500 Gallon Aquaponics System

These are the plans and design for the 4th version of the aquaponics system that we’ve made. It’s amazing how much is learned by simply creating aquaponics systems and testing them out.

What is Aquaponics

Basically, it’s a fish tank that lets you harvest the fish, and uses vegetables to clean up the tank.

1. Pump water to the fish
2. Aerate, circulate, separate solids
3. water falls by gravity to the plants
4. plants clean it, grow healthy, and return it to sump

Fresh organic fish and veggies grown year round in a small area, with 85% less water than normal farming.

How this Aquaponics System Works

A. Solar hot water heater (thermo siphon design). CPVC pipes on a 4×8 sheet of plywood, clear plastic (or glass) lid to trap the heat. Thermodynamics principles lets me put cold water in, and it will rise as hot water to the output. This needs about 2.5 gallons per minute flow. Too fast and it doesn’t work as intended, too slow and it will literally melt down. Heating water is about $100 a month if you use other methods. This cost about $150 to build. I could pump it through underground pipes to heat the entire greenhouse if needed, or to a rabbit hutch, etc. It’s hot water, about 180F (regulated by how fast water goes through it). I may need a way to mix it back with cold water before it hits the tanks. I might also need a separate pump instead of a valve to control pressure. If I were in too cold of a climate this wouldn’t work the same and I’d need additional heat.
B. Bypass valves for solar hot water heater in warm months. I can close the in/out and open the bypass and water will not go through the heater at all. Fish and plants need certain temperatures to reproduce, grow fast, fight disease, and keep metabolism up (eat and poop). Without these elements, the system grows slower or things die.
C. Backpressure valve for sump aerator. I have a large pump (2000 gallons per hour) in the sump. But I only need to pump about 500 gallons per hour for the purging of the tanks and bringining in clean water. I redirect the backpressure by adjusting this valve. Now my pump can just pump full time, which is better for it. turning a pump on and off reduces it’s life. Also, this backpressure is used to really blast air into the water. Traditional air stones only last a few months. Instead of buying new ones, I did this to aerate the water. Saves electricity, manufacturing, breakable parts, etc. If I need to, I can also spray this water into the air and let it fall further. this would allow me to cool the water. I don’t think this will be an issue, but it’s a simple modification to allow this. I’ll have a series of 1/4″ holes on a horizontal pipe to shoot jets all over into the sump and make sure there isn’t a solids build up. This aquaponics system design also allows me to regulate the speed at which the grow beds fill by limiting how much water goes into the system.
D. Sump pump on a float. 250 gallon tank of clean water, little to no solids. Gravity and cut off switch combined keep sump from overflowing or burning up. It won’t pump out more than it can take in if I adjust things properly and monitor it daily.
E. Sump pump aerator. Backpressure from the valve above allows some water to continue and some water to go through an aerator back into the sump. This makes it easy to use a larger pump and aerates water for fish before it even gets to them. It is hard to have too much oxygen in the water. All of these aerators help to off gas toxins too.
F. Drain back from grow beds should be clean as it is filtered many times, at least clean enough for fish to live in. Venturi process injects air for additional aeration with zero maintenance and pumps, using gravity to aerate water instead.
H. Bell siphon, one per grow bed. All of them drain back to sump tank (EDF area). A bell siphon is a device that autsiphons water out to the bottom once it reaches the top. No mechanical parts/motors, just physics and gravity. By using this I can flood beds and then drain them out repeatedly without pumps or timers. The natural fill and drain cycle is the timer, controlled by how fast water enters.
I. Grow beds. Gravel inside of a large trough lined with pond liner. You can have up to 2:1 ratio of water for the grow beds. So, if I had 2 IBC 270 gallon tanks of fish (540g total), I could support about 8 grow beds that are 8′ long x 2′ wide x 12″deep. The 12″ depth is important for many reasons. It keeps plants healthy by not rotting the roots, shades water so algae doesn’t grow (if water isn’t pumped too high before draining), and provides a stratification of the various elements of fish poop sludge for worms, oxygen and bacteria to clean the water and break down ammonia into nitrates/nitrites. This is a natural process that takes about 8 months to grow a full production bacteria colony. The plants in turn, eat up the nitrates, and you get clean water as a byproduct back to (F). I Need to make sure I can never get into a race condition where the beds are full, but the sump shuts off because it’s empty.
J. A valve to each grow bed allows me to control the flow, and thus how fast the tanks flood and drain. I can grow different types of plants this way because not all plants like the same amounts of water. Isolation of grow beds also isolates pests and allows me to only damage some of the crop if I’m infested. It gives me more time and ability to manage the crops.
K. This is a gravity fed drain that filters waste from the sand filter before it gets to my grow beds. This entire tank (LRK) is designed to mechanically separate solids (fish waste) so I have water that is easier for the worms and plants to break down and so that my pumps stay clean longer. If I don’t manually filter solids, I might fill up my grow beds with more sludge than they can process, and that would kill everything. By filtering solids like this, I also keep the valves healthy and clean. If they are not clean, I have to tweak them and purge them often as they clog up.
L. Sand filter. Gravity pours partially filtered water from the swirl filter into sand in a jar. This chews up and breaks up remaining solids before it goes on. Maintenance free, cheap, perfect. Eventually I have to replace sand and possibly the nozzle, but this is very low maintenance.
M. Swirl filter. Mechanical separation of fish waste. The tanks use a siphon (N) that has a T on it open to the air to prevent a complete siphon. Gravity pushes it through tanks and it sucks up the waste off of the bottom. The solids go into a cone where they settle to the bottom. I can then purge this portion every few days and have super rich fertilizer for regular dirt gardens. This is also a way to get the fish poop out of the system, allowing me to stock more fish than I should be able to. The input pipe is lower than the output pipe to help solids go down by gravity and swirl instead of up into the sand filter.
N. SLO is a system of siphoning water from the bottom (and thus getting the solids lifted). A “Tee” at the bend ensures that water doesn’t autosiphon out past a certain level. The pipe on the bottom is a 4 way T that has vents cut into it to keep fish from entering, and to spread out the area of available suction and help prevent dead spots.
O. Fish tanks. IBC containers, food grade 275 gallon each. More water means a more stable system from temperature chagnes, PH, etc. I’m also able to hold about 1 fish for every 2 gallons safely. I have chosen 2 tanks because a large one is 2x as expensive, but also because I can sort my stock. One tank could have full grown adults, ready to be harvested, and another tank could have smaller fish that might get eaten by the larger ones. I could also put a stack of pipes in and have 3 or 4 breeders for this tank. In addition, this design is highly modular. You can just keep adding tanks, growbeds (and eventually more sump space) as needed.
P. Hot water return. Hot water is expensive. This is fed from the solar heater array above. A clear section allows me to make sure it’s flowing, and not stagnant up top.
Q. Venturi snakes. This is my design/idea. I will inject air (via gravity) at the top and use a flexible hose at the bottom with a sprayer head. This should move around randomly in the tank disturbing the bottom and not allowing dead spots while at the same time aerating the entire tank. This would not be necessary if I had cone bottom tanks, but those cost about $400 -$700 each and IBC tanks are only $120 each, delivered. The pressure is regulated from the sump backpressure valve (C). I can control how fast water flows into the entire growbed system by adjusting (C), and I can individually control turbulence in each tank with (Q and R). Different aquaculture likes different amounts of water running through it.
R. Backup Aerator. In the event that my sump pump dies, the grow beds will drain and it will fill up. Plants are fine for a few days without water flowing, unless it’s 115F outside. However, fish will die within hours without aeration at any temp because of how dense the fish population will be. And within days or several hours without filtration of the ammonia. I’m not able to filter ammonia out, but I can purge as much solids as possible still because this pump moves things through the swirl filter and sand filter. Also, the down spouts will be under pressure as nozzles that spray into tank, or as venturi aerators. This gives me a chance to swap pumps in case of a single pump failure with much less danger to fish. Because it’s pumping mostly clean water (swirl filter + sand filter), this pump should require very little maintenance. Stopping one of the pumps for any reason (maintenance or emergency), still aerates the water.

