DD's System 2011

Dave Donley

I will draw up the PVC and liner trough idea cross section, I think it's promising, only two common materials needed.

Dave Donley · Screen shot 2011-02-08 at 2.10.22 PM.png [ 82.48 KiB | Viewed 1704 times ]

There is a pipe down the middle to make sure the trough doesn't overflow, if the media might not flow fast enough from one end to the other.

Dave Donley

Latest thoughts are that white shade cloth could be used instead of landscape fabric. Some kind of light color needs to cover up the liner and media (if it's charcoal).

Instead of threading the pipe through holes in the liner, the snapping-type connectors for greenhouse plastic (plain segments of pipe sometimes) might be used, if the water and liner aren't too heavy for it. Supporting the media and plants by suspending the fabric/shade cloth lightens the load on the liner to just hold the water weight. Also that would reduce the flex in the 90 degree elbow, if the pipe ends were not holding up the plants and wet media but just the water.

TCLynx

It might be cost prohibitive but hdpe liner might be strong and ridged enough to handle supporting this provided the edging you attach it to is sturdy enough.

Dave Donley

I have ton a HPDM PondGard liner from my AquaPatio days that I never used, that stuff is very tough.

Dave Donley

Correction: EPDM, i.e. the good stuff.

TCLynx

Problem I see is the EPDM is stretchy and therefore can't support much weight though it is very tough stuff. Slits in it to run a support pipe through seems like it would tend to rip. Now if you could clamp the edge tightly between something then you might be able to support a bit more.

HDPE is ridged enough that you might be able to have the liner support some weight.

Dave Donley

I sense an experiment is in order (that's the next step, to try prototyping one or two designs). Should be straightforward because I already have all the materials. I like to sit on these designs for some time because they get more optimized the longer they brew.

Dave Donley

This morning's commute was about thinking about trusses and I-beams. I am trying to find a link to a tomato greenhouse where they used welded rebar joists to make a lined V to hold the plants, suspended from the greenhouse frame.

A triangular truss could be used outright as a bed frame, wrap liner either outside or inside it, maybe with wire mesh to manage stretching. The liner could be within the truss, or the liner could be hung down from it. If the pipes were fish-safe then the frame could be within the bed rather than outside it.

It's the same problem as bridge construction, many ways to suspend a load over a span.

If the side rails can be stiff enough then that may eliminate the need for the top brace, to either eliminate pieces or make the span longer. This says 3 2x4s nailed to form an I-beam can be >10 times as strong as a single board. Or an I-beam could be used for the top rail to hang it from, I had been thinking about a single board or maybe galvanized steel pipe.

http://answers.google.com/answers/threa ... 70229.html

Dave Donley

TC you're in the entertainment industry, have you ever looked at light trusses as potential grow beds? :headbang:

Dave Donley

Weather is warming up - it's supposed to be above freezing all week!

I turned on the pumps today! I will probably unplug the sump pump to the gravel, but keep the small pump going to keep things moving and maybe keep ice from forming on top.

Been running through several ideas today, and went to Lowe's to price supplies.

I had thought that I could pile a bunch of charcoal in one half of the FT longways, separated by screen, and plant plants into it. Did an experiment though and the charcoal does not push up out of the water like it does when it is new. If you stick your finger in it there is not much pressure at all, it's pretty much neutrally buoyant. I think you can still take advantage of that, since the media basically has zero weight in water, that reduces the need for support, maybe just lift it up from the bottom just to have a dry layer for a few inches down.

The other thought was to turn buckets upside down and use to charcoal to float them. A hole in the bottom (now the top) would be planted. A lid on the bottom would keep the media in, a weight dangling from the bucket handle would stabilize it rightway up. Now since the charcoal seems to be neutrally buoyant I guess a layer of foam could be put at the top, at the bottom pushing in the charcoal, or around the outside edge, but I'm not sure what advantage that could give over just styrofoam sheets with net pots in them.

I plan to collect the solids and aerate them, with this floating bed thing there could be many small digesters working rather than single large one, using air lifts to suck solids from the floor of the FT and rattle them around inside a can, then let them diffuse out into the media:

http://www.backyardaquaponics.com/forum ... 25#p249525

Dave Donley

Here are pictures of the "Outback" system today.

I want to get two things going besides the gravel beds.

1. Take a drum and put airstones in the bottom and make a settling cone in the center, using pipes widening from 3" to 4" to 6". 6" pipe was $35 (10' only) so I am thinking maybe instead to attach the 4" pipe to a bucket or other. Uniseals out of the side of the settling cone and out the side of the drum. This would drain into a "clean sump" (stock tank) with hopefully few or no solids. The clean sump is intended to house any pumps to other beds and things. The clean sump overflows to the FT. Solids would hopefully stay in the digester and be broken down into liquid nutrients. The digester would have a backflush valve to drain it some if necessary. I estimate this will be around $100 to make.

2. "Rendezvous Lagoon" cold frame. This will be some kind of enclosure with shallow trays for setting (sub-irrigated) planters in for soaking in the AP water. The planters will be used for nitrate removal only, so they can be watered only at the bottom of the planter. The lagoon will be wide enough to set anything from the small planters I have now, larger ones, buckets, laundry tubs, up to storage tub sized SIPs. There might be two lagoons stacked vertically in there, fed by a pump in the clean sump. Hopefully the planters will remove nutrients from the water, until troughs/beds can be fashioned to grow a lot more as the weather gets better. Buckets would be cheap to use, and I'm thinking about whether gravel in the bottom and only charcoal in half the planter could work, to save $. 12" planters plus charcoal to fill them worked out to like $12 per planter, but I think cheaper ones could be found and maybe gravel could be used in the bottom and mulch on the top, with only a middle layer of charcoal, if that may be cheaper...

Dave Donley

BTW the pile of rocks is a warning to anyone who might think about digging a hole in our yard.

TCLynx

I generally hadn't thought of using lighting truss for grow beds though it has crossed my mind once or twice. Biggest issues is it often has diagonal braces inside it so you would have to make an effort to get the plain ladder truss that doesn't have that. But mainly, it is probably far more $$ than many more suitable materials.

Dave Donley

Today was such a great day for doing AP! It seems that this time of year is pretty good for preparing the stuff for Spring, at least this year. The weather was in the 40s today. I did some work on the little indoor setup, experimenting with things to use with the outdoor one.

Rendezvous Mark II is in progress.

Since I started using air lifts, I have been wondering if an air lift could be used as a kind of solids barrier. The idea is that if a piece of solids was trying to leave a container, and the only way out was streaming with small bubbles, then it would be like going against the wind. I had thought maybe the water could get through but solids would be discouraged for lack of a better word by the bubble stream.

So today the first thing I did was try to make a solids digester using an air lift to keep the solids in the container.

Backyard Aquaponics
A place to discuss aquaponics

DD's System 2011

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Backyard Aquaponics A place to discuss aquaponics

DD's System 2011

Who is online

Backyard Aquaponics
A place to discuss aquaponics