Backyard Aquaponics
A place to discuss aquaponics

Greetings, a couple of weeks ago I began construction on an Aquaponics system in the back yard of my home in Hill Country in Texas. I live just outside of Austin. The fish tank is the reason that I named this "Project Insanity." Wait for it and you will understand. First lets go over the design plan.



In this picture you can see the concept for the fish tank integrated with the new patio. The patio will be a raised paver patio (possibly flagstone) where the side walls are made out of standard cinderblock mortared to a 4" concrete foundation. At various points in the mortar, there will be small tubes placed as weep holes to prevent water back pressure in the patio. On top of the cinderblock will be the capstones which will be of the same stone as the rest of the patio. On all visible sides will be mortared thin veneer facing stone. In the image above the ground level is at the top of the first row of patio cinderblocks.

The fish tank is a 5' deep, 19' long, 5' wide pond. The pond is set deep in the ground and raised above the patio by 20 inches which will allow one to sit on the side of the wall and feed the fish or just watch them. The pond will be open to the sun but that is ok, I have considered algae and I will get to that later. You will note that the retaining wall of the patio will not be mortared to the pond. Since they are on different foundations connecting them could lead to cracking. The base of the pond will contain a footing for the cinderblock walls as well as a bottom drain from which to pull water in the pond.

What is not shown in this sketchup file is the filter pit. That will take some 2' of the pond at the far corner of the patio away from the house I will talk about that later.

If you want to design you own version of this it is important that you plan it first before digging first. Trying to cut cinderblock to fit odd lengths is a tough challenge. let the cinderblock dictate exact dimensions to minimize cutting. I will only need to cut cinderblocks on the long wall of the patio. I have to put in that corner because its my black lab's personal spot and I cant leave him out.

The pond will be connected to the aquaponics system with a series of systems. From the bottom of the pond a drain will go to a vertical stand pipe in a large container like a 30 or 50 gallon drum. The water will be pushed into this solids filter by hydrostatic pressure from the pond. The top of the drum will be at the same height as the top of the pond. The drum will have an outlet about 3/4 of the way up the drum and down to another identical solids filter. However the outlet to that will go to a pump that will pull water out of the drum and send the water to the gravel media beds. The gravel beds will drain by bell siphon into a pipe that will return to a solids filter that leads to a traditional Koi Pond filter, through UV filter and then get pumped up to a Weir that will waterfall back into the tank. I may also introduce one or more raft beds and airstone aeration.

The algae will be controlled by starvation. Any filtering not accomplished by the grow beds will be handled by the Koi Pond filter and then water clarity by the UV filter. The algae will have little to feed on. With the pump turning over the entire 3000 gallons twice per hour, nitrates will have a tough time forming in the pool to any serious degree. Although there will be some algae for sure, it wont represent that much of a problem.

Beginning Excavation a couple of weeks ago and we will soon see why it is called Project insanity. We are excavating the trenches for the wall. The fill dirt from the pond excavation will go into the patio. We will ultimately tamp that down, use roadbase to fill it up to 2" from the top then sand and rock.



The kids are getting involved and even the dog.

And at the end of Day two we have started on the pond excavation:



We have hit bedrock. Here I put in a sledge hammer to show the depth of the trench. Under that is what amounts to solid bedrock.



After this we got rained out for a week. Pouring torrential rains and then a mud bath to please the most discerning pig. After that we got to work again. We removed the conduit and sprinkler lines in the area and finished the excavation of the pond area as much as we can with a shovel and pic. You can see my little contractors putting on the final touches.



Now the pond isnt nearly deep enough. I need at least 3.5 feet below ground. However there is a problem. This video should show you what I mean.

Digging Further

Hmm. Now we need a jackhammer to go further. In the meantime I will start working on the trenches for the patio, cleaning them up and making them to depth.

Stay tuned, more to come. All comments and suggestions welcome.

you have obviously put a lot of thought into this design and i look forward to seeing how it turns out. You must not have the black clay soil we have in dallas because i cant imaging digging a 3'x19' hole in my yard by hand.

i calc 3500 gallon fish tank at 228"x60"x60" unless you are talking about the whole footprint of the tank where we must removed 8" cinderblock widthx2 and 8"x2 length which would set it at 2400 gallons?

I am not picturing where or how many grow beds you are planning on putting in there but i think maybe you settling tank is going to limit the volume of grow beds you can flood and drain. A 55 gallon barrel is about 27" tall. if you put the stand pipe and the midway point that gives you about 13 inches of rise and fall flexibility. 228"x60"x13" is about 770 gallons assuming the tank is completely full. 770 gallons can probably flood and drain ~1400 gallons of the average media types, again assuming the tank is completely full.. In the hottest summer months you can lose up to 3% water (~100 gallons) a day from evaporation and transpiration. (i average 15-20% a week from late june til sept). so you will have to keep the tank topped off daily to reach your grow bed potential. Obviously that can be circumvented with some or all grow beds constant flood. Just pointing this out. It sounds like you may be doing this more for the aquaculture than the vegetative growth which is fine. I tend to think the other way around so maybe my concerns dont apply to you.