Greenhouse

Everything is up on cinder blocks and 2×4 as needed to get the proper height. It will go inside of a greenhouse/shadehouse to regulate temperature and protect against pests (neighbors or cats have been getting trash into my yard, specifically in the aquaponics).
The greenhouse/shadehouse is designed to have clear plastic or shadecloth as needed, and a slightly raised gravel floor from the several tons of river rock I purchased for the front yard. We built it out of aluminum pipes lashed together and then anchored to a brick wall on one side and the ground on the other.
Care has to be taken that a hot day doesn’t suprise us and cook everything inside.

Water Cooling Methods

If needed, I could cool the water by pumping it down underground instead of above ground (thank you for the idea Mike).
A less labor intensive way that will work for me though is probably to keep the water shaded and insulated, and to spray the water into the air back into the sump for evaporative cooling. This evaporative cooling will cost quite a bit of water though, so if it was extremely hot for extended periods of time, the underground heat sink would be a perfect solution worth the effort. I haven’t researched it, but I imagine an array like the solar heater, but angled so hot water goes into the top and cold water flows down the sump would be what I want. Perhaps something simple like a snake back and forth through the earth would work too – I would just have to be careful of pipe resistance and make sure drain beds could drain fast enough.

Pricing

I suspect the entire system will be less than $2500 considering all parts, and the hired labor that I had help me build the greenhouse. I also think it will cut our grocery bill down to $100 a month total for electricity, stuff we can’t grow, and maintenance. In addition, it’s 100% organic, fresh, and healthy. I eventually want to sell the fish too for income and the entire project is a “business” so it will be a tax write off until it makes a profit. I found I out I need special permits to legally eat fish that I raise for myself (go figure). Here is a list of some of the components:

