Backyard Aquaponics
A place to discuss aquaponics

Read my newbie intro for a general overview..

So in building my first system I had a few things I definitely couldn't do. For one is have my beds lower than the tank. (23,000 gal below ground pool) nor a sump. I also didn't want to mess with timers for right now. So this is what I came up with. First, a 100gal stock tank.

Then a grate at the bottom with some pvc with large holes for support. (pictures are going newest on top, sorry)
Then I put bio-barrels on the bottom. It looks more than it is because the bottom 4" are filled with water and the barrels float. On top of that went 2" course mesh filter material. Then came the clay. I made a grid to flow water down, and put a 40w 10gpm pump into the pool. I put in an over flow valve not knowing what kind of pressure I would need to the grid. With head it's probably running about 7 gpm, which I could probably increase in future beds. I'm going to fit it with a garden hose fitting so I can attach a hose and pump out water when the occasional week of rain comes and it looks like an overflow (it's happened). Only the bottom 4" stay flooded, and I seem to be getting a good spread in terms of water distribution. I put a valve on the output so I could flood the bed if I put on a cycled timer, I'm just going to wait and see what it does for now. In hindsight I probably should have put a small air stone in the bottom, which I'm going to due with the next beds if I stick with this design. I can only attach three files so I will make another post.

I don't have any good pics of the little veggies, the weather has been really overcast, will post some soon. I don't have a pic
of the return. It's simply 1-1/4" pvc with a valve using the factory threads on the tub. I put in a 45 dg bend to reduce evaporation. The pics are about 4 weeks old and happy to say the algae (nice bubbles hey) has gotten alot better, but still has a long way to go. At least the Tilapia have an all night buffet.

Hi Troy,
Not being a detractor in any sense, but those tiny holes in your distribution grid are going to block with biofilm pretty quickly and are gonig to need cleaning pretty often. Especially hard to do when they are on the bottom of the pipe grid.
I overcame this problem by putting 6mm slots (cut with a Router) along the distribution pipe,

just above the centre line to give a bit of freeboard to stop solids from blocking them. I just give the slots a wipe with my finger when I see a bit of gunk beginning to clog and they operate fine. Sorry, no photo, I'm at work, so I hope this sketch will help.

And you could do worse than turning your pool into a "natural pool" (google it!) so so get the best of both worlds.
Swimming with fish!!

Cheers IanK

very cool, do you cut on both sides of the pipe? I wonder if I would need more water pressure to add a couple of of slits to
the inside pipes of the grid. The water flows pretty good right now but is in no means 'squirts'.

Troy,
Just one side of the pipe so I can see them clearly; I only have a single delivery pipe from the Fish Tank down one side of the Grow Beds. The flow rate doesn't really matter because of the pipe (and therefore the slots) being horizontal, the slots act as a "weir" and only deliver the available amount equally along the length of the pipe with the far end being capped. I have also put a small drain hole (8mm diameter) at the capped end just in case the pump stops and allows any standing water to drain; instead of staying in the bottom part of the pipe to become stagnant. The only thing that changes is the depth of the water in the height of the slot. Mine don't get above half way for the flow rate I need for my Auto-siphon.

This photo shows the GB layout with the valved Supply pipes at the rear of each GB. This photo was before I put the continuation of the delivery pipes, but you can see the intent.(this was also before I put Media in the GB's!!)
I would plug your existing holes (or just let them block over time) and then the wier slots will kick in and take over the distribution duties.

Cheers IanK

Nice set up Troy, those tubs look great for GB's.

One thing to consider, that clear hose running from the lower tap to you distribution grid may clog up with algea due to sun light. Best to use pipe that won't let light through.

Can you explain a bit more on how you drain the GB? How the 45deg bend is set up?

Can't wait to see a heap more GB's all around the pool/FT with 100' of fish. Throw in the fishing line while sitting back on deck chair .

For real on the backyard fishing. I plan to add bluegills in the spring once the tilapia start breeding. That is if I can keep up with filtration.

As far as the drain, it drains freely from the bottom front side of the tub. There is a valve to do whatever but is wide open at the moment (and I hear a little gurgle= air? )the 45 angle lets me shoot it closer to the top of the pond.

Just so you all understand.
That grow bed Troy currently has set up is not flooding and draining at this point in time.
The top clay layers are just trickle through from the pipe grid and the bottom bio-barrels are constantly flooded since that is about the level of the drain plug.

I've tried to convince him to do some flood and drain but he hasn't gotten around to it yet.

He does currently have an old sand filter (or I think it had actually had DE in it) that is empty now. We might suggest something to put in it to improve his filtration. The big pool pump is currently only running 6 hours a day though.

The 100 gallon stock tank has it's own little water pump.

And there is an air pump running some air stones and the wheel filter.

The only thing that concerns me about flooding the tub is

A. back washing the 2" mesh filter
B. I'm in the wide open with everything, and a lot of rain could screw with the flood level

Is it a matter of water distribution for the roots, surface area for bacteria, or oxygen for all that is of concern?

Flooding and draining gives the best of both worlds to the bacteria and roots. They get good water coverage during a flood and then the water drains away allowing air in so they can work then it all repeats.

With a trickle flow, the water will tend to follow a path and areas of the media will stay dry while other areas will stay really wet. The bacteria has less functional surface area to work with.

I don't think flooding and draining of the little grow bed will have any issues with leaves or rain messing it up or causing any real problems. You just have to decide if you want to put the little pump on a timer and close off the valve from the bottom of the stock tank a bit or if you want to leave the little pump running full time and work out a loop siphon for the grow bed.

I still haven't grasped the loop syphon concept quite yet. It seems a mechanical way of flooding would be preferred over an expensive cycle timer though.

Loop siphons are as simple as Troy... and work well with small containers...

Here's my half barrel system with loop siphons...



As the half barrel fills... water rises in the black tubing... until it gets to the top of the bend.... expelling any air... and creating a fast draining siphon action...

Once the barrel is empty... air is sucked into the barrel outlet... into the tubing... breaking the siphon...

The top of the bend in the tubing ... sets the flood height in the growbed....

Rupe,

I don't think Troy is " simple"? are you Troy? I think you are quite intelligent!!

But, Loop Siphons are very basic in their construction and operation.
Have a look a the description I did for a paper earlier in the piece.

This one is a bit sophisticated, with a media shroud, but you get the idea. Rupes basic one is just the looped pipe outside the GB. Oh, and don't use clear tubing . . . algae!

Cheers IanK

Above is how I do mine in the commercial system

Oh, and if you want to go simple timer flood and drain. It does not require an expensive cycle timer. A 15 minute interval outdoor mechanical timer will handle that little pump just fine. They cost around $15 I think.

http://www.amazon.com/Woods-59204-Weather-Outdoor-Repeats/dp/B0014WRNNK/ref=sr_1_10?ie=UTF8&s=home-garden&qid=1259242264&sr=8-10

Only question is, if the valve near the bottom of that tub were mostly closed. How long would it take that little pump to flood that tank to within a few inches of the top?

And If you decide to make the modification to flood and drain. You will probably want to install an overflow from that stock tank so if for some reason the main drain got clogged, the bed couldn't overflow completely. This would be pretty easy and would probably be a good idea even if you don't switch to flood and drain.