Aquaponic system doesn't grow the plants

Question

I have created aquaponic system and tried to plant tomatoes, cucumbers and some other herbs. They sprout without problem but after couple of days they dried out. I tried it 2 times with the same result.

The water circulates 15 min every hour. I'm not using siphon setup but water flow one. At the bottom I have a gravel to filter it and at the top I use clay pellets in which I seeded the seeds.

The white drain pipe goes up to where the clay pellets and the gravel meets. So the seeds are not constantly in the water but absorb the moisture from the pellets. Any idea how to make it work? I'm planning to give up and just to plant some flowers meant for ponds.

Answer 1

(This is only meant as an extended comment. I hope someone with aquaponics experience will be able to answer your question. I have only seen much bigger aquaponics set-ups, outside.)

I unfortunately don't have any experience with aquaponics, but it looks like your system is inside. My experience with tomatoes is that they need lots of warmth and light. My tomatoes I grow at 30 ºC outside in the sun. On top of that I've been told that tomatoes get sweeter with less water, so I only water them once a day. (I think that cucumbers (like melons), also need light and warmth, and depending on your herbs, they, too might need light and warmth.)

So, I think that a problem with your setup might be not enough sunlight. (Seeds do sprout without sunlight, but as soon as they produce leaves, they need enough light to grow larger.)

Answer 2

You didn't mention if you had done any Ph readings, so it seems like a good to consider the ph balancing process that