Backyard Aquaponics
A place to discuss aquaponics

Yep, but all the tanks I've used so far are only two feet deep anyway.

I could see this working with EPDM because it's very strong and has a great deal of elasticity. I would worry about the exposed liner - easy to cut by accident or on purpose.

- Thanks, I knew about this but I didn't want to refer to it as 4 inches when it's not.

The ladies at Green Acres organics did the radius thing with their liner, you can still have the insulation around the outside to protect for temperatures as well as to protect the liner from easy puncture.

Actually I would worry a bit about EPDM stretching being more of a problem while I think the durascrim is less elastic. I'll be running some tests of both for things like this. Actually I have an old piece of EPDM that I've clipped between some pipes to make a settling tank and it seems to be working and I'll be getting the durascrim in a couple weeks to make a trough.

(This post is catching up on questions, etc. Next post will be an update)

I have been remiss in posting. After the flurry of "aaaaaghh, brace!" posts, I panicked a bit, and withdrew, and thought, and experimented, and stuff.

The long and short of it, though, is that Dave Donley is right with his "Radius" (suspension bridge) liner configuration. This configuration puts the tension, and the pressure, on the liner, which transfers it straight down onto the ground, leaving the walls mostly unaffected.



I bought the durascrim(tm) specifically for this purpose, because I knew it was this strong. Dave mentioned a pic that I took at the Friendly training that I posted waaaay back in the thread that demonstrates this rather dramatically:



I have screwed down lath (wood pieces 0.5' x 1') on top of the liner rail, holding it firmly in place. I'm not sure if I mentioned that before, but it was always part of the plan. It's visible in the pic below, and is screwed in about every 5 inches.



So now I'm going to go back and answer some of the pending questions.

I aligned them parallel with the walls in order to give me room to install the insulation. Since this is a commercial setup, it needs to look decent (or at least as decent as my "rustic surreal" style of carpentry can look). Also because I (knew? thought?) that most of the pressure would be on the inside of the rail.

Interestingly, the sides are bending IN, not out. Which is consistent with #2 of Dave Donley's drawings, but I barely pulled the liner taut. I think the line between #2 (tension pulling in) and #3 (neutral tension) must be very, very fine indeed. I did put a few bracings on the outside, and they're under no pressure whatsoever.

Turns out I need to brace the sides from the inside. With the liner pulling the sides in, my troughs are not 4 feet wide, as I'd planned. So my rafts don't currently fit correctly. I've had to rotate them 90º. But this is only one of eight troughs, and the next ones will be better. If I install inside bracings on this trough, the rafts will fit. The trough is only about 1" too skinny right now.


The Friendly's also use the really thin plywood on their active troughs. Its there to protect the liner (and in my case, the insulation), and not for any structural reason. A weed wacker could cut through the liner easily enough, with disastrous results.

These troughs are about 19 inches deep. I shortened them from my planned 24 inches for this very reason. The side studs are 16" long, and the horizontal 2x4s add the extra 3".

The blue insulation I'm using on the sides of the troughs is scored DOW blueboard, and so each 4'x8' piece breaks conveniently into three 16"x8' sections, as seen in this pic I posted earlier:

As you can probably guess from the last monster of a post, the last two weeks has mostly been confirming and double-checking my design. Better safe! My troughs, currently, don't even have any posts pounded into the ground. There are two rows of alternating 2x4s along the bottom, and the bottom rails, but that's it on the bottom.

Anyway, the first trough is mostly finished, except I haven't drilled the exit hole. I got so fixated on checking the strength of the walls that I forgot I can't drill that hole when it's full of water! No worries. I'll pump over the side for now, and drill it when I complete the second trough, and move the water over there.

I've got my gravel for my 100gal stock tanks, and one tank has been filled with washed gravel.


I've insulated and cladded the fishtank for this greenhouse, and put in the uniseal:


and started planting!


For right now, I'm just planting straight into the rafts with 2" net pots filled with a mixture of 75% coir and 25% vermiculite. I've been trying some with gravel (a la Coastview Aquaponics seeding technique) but so far those are taking a lot longer to germinate, but that may have been a fluke. I'll run more tests. I'd prefer to use gravel, as it's cheaper and easier to reuse, but we'll see. (Cinders/scoria isn't really a renewable resource in Minnesota, so I haven't looked at it terribly closely yet).

Today I worked on plumbing up the fishtank to the gravel beds, and I should finish that up tomorrow. Hopefully I can have a complete (with just one trough) system working in a few days, and be ready to move my fish to this system.

So far, I've planted:

• Tatsoi
• Mizuna
• Nastutiums
• Caraflex cabbage
• Cucumbers, lemon
• cucumbers, Armenian
• Romaine (cos) lettuce
• Arugula
• many fancy non-cos lettuces
• pakchoi
• vitamin greens
• Basil - Aroma 2, Sweet Dani, and Amethyst
• Savoy-leafed spinach
• spaghetti squash
• stevia
• watercress
• Cilantro

As I've mentioned before, my water is extremely hard, so it should be interested to see what I can grow! I've not yet started to try to soften it or mess with the pH, I want to see what happens as is, first.

