a system of aquaculture in which the waste produced by farmed fish or other aquatic animals supplies nutrients for plants grown hydroponically, which in turn purify the water.

Aquaponics @ CRT Labs

The Grove aquaponics set-up for CRT Labs, with kale above and goldfish in the tank.


If you’ve been by the lab over the last year or so, you’ve most likely seen our aquaponics systems. Filled with fish, ghost shrimp, herbs and vegetables, these systems work based on a symbiotic relationship between the aquatic life and the plants growing above. It’s a complex relationship based around the nitrogen cycle.

It’s great having living systems in your office space, but creates an interesting challenge when those living things rely on a small group of individuals that work remotely, travel constantly and in general have a very inconsistent office schedule. Aquaponics systems also have a decent amount of maintenance. More than once we’ve come back to the office after a weekend to find the water reservoirs empty, plants wilting and some very murky water. 

Ironically, for being a R&D technology lab we’ve come up with a decidedly low-tech solution: an Aquaponics Chores spreadsheet. The idea being that anyone can quickly scan the sheet that is taped next to each unit and see what needs to be done that day, and who did the previous day/week/month chores. We’ve broken tasks into 3 sections: Daily, Weekly and Monthly. I want to go over each task and give a little more detail on how it helps keep our aquaponics systems as productive as possible. It also helps spread the knowledge to other members of the lab besides myself, and combats the Bus factor.

Aquaponics Chores

Aquaponics Chore Chart, recently implemented by the labs


  • Feeding
    • Our aquatic friends require sustenance to survive, and this is also the only “input” into the system. To have a truly organic system, you need to use organic fish feed.
  • Water Levels
    • Correct water levels are crucial for optimal pump operation. Low water can also stress the fish, causing shortened lives, disease and eating issues.
  • Pumps are running
    • Just as crucial to feeding the fish is making sure the pumps are running, and not just running, but actually moving water. The only filtration in the system are the plant roots themselves, the fish can quickly die if this part of the nitrogen cycle stops working as nitrite is highly toxic to fish, as is ammonia.
  • Lights are on
    • Plants need light!
  • No dead animals
    • Besides being gross and unsightly, decomposing organic matter can add additional load to the plant root filtration system, sometimes more then your plants can handle.


  • Tank scrub
    • Algae will undoubtedly start forming on the aquarium walls, besides hiding your pretty fish, the algae also extracts nutrients from the water that would otherwise go to your delicious veggies and herbs.
  • PH levels
    • Optimal PH levels are low 7’s, plants prefer slightly more acidic levels, in the low 6’s to high 5’s while the fish and bacteria prefer slightly more alkaline in the high 7’s to low 8’s. So it’s a constant compromise to keep the 2 systems in check. Although once a system has been running for a while the PH levels become very stable, unless there are unforeseen inputs into the system.
  • Nitrgoen levels
    • Since the whole system relies on the nitrogen cycle working efficiently, it’s important to check nitrate, nitrite and ammonia levels to ensure the system is operating correctly.
  • Plant pruning
    • Once the system is up and running, plants should grow quite vigorously. Weekly pruning helps keep the plants in check and also provides fresh herbs and greens for the kitchen.


  • Filter Cleaning
    • I mentioned before that the only filtration in our aquaponics system are the plant roots themselves, this isn’t totally true. The pumps themselves have small filters to keep out large debris that may clog the pump and/or irrigation lines. It’s important to keep these clear for maximum water movement.
  • 25% Water change
    • This isn’t always necessary depending on how often you’re topping off the system, when plants are growing and/or humidity is very low. You may be topping the system off every few days, which is equivalent to 25% water changes every month. It helps keep the water “fresh” so you don’t get to much build up of any one nitrogen process.

We’ve just introduced the task sheet to the lab, and haven’t had much travel/absences yet, but hopefully this will help others understand the requirements of the system as well as keep our fish and plants as happy as possible. If it works out, maybe we’ll “appify” the process and open it up to other aquaponic farmers :). If you have any questions at all about aquaponics, hydroponics or other cool urban agriculture systems feel free to drop us a line.