I think you are over concerned about algae growth. I run 1500 gallons of fish tanks and i have an algae bloom about once every year that last for a couple of weeks then dies out and is then subdued by a naturally occurring enzyme for the rest of the year. The water quality is otherwise very clear and good. My only filtration is mt grow beds and i maybe turn my tank over once an hour.. maybe not quite once an hour, but i dont keep a high fish load. Is the koi filter solely for the purpose of algae control? or do you need more filtration because you are going to have a small mass of grow beds?


Again, neat project, please dont take anything i said as criticism, just academic. i always like to read and understand large backyard style builds with alternative materials. If you have seen one ibc/blue barrels build you have seen them all.

Ahh if only it were clay. Look at the video. It goes down 6 to 18 inches then solid limestone. I will need a jackhammer to finish it.



The dimensions I gave were approximate inside dimension of the tank so your calculation seems right.



Hmm you do have a point. I might be better off with one tall long tank than something like a 55 gallon drum. I suppose I could weld together two drums to give a larger height to the filters. I had already planned on connecting a solids rated pump in the bottom of the settling tank to be able to flush the tank. I have heard recommendations of a float valve activation in addition to the manual activation so that any torrential rain doesn't flood the system. I could make the settling tank out of the same block if I wanted to by simply partitioning the pond area to a small area that contains the settling tank so it would be of the same construction as the pond. However I do have to account for overflow and water in transit. I had debated putting a large underground rainwater cache / sump tank in the yard near the pond. I am going to have to do some more calculations on this.

As for grow beds, I didn't enumerate them in the original post. They will be a bit further away from the pond in the corner of my yard. I will build them also of concrete block. The pond when completed should be 3'3" above ground and if I can get my grow beds a foot or two lower than the top of the pond, I would be able to use gravity to feed the garden beds and then get away with a single pump from sump to weir. I had also planned on having one or more raft beds for lettuce production.

However I do want the ability to be able to maintain the system in the winter so a shut off to the garden beds that allows me to just use the standard pond filter would be a good thing. The pond should be more than sufficient to overwinter fish.



Good to hear about algae. The filtration is basically because I want the pond to be ornamental as well as functional and I also want to be able to shut off the flow to the garden beds in the circumstance that I need to do that. I would like the fish to have as good of an environment as possible so that they are as healthy as possible. If the gardens are shut off because it is freezing outside then I want the fish to still flourish.



Oh my, Please do continue to critique. Better now than later when I have it all installed. I am talking about this pond on Koiphen as well because there is so much expertise there. (I am wondering if I can keep Koi with food fish also). Id rather be corrected with you guys' superior knowledge.

The one thing that concerns me now is jumping fish. I don't want to put a net over the pond for aesthetics but I don't want my fish on the patio either.

when freezes come through i just turn off the pump. The cold temps slow the fish metabolism. They dont eat and they dont muck up the water. Cold water holds more oxygen that warm/hot water. I dont usually keep air stones on during the winter but i think i will start. I have a fish kill thread from last winter that can show you the worst case scenario, but my ibcs were much smaller water volume, they were completely above ground and that was the coldest, longest lasting cold front i have seen in 5 years. It was my first aquaponic fish kill.

your 3500 gallon fish tank being mostly underground gives you a lot of advantages. You can treat it more link a pond than a fish tank.
1) it is well insulated by the earth.
2) assuming light stocking density, the top of the tank could freeze over for probably a few weeks without any unusual fish stress or casualties
3) Aeration such as an air pump can bring the warm water from the bottom to the top and help keep the tank from freezing over at all.

In the hill country i bet you only rarely even get freezing temps for a wwek.. usually we get cold fronts that last 2-3 days then back up to mid 40's or low 50's


brian

Nice plan. I wish I could have an outdoor system but my winters falls and springs are much too harsh.

Are you sealing your concrete tanks and grow beds or using a liner? What type of liner or sealant do you have planned?

I have gold fish with my Tilapia and they get along just fine. Koi shouldn't be much different.

I havent forgotten about the thread but there have been two problems. Rain turned the site into a mud pile then after that we have the typical austin heat, upper 90s means heatstroke if you dig. So I have to wait for some cooler days when it doesnt rain.

Upper 90's ia a cool day in Kalgoorlie, it topped out at 115deg last year at one stage.