Backyard Aquaponics
A place to discuss aquaponics

I'm in the planning stages for my system. Our climate tends to be mild for our latitude (45°N) with typical high temps in the summer near 30°C and lows in winter of 0°C. Highest temps are closer to 40°C and lowest are -15°C. The system will be located outdoors and will eventually have a greenhouse built around it.

I'm thinking of using two IBC fish tanks, buried about 2/3 to help keep temperatures stable. There would be a ladder rack of 10cm pipe drilled with 7.5cm holes with the rack tilted 45° from vertical over the fish tanks. Pipes would be 3m long and angled enough to give a 7.5cm drop on each (which means about 12-13cm drop if the rack were vertical). There will be one or two grow beds either at one end or in front of the ladder rack to give plenty of space for bacteria to do their thing and to allow for some bigger plants. I might also seed these with worms. I'd expect to use a swirl filter to remove the bulk of the solids.

First question, could I trench between the two fish tanks to allow for water circulation between them, give some shallower area for water plants and possibly give a safety zone for fry (hoping for trout, may settle for bluegill or crappie)? I'd like to get the fish self-perpetuating as a 'nice to have' goal. The word 'trench' is a bit of a misnomer here, since it'd actually be an elevated roadway, about 1/2 of the width of a IBC and about 75-100mm in depth...

Next question, ignoring oxygenation needs, could I pump out of the bottom of one fish tank and deliver return water to the bottom of the second fish tank, setting up the flow through the trench? I'd have to add bubblers or spray wands to add oxygen to the water.

Another question, should I use two pumps, one from the FTs through the SF to the GBs, drain the GBs to a sump and pump from there to the top of the ladder? Or would it be better to pump through the ladder, to the SF, then GBs and finally to the FTs? We're talking two rises, one of 2m (bottom of FT to SF) and a second also 2m (from sump tank to top of ladder) or close to 3m of head in the 2nd scheme. I expect either way I'll be using piping between 25mm and 50mm for the pressure portion of the cycle.

Finally, can I stress the PVC enough to angle the joints the needed amount to give my 40:1 drop I'm planning on? Or am I asking for fatigue cracks over time?

Really finally this time... What am I forgetting? I'm planning on going the arduino with sensors route to gather data while running, even if it's still not viable to measure ammonia, nitrite and nitrates (here's hoping someone will kickstart a 3in1 sensor for that soon) I can do a good job of monitoring temperatures, possibly Ph, and alarming flow issues. It'd also be kewl.

So what do you folks think of this pump? It's got plenty of head, so I could pump from the bottom of a fish tank to the top of my ladder and still do 1000GPH. I figure better to be oversized and use the excess to help aerate the fishies than sizing just what I need and have to boost if I find I need to expand.

I'm also thinking of using a third IBC cut in half for the two grow beds... It would save me from having to source something else. IBCs seem to sell for $100 each around here if they haven't been used for something nasty. There's one seller with better prices on totes that have been used for silicon carbide, but I'm not sure how tough that will be to clean out.

@ 370 watts for 1000 gph I think there are better choices. The one I use is about 100w for over 2000 gph.
Look at fountain pumps or read thru viewtopic.php?f=8&t=1409&hilit=good+pumps+bad+pumps

pump seems a bit big for 2 IBC FT's 2500 (US)g/hr is about 8750L/hr your head is only from the FT water level to highest outlet.

not sure what you mean by "trench between FT"?

I would pipe them together, otherwise use 2 smaller pumps.

25mm sounds right for water supply pipe into an IBC, but the NFT (100mm tubes) won't need that much water.

I have been figuring using approximates of 300 gal each for the two fish tanks plus 200 gal for the two grow beds and some more for the pipes, so 1000GPH seems like it might be bit much, but not out of line too much. The lift is from the bottom of the buried fish tanks to the top of the ladder, a bit less than 3m, say 8-9 feet. That pump is 2500GPH at 0 lift and 1500GPH with 10' lift. Definitely over sized but I figured I could redirect the excess back to the fish tanks as spray, oxygenating the water. I've been worried about not adding enough oxy, especially with constant flow beds...

I've been wading through that thread, but am having a tough time telling the good from the bad at my size needs. I know I want 1000GPH or more with 8' of lift, so 1500-1800 at 0? The one you use sounds like it'd be about right, but I haven't seen your post yet as I go through the pumps thread.