Oh, forgot to mention, seedling tables and seedling rafts are coming, but later!

That all sounds great Karen!

In the picture of the IBC it looks like there are little slits cut in the end of the pipe. Is that to help it get through the uniseal or something?

Great to see things get filled with water Karen, thats a bit of a milestone ..

Check this thread of a hydroponic farm I visited a while back, he used compressed peat seedling punnets with a mix of vermiculite and something else in them, made his work simple when it came to planting out, he just broke them open and dropped them into their growout position once they were big enough.. http://www.backyardaquaponics.com/forum ... hydroponic

We cut our pipes like that to get them through the uniseal DD, I assume thats why they are cut like that, makes it a lot easier.

Yup, the little cuts on the end of the pipes are for uniseal easiness. I'm not sure it would be possible to get 3" pipe through a uniseal without those slits! At least with my (lack of) upper body strength.

Thanks for the reminder about that hydroponic setup, Joel.

So, I had the first gravel growbed unisealed, tested for leaks, filled with gravel, and had the water distribution grid done:



I had started testing the grid, when my toes got all wet. The (already tested for leaks) uniseal was not just leaking, but FLOWING water. Gah! So today I emptied the gravel (it didn't take nearly as long to move 100gal of gravel as I expected, is that a good thing?), and hauled out the pipe from the uniseal. I think the leak was due to gravel getting under the seal.



Tomorrow, I'll fill the stock tank up again with gravel. But first, I'm going to ring all my uniseals with silicone, so the gravel can't sneak in under the lip again!

Also, the SLO for my first fish tank:



I got the idea of that green grate from TCLynx, I think. It's an "atrium grate," found in the drain tile section of your local giant box hardware store. Alas, I couldn't find one small enough, so the ever-handy cable-tie to the rescue again!



The hole for the water overflow is pretty high, so I'll probably either cut down the T, or rotate it 90º, and see how high that makes the water.

I know SLOs are traditionally in the middle of the tank. I'm going to try it on the side, on the theory that IBCs are small enough that it won't matter. If solids do build up, it'll be easy enough to add in a length of PVC to move the SLO back out to the middle. But everything is much more solid there on the side. My "middle of the IBC" SLOs tend to tip over.

Clean. I had noticed TC's tidy setup and had thought it was a net pot. Thanks for sharing that detail! I've had the drain rotate too. Maybe drilling a hole and putting a screw in the fitting and pipe would do the trick. I'd be tempted to cut off some of the tee, but mangling it would be a shame. Shouldn't see the water go over the edge in normal operation, so maybe test a blocked pipe scenario to see if it needs to be adjusted or not. I hate to think of the scenario that would block the bottom then cause the overflow to block too. Your pipe diameter seems plenty big so in normal operation I bet the water level doesn't get near the top of the tee.

Yep, atrium grates (anyone know why they call them that?)

On my tower system the flow comes a bit over half way up the horizontal on the Drain but it doesn't have far to go once it leaves the tank and it is draining into a sump that is a fair bit lower than the height at which the water leaves the tank.

I have used some stainless steel screws or zip ties (so that I can when necessary unhook the pipes) to secure any non glued pipes or grates on my SLO's to keep the fish from knocking the piping out of place. My big catfish are definitely able to pop an unglued pipe out of place as they have done it before and having a 1 lb catfish swim into a pipe it can't easily swim out of tends to really stress them out.

Had to empty the whole gravel bed out??? It's not like you have anything better to do...

Hope it seals properly for you second time around..

TCL....atrium grates are used in buildings that have open roofed atriums, they are simply like a bathroom drain with a cage to deflect leaves etc.

Update!

I have a new friend out at the GH:


It's a woodchuck, I think. Jones chased it under a growbed. I've barely seen the poor critter, this was taken by putting my camera down the hole...

I have been, among other things, building the second trough:





Clamping the sides as we go:


Making sure the corners are taut:


Nicely folded corner:


And then I proceeded to completely hash putting in the uniseals on BOTH ends. I think I'm going to have to pull this beautifully done liner out and use a new one. Very expensive mistakes...

I'm not getting great growth on the seeds I currently have planted, and what I do have is getting eaten by caterpillers. So over the weekend I sprayed BT, and today I sprayed compost tea. I think I'll need to get some row covers, and make a regular compost tea batch until I get more fish. Plus, since my pH is 8+, a regular folier feed will be needed, I think.

I've bought some pool acid, and will start experimenting in a 5gal bucket with bringing the pH down, but I doubt it'll work, the water is simply too hard.