Aquaponics in my home

I will be putting a 70 gallon (230 liter?) aquarium in my living room. I will slowly stock it with juvenille fish and let grow big together - major point us that the initial bioload will be low.  I would like to put two shelves over the aquarium and put 4 house plants on each shelf. They will most likely be spider plants and will also start out as clippings. They will all be grown hydroponically, without any soil.  I would like to circulate the water from the aquarium into the plants but I dont know how to calculate the balance so that the water is kept clean and the plants have enough nutrients. Any suggestions?

Awesome! That's something I've always wanted to try.

I'm sure that you could do an analysis of everything and calculate it out, but in all the reading I've done about aquaria, I haven't seen home aquarium keepers doing elaborate analysis for freshwater tanks like that: trying to determine what plants will take out would be very complicated. Add to it two additional factors and things get even more complicated: 1) you'll need some sort of mechanical filtration to remove fish doo and other gunk; over time, the media for that will become home to bacteria that eat waste chemicals; 2) the gravel (or whatever) substrate is going to become home to those bacteria, too. At the same time, your fish will be growing, then stopping growth, then some will die, you'll get new ones. And so on.

End result: A very very very complicated thing to figure, probably something that takes a lot of technical knowledge to do, and it will still need to be adjusted over time.

I think you should go slowly and test as you go.

Basic aquarium tests can for the primary things you need to watch for -- nitrites, nitrates, etc. -- are not expensive. I think you should do what you're planning and just test on a very regular basis. If levels get too high, you can always insert a sponge or a gravel section or something in your water flow to host bacteria and clear your water. You can add plants, etc., too. As long as you start with a low bioload, as you've mentioned, and grow it slowly, you and your fish will be fine. A well planted tank can handle a fair bioload without additional filtration (though if the plants are submerged they may need extra carbon dioxide to flourish) and a low bioload with some sort of filtration will not go out of wack quickly under most circumstances. As long as you're careful, you won't harm your fish.

Please do post pictures and write about your experience -- I'm really curious about this.

Thanks. I am coming to the same conclusion. There may be a critical mass - number of gallons of water - before this can be a viable option.  I may just poure the water i take from the tank when making water changes and put in with the hydroponics mix.

I'd say go for it. The "Critical Mass" issue is really of no issue at all. Planted tanks are popular for this same reason. More plants, less filtration/maintenance that is needed.
There will be a equilibrium but there will be some experimenting to do to find it. For instance, if you use only spider planes and pathos only, they are not heavy feeders. They about survive forever in tap water and not much else. Plant something that fruits and or flowers and they will require more food. (i.e. strawberries, tomatoes)
Also the bacteria in the substrate will eat up some of the plant food. It will try to always achieve the equilibrium. If this does not leave enough for the plants just get rid of the substrate. That will also make cleaning easier.
Good luck. And post some pics to keep us updated. I'd love​ to see how this comes out.

Hello, I keep two aquariums (20 and 55) that are heavily planted and I may be a bit overstocked (corydoras keep breeding), I don’t have a set aquaponic system in place but I try to do my water changes weekly and use the water that I take out (vacuum my substrate, remove pest snails, extra plants, etc) and I irrigated my plants by hand... it is winter after all; and the biggest change I have seen is the amount of flowers that my lemon treen put out, it has been flowering not stop for the past 4 weeks!!! The aroma is heavenly... I don’t expect too many lemons... no pollinators inside the house. I bet if I keep it up next year I’ll have a great lemon year 😊

I have not done this. However, I have seen enormous marijuana grows that use fish in their hydroponic set ups. I know that there are several books and net articles on setting these systems up. If people can use it to grow weed I don’t see any reason it wouldn’t work for other plants. Good luck!

https://herb.co/2016/03/03/how-fish-help-you-grow-better-weed/

I had a 200 gal tank that housed dozens of cichlids.  I custom-built a cabinet to sit on top of the tank.  The top 6" of the cabinet was sectioned off and I installed a pond liner.  I placed several rafts with net pots in the water.  Above this was a PVC framework with grow lights.  My filtration system would pull from the fish tank and pump it up to the top area.  From there, it would gravity drain back to the fish tank.  The filter would do a good job of preventing too much mulm buildup in the growing area while still passing on the dissolved nutrients to the plants.  I was able to successfully grow lots of smaller plants like herbs.