Slowboat, the trench I am visualizing would be something like a rectangular tub with the ends cut out, attached and sealed at each end to cut-outs in the sides of the tops of the fish tanks. It would allow water to flow freely between the two tanks while giving some shallows for planting something like watercress, lilypads or other aquatic plants. It would be shallow enough to not be attractive for full sized fish to swim between tanks, yet big enough to allow for 1000GPH to flow through without washing the plants out.

Figured out one thing that's wrong with my design... I have to keep the flow through the NFT "ladder" slow, so can't do the zigzag design with the full flow though I was thinking of. Instead I'll have each pipe in parallel with drip emitters limiting flow to 2GPH per pipe (Can I double that?). I'm still planning on tilting the ladder 45° to the north, but now by also dropping one side by 2° (about 4" for 10' of pipe) to give the 40:1 drop I want. I also get about twice as many pipes in the same area this way, limited only by the minimum space I can put between 'T' fittings. On the inlet side I'll have caps with the drip emitters plumbed into each cap, on the outlet side I'll have the 'T's connected together to feed into return. If I can place the 4" pipes 6" apart on center then I can get 10 of them into the space I'll have. It means I'll have to have bigger grow beds than I'd originally planned on, to handle the excess water since the piping will only be using 20GPH of the ~600GPH total (also smaller than I'd thought because there's not as much water in the pipes). That will actually give me a more traditional design, with the grow beds doing most of the work and the NFT portion doing much less.

And here's as close as seem to be able to get to a Sketchup system drawing... :-)

I found a couple of headers that give me adjustable flow rates from 2GPH to 10GPH to feed each of the pipes. Six outlets each, I'll cap the extras. What's considered optimal for flow rates? 3m of 100mm pipes with 75mm holes drilled every 200mm. I get 14 plants per pipe and ten pipes. I'm going to need a scheme for providing filtered (just to have solid removed so the headers don't get clogged) pressurized water to them though, so maybe a separate pump just for them? Something that sits post-grow beds and pre-fish tanks?

I'm starting to lean on thinking of this as two systems with common fish tanks. The base is a typical system with the fish tanks feeding the grow beds which return to the fish tank and the secondary system takes water from after the grow beds and send it through all those lovely pipes...

I finally actually purchased something. Four of the pipes, two Ts, a 90° bend, a 45° bend and three end caps. That way I can assemble a minimal portion to figure out what my measurements really are. I also picked up two 10' 2x6s which I'll notch to hold each end of the pipes up. Both will be mounted 45° from horizontal, with one side (the one with the Ts and bends) 5-6" lower than the other.

I'm out on the road this week, but I'll try and put together pictures next week.

Goodday bill.. concerning the pump inlet being at the base.. what I see being a big problem is by chance a leak develop downstream the pump discharge... u stand a chance emptying your entire fish tank killing all your fishes.. I suggest not going lower than half way once your pump is taking suction from your fish tank..

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I think I'm going to re-spin the design with the fish tanks above ground. The potential goodness from holding the fish tanks at a more stable temperature are just outweighed by being able to put a sump lower than the rest of the system. It'll still look like two systems with a common sump and fish tanks. With a sump tank I don't need to put pumps in the fish tanks. The two sides then look like this:

1) 2 full size IBCs fish tanks gravity feed four half IBC grow beds which feed a filter that empties into the sump, where water is pumped back to the fish tanks. Filter design determines if the sump needs to be dug below grade or not. I'm not sure how I'll handle mixing the water from the two fish tanks together or if I'll keep them somewhat isolated. If I can find the room, I could expend to double the number of grow beds without overdoing the capacity, I think.

2) 10 10ft 4" pipes are provided water at about 2GPH each through a pressurized line. Each pipe is sloped to 1:40 (3" drop in 10') and holds 14 pots for plants. Water after passing through the pipes is routed back to the sump. The rack of pipes is designed with each pipe aligned above and behind the previous pipe at a 45 degree angle, to allow for maximum light. The fish tanks are placed below the rack of pipes and there's an opaque shade under the rack, shading the fish tanks from the sun.

I'll initially put the system together outside, on a raised, insulated deck, with plans to expand the deck into the floor of a greenhouse similar to this: