Daily Operation of My Aquaponics System
When it comes to the daily operations of an aquaponics system there is very little to do. However, it is a far cry from being a “maintenance free” or “hands off” operation by any stretch of the imagination. Since I am working a full time job during the week, I usually attend to the required maintenance tasks on the weekend, which is sufficient.
Watering Plants
Luckily, this task is rather automated in an aquaponics system. I have a submersible pond pump in my pond. The pump is connected to a timer. My current watering schedule is set to flooding the grow bed every three hours 24/7. I designed my system a bit different from the typical aquaponics grow beds out there. Mine does not have a bell siphon to drain the bed when it has reached the desired fill level. I purely control this via the on-time of the pump. In the beginning I timed how long the pump takes to fill the bed right below my overflow pipe, which is mounted in the middle of the grow bed. It took 16 minutes, if I remember correctly. Hence, I programmed the timer to come on every three hours for 16 minutes. Once the pump turns off, the water in the grow bed drains back through the pump and the connected hose into the pond. This pump has a foam filter on the inlet to prevent sludge and solid fish waster and other solids to reach the grow bed. Theoretically, the foam filter is getting back washed when the pump turns off, which reduces the maintenance task of having to clean the filter. In fact, I have not had to clean that filter since I installed it about 5 months ago or so. It is still working just fine. Every now and then I check to make sure that the fill level still reaches the desired point to make sure that I am not having any issues. I am happy with this design so far.
Feeding the Fish
About five months ago, I picked up a bucket full of Tilapia fingerlings from a local farmer. He gave me about 50 fish in different sizes, from 1″ to 3″. Back then I had a small, automated fish feeder. However, that one can’t keep up with the demands of the fish. The larger ones have grown to 12″ to 14″ and are quite hungry. I have switched to hand feeding them until I get a larger fish feeder. I typically feed them once the in the morning only during the week. On the weekends, I feed them two or three times a day. I am not in a great hurry to grow them as fast as possible.
Video of feeding the Mozambique Tilapia. Some look like gold fish, the darker ones are harder to see. The water is actually adding to the orange color due to the added iron in the system, which makes the water a ruby red color.
Topping off Water
Typically, I have to add or top off water every weekend. About 25 gallons. My tank is 250 gallons, so there is about a 10% loss per week. The system is in Southern California on the outskirts of the Mojave Desert. Hence, the air is bone dry and it is hot. I assume that most of the loss is due to evaporation with the remainder contributed to whatever the plants take up. My grow bed is rather crowded at the moment. I keep adding vitamin C powder into my top off water in order to remove the chlorine. I don’t want to upset my biochemistry with chemical de-chlorination. After all, I would like to eat the food that I am growing.
Maintaining Water Temperature
Tilapia need at least about 70 degrees F. Although I had them in 63F for a while without any fatalities. My first design had two aquarium heaters with 300W each. I got them from some online discount store located in China. 2 x 300W = 600W. However, here in Southern California, the night temperatures dropped to around 34F at which point the heaters could not keep up with the temperature swings anymore. My fish became extremely sluggish and wouldn’t eat anymore. I added a third heater for a total of 900W. This was only a marginal improvement. Then a couple of weeks later, the water temperature dropped again into the low 60’s and I got worried about the well being of my inhabitants. I actually designed my own 1,500W water heating system with a circulation pump. I will cover this in another post in detail. This latest design works rock solid and I can set whatever temperature I like. I currently keep the fish at 75F and they seem to be happy. You can always tell by how aggressively they feed. There is a lot of splashing going on come feeding time. I could keep them at higher temperatures, but I don’t want to pay too much for my electric bill either. So, this seems to be a good compromise for now.
Nutrients & Fertilizer
During the initial start-up of the system, I had a lot of trouble with the water chemistry. The fish and the plants were noticeably stressed for a while until I got the hang of it. One lesson learned with respect to plant health is, you absolutely need to add iron. I am adding chelated iron every 3 weeks. I went without adding it for 4-5 weeks and plant growth comes to a complete halt and leaves turn weak and yellow. I will also cover this in more detail in an upcoming post. The effects of having the proper iron levels are quite dramatic and so are the effects of an iron deficiency.
Picking Pests
My system got invaded by all kinds of bugs. You really have to fight for your food. It started with Mealy Worms, Aphids and then Caterpillars. I make it a habit to pick caterpillars and feed them to the fish. For the mealy worms and aphids I released about a few hundred lady bugs and they went to town on these little buggers.