• $250 – 150 Tilapia fingerlings + Overnight shipping
• $360 – 3x Food Grade IBC tanks. 275 Gallon each, 250 gallon usuable.
• $300 – Sump Pump, 2000 GPH, 22′ lift, 1.5 amps
• $50 – Sump shut off switch
• $150 – estimate on PVC parts, gaskets, valves and glue where needed
• $150 – solar water heater parts, boards, pipes, glue, special caulk, glass
• $250 – Greenhouse parts, shadecloth, clear vinyl tarp
• $40 – Cinderblocks, Misc Lumber
• $160 – Firestone EPDM Pond Liner 45 Mil – 10 x 10 Feet
• $200 – Lumber for grow beds
• $20 – 55 gallon food grade barrel
• $35 – secondary pump
• $25 – pH, Ammonia, Nitrate Test Kits
• $100 – estimate on gravel
• $20 – clear vinyl tubing
• $250 – Labor to dig sump, posts, help build greenhouse
• $150 – Starter plants, seeds, seaweed extract, spray bottles, etc
• $??? – Government meddling, or right to exist taxes (licenses, fees, etc to eat tilapia)

That comes out to $2460 approximately before licenses.

Additional Things I’d Like….

• $300 – Backup, hot standby, Sump pump like first one
• $35 – backup, hot standby, Aerator pump like first one
• $750 – Off Grid Solar Array (2 panels, inverter, regulator, battery bank for overnight use)
• $150 – other aquaculture
• $200 – plants instead of seeds
• $350 – Backup generator and a week’s fuel … just in case

The efficient aquafarmer could spend another $1750 on things to prevent disasters and speed things along/add variety of crop. I bought the backup pump, and am investigating batteries and a hot standby switch, but solar is so expensive and it’s only for if zombies attack so I can’t really justify it.

Maintenance Costs

• As Needed – Estimate 1-4 days, purge swirl filter
• As Needed – trade or sell fish/veggies
• Daily – monitor water levels and temperature
• Daily – check plants for harvest, pests, health
• Daily – monitor fish while feeding, look for spots, damage, odd behavior, deaths
• Weekly – top off evaporated water ($5/month)
• Weekly – pH, Ammonia, Nitrate tests… as needed (10 minutes)
• Weekly – Sort stock by size, verify density
• Monthly – clean filters (20 minutes)
• Monthly – monitor and plan for upcoming crops based on weather changes (1-3 hours)
• Monthly – Water bill ($4-$5)
• Monthly – Electricity bill ($8 monthly, .95A/105W pump @ 10.5 per Kw/H 24×7)
• As Needed – Fish food can be grown, free, or purchased

Space Used

It all fits in a 6′ by 30′ space as designed, which is enough for just about any backyard in the US. I can fit 3 of these and still have a backyard – and I have a pretty small back yard.

Chickens and Rabbits

I also plan to have chickens (for eggs) and rabbits (for meat and to sell) inside this system. Their waste will drop into the tank and be processed just like the fish waste. This will add a variety of nutrients and minerals as the bacteria breaks it down and make clean up of the animals much easier while providing additional protein choices – that is still a way off though. I also need more planning, and probably more filtration (a second system). I’ll have to be careful to wash greens first if I do this.

Progress Pictures (updated frequently)

This is a 80″ by 30′ section.

We used 42 EMT 1/2″ conduit pipes to build the framework, 15 wall connectors and 15 female to female pipe connectors. The ends used a treated 4×4. Total cost in parts was about $120, but I paid someone $150 to put it together, so $270. The shade cloth is about $50, and the clear tarp for the winter was about $80. A small 8’x10′ greenhouse from harbor freight is almost $750 so this is a good savings I think, and much more versatile.

The river rock is left over and costs about $32 a ton. The pest guy happened to spray this part of my pile of river rock, so it became flooring instead. I have several more tons, but it still irritated me. You can see where the two IBC tanks will go. The current IBC will become a sump.

We used some of the plywood trimmings to make spacers. 2″x4″ @12′ are much cheaper than buying 12′ 4x4s I feel confident this can hold the weight of the grow beds. I might of been better to put the cross braces 16″ instead of 24″, we’ll see. I messed up a bit though and did things out of order. It would of been better to put the cross braces in first, then the spacers and second 2×4. We had to toenail them in instead of come in through the ends.

We put the 5/8 plywood down (again maybe 3/4 is needed?), then we built the side walls. I could of saved some money by getting scraps and cut offs from lowes/home depot, but I didn’t think of that until too late. Also, I could of saved a few dollars by using 92″ studs instead of 96″ as the cuts worked out to waste 4″. Each of the pieces is 9″, so it would of fit perfection to cut 10 of them out of a 92″ stud.

Side view of the grow bed.

Justin asked me if he could dig a hole when I told him I was going to hire someone to do it. He got about half way down into the clay but his hands got blisters (through the gloves), so I made him stop. He helped me with all of the other assembly, measuring, cutting, etc. We had fun, I think lol.

Finished grow bed, before it is placed on the 4×4 posts. The posts will go every 2 feet and raise the grow bed about 28″ off of the ground. The 2x4s on top are to keep the sides from flexing outwards from the weight of the grow media and water.

It took about a day to measure, cut, assemble 1 complete grow bed, and measure and cut the parts for the other grow bed. I think it will take about 4 hours or so to assemble it, but I’ll save that for next week.