I response to your question on how to balance the nutrients, I would say that it is nearly impossible.  There are so many nutrients to be balanced that it would take too much time, energy, and cost.  You can easily test for things like nitrate (or nitrite) and phosphate, but testing for potassium with any accuracy is much more costly.  And what about all of the micro nutrients that the plants (and fish) need? What about the contaminants that slowly build up over time and that we DON'T normally test for?  I'm a chemist, so testing and analysis is something that I love to do. I have access to a fully-equipped lab, yet it would take me several hours to perform all of the testing for the items that I know about.  But eventually, it is the things that I don't know about and don't test for that are going to cause me problems.  

For my system, once the nitrates or phosphates rose above a certain level, I would plan on doing a water change.  It kept the contaminants in check and allowed me to enjoy my system rather than overthink it.  

Rosa Elena Rivera wrote:Hello, I keep two aquariums (20 and 55) that are heavily planted and I may be a bit overstocked (corydoras keep breeding), I don’t have a set aquaponic system in place but I try to do my water changes weekly and use the water that I take out (vacuum my substrate, remove pest snails, extra plants, etc) and I irrigated my plants by hand... it is winter after all; and the biggest change I have seen is the amount of flowers that my lemon treen put out, it has been flowering not stop for the past 4 weeks!!! The aroma is heavenly... I don’t expect too many lemons... no pollinators inside the house. I bet if I keep it up next year I’ll have a great lemon year 😊

Rosa,  I pollinate my lemon tree in the house with a Q tip.  Works great!

If the plants in this system are in media ( like rocks or clay media) and you're using a ebb & flow type system (fill with water, then drain, repeat), you can put redworms (composting worms) in, & they'll eat up much of the accumulated residue.
If you instead, have the plants 'floating' in water, you can use mosquitofish in that water to eat up the sludge & dead roots that accumulate.  A plus is that they will also eat any mosquito larvae, and you don't have to feed them.

Rosa Elena Rivera wrote:I don’t have a set aquaponic system in place but I try to do my water changes weekly and use the water that I take out (vacuum my substrate, remove pest snails, extra plants, etc) and I irrigated my plants by hand...

I call this lazy aquaponics! My husband has a bunch of fishtanks and ponds, and I have him save the fish water from his water changes and I use it to water our garden. I have to water it anyway, and this way I'm watering it AND fertlizing it at the same time!

I will be putting a 70 gallon (230 liter?) aquarium in my living room. I will slowly stock it with juvenille fish and let grow big together - major point us that the initial bioload will be low.  I would like to put two shelves over the aquarium and put 4 house plants on each shelf. They will most likely be spider plants and will also start out as clippings. They will all be grown hydroponically, without any soil.  I would like to circulate the water from the aquarium into the plants but I dont know how to calculate the balance so that the water is kept clean and the plants have enough nutrients. Any suggestions?

Good job starting with a large tank with few fish! That should help with the nitrogen cycle. If you want to jump-start that cycle, and you have access to someone else's cycled tank, you can squeeze their filter into a bag or bucket and then pour that water into you tank. That should help inoculate your tank with the microrganisms that process the nitrogen.

I don't think you need to worry about the spiderplants and nutrient levels. Spider plants are pretty resilient and should do fine.

Tom Connolly wrote:I will be putting a 70 gallon (230 liter?) aquarium in my living room. I will slowly stock it with juvenille fish and let grow big together - major point us that the initial bioload will be low.  I would like to put two shelves over the aquarium and put 4 house plants on each shelf. They will most likely be spider plants and will also start out as clippings. They will all be grown hydroponically, without any soil.  I would like to circulate the water from the aquarium into the plants but I dont know how to calculate the balance so that the water is kept clean and the plants have enough nutrients. Any suggestions?

Dear Tom, buy an el cheapo EC-meter (roundabout 50-100$) and monitor your aquarium water. Keep EC (in mS / micro-Siemens) between 1.0 and 2.0. Below 1.0 your plants may start to starve. Above 2.0 your fish will start to suffer. Buy a cheap hand held pH-meter and keep your pH between 6.0 and 7.0. pH should slowly go down over time. Bring it back up with Calcium Carbonate (Marble, egshells) or Potassium Hydroxide (please be careful).

Buy nitrite "stickies", for example from Merck. Check weekly.

Don't panic when EC is too low or when pH goes below 6.0 or above 7.0. Simply engage in counter measures like water exchange or bringing the pH down.

Add a little bit of liquid iron chelate every now and then. It is available in small quantities in aquarium shops. But there it is very expensive. It becomes much more reasonably priced in larger quantities. I'm buying 30L for roundabout 100€.

In general: You can manage your system with an EC-meter and a pH-meter and some carful observation.