably need as much flood and drain gravel beds as you can get to handle the solids. I suspect NFT will only cause you problems. Duck solids are far more copious than the fish solids.

As to where in the system stuff happens. Nutrients tend to be in solution and flow around the system and they do not get used up in one pass. Don't worry about it happening in one pass through a trough or anything (it isn't like a RO water filter where only the perfect stuff makes it though.) The actual bio-filtration happens in the thin film of water that coats the media which is where the bacteria live (actually in the thin coat on just about any surface that doesn't get too much sun light provided it is wet yet has access to oxygen.) The bacteria change ammonia into nitrite and other bacteria change nitrite to nitrate and it is the nitrate that the plants use. Continually or regularly moving the water through the system is what allows this to work to clean the water. At least with ducks, dirty water won't cause them to die overnight due to lack of pumping since they breath air rather than water like fish do.

Ok, so here's maybe a bigger question that doesn't just have to do with duckaponics. This project is part of a larger garden project and we're constantly looking for ways to get more nutrients for the plants without having to pay for it. Water is reasonably cheap, so what if instead of using plants as a biofilter for the water, I just pumped the duck water straight into the rows of plants we have growing in the dirt? The solids are no biggy now, as long as I have a system for distributing them, and if they built up in a spot over time, shovels are easy to use :-) Our soil is reasonably airy, it's mostly mulched (to keep out light and keep soil moist), and if the biofiltration can happen in a tiny film of water sliding along the bottom of a pvc pipe, wouldn't it happen in the top layers of dirt as well?

This way I get the solids out, I get much of the nasty out, I refill the duck pond with clean water and use the duck water straight as it is. I'm not sure I'd be able to reach the whole garden (about 1/2 an acre, 300' x 60'), so I wouldn't use it all the time, but especially during the summer, it'd be at least every other day, a few hundred gallons. Obviously this type of system isn't anywhere nearly as water efficient as aquaponics, but since we're using that space anyways, and we have to water it ...

If this idea seems workable, any idea for a good way of distributing the water along a 30' row? Soaker hose would trap too many solids, pvc drain pipe seems possible, but most of the water would drain out from the first 10' or so of the pipe and the last section wouldn't get much. A custom made pipe with smaller holes towards the front and increasingly larger holes towards the back?

to spread duck water along the rows you almost need to bucket it out there. Any "irrigation" system other than using spillways and channels is going to have trouble with clogging. I've done some of my new garden beds as kinda raised mounds with the walkways being trenches that I then filled with wood chips, I can then use these trenches to help deal with drainage around the house. I don't know that this method would really work for duck water since it isn't delivered up around the tops of the plant beds.

Perhaps you could run some geo-textile tubes along the plant rows and run a large discharge hose into the end of them then pump the system out into one of the tubes. The solids would collect in the tube to break down and the water would flow out to the plants. The tube could act kinda like mulch on top of the ground. You could pump the water to a different tube each day. I don't know if this would really work all that well but it is the best idea I can think of.

+1

One could use it as liquid fertillizer, applied from a hose. Have a pump feed a hose and walk down the rows. At 5gpm you would run through 300 gal in an hour.

Advantages over AP:
no gravel, growbeds, sump, and other expenses
more foolproof

Disadvantages:
requires time and effort
requires dedicated hoses (don't drink from them!)
dragging a hose is a great way to uproot plants (although raised beds or guide stakes really help)
sitting stagnant, even for a day, might make for stinkier effluent: not appetizing for a garden
requires that people who water make sure to keep it off the veggies
that are eaten raw and requires that others trust them to do so.

Another option would be to have what is essentially a mound septic systems with a mound of soil with some drain line that gets filled from the duckpond and then soaks into the soil. Technical issues would make this problematic, though. Eg: how to get even flow to perforated pipes without excessive cost, effort, spattering, or smell?

So what I'm thinking of doing is using a bait tank pump, the kind on a fishing boat. Those are great for pumping out solids, not getting clogged, they're designed especially for situations with nasty solids. THey also run on 12VDC, so if I get a few car batteries, use my solar panel as a trickle charger then run the pump a few times/day for just a couple of 2 min bursts, the pump piece hopefully should work.

The best I've come up with for water distributing is using 4" pvc perforated drain pipe, in 10' lengths, since my beds are 30' long, 3 strung together. The rough volume is 3.14 x 1/6'^2 x 30' which gives a bit over 2.5cf which is just under 20 gallons. So I put a cap on the end of the 30' section of pipe, turn the pump on for a little over a minute (it's a 800 gph pump) and the 30' section fills up and then slowly drains out. I make sure to have the pipe laid out such that the drain holes are right at the bottom and that there's enough room for the water and some solids to drain out (maybe the pipe is elevated a tiny bit? I'd have to operate the system manually, and for most of the beds, once things get growing, it'd be too hard to move a 30' section of pipe with the plants growing all over it, so I'd have to invest in a bunch of pipe. 10' sections go for about $7 out here, so that's not too bad, since they should last pretty much forever. Assume I can get the pipes roughly level or that I put plants that need more water towards the sloped end.

I could design a simple pvc connector on the 30' pipe sections in the beds that accepts a tube from the pond pump, I manually hook the tube up to a 30' pvc section, turn on the pump for a minute plus, disconnect the tube, move on to the next row. Fertilize 20 beds in less than an hour, move 400 gallons of water, refill the pond with clean water, do the same thing every other day.

So, a couple of questions. First, any thoughts on the pump/distribution system? Obvious problems, easy improvements?

Second, I'm still wondering, how "nutritious" would this duck water be for plants given whatever bacterial systems will be in place in the top few inches of soil in the soil beds? Would it be every bit as good as a fully functioning aquaponics system? Would the top inch or two of soil (assume good quality, airy soil with mulch/plants to block out light and it stays at least somewhat moist a few inches down) work just like whatever grow medium in an aquaponics system or not as good?

(This is the pump I'm thinking of, any thoughts?): http://hopkins-carter.com/store/p515/80 ... _info.html

Thanks for any thoughts (and I think I'll repost this under a new header so I can get more folks to way in on the bacterial bit, that confuses the heck out of me still)

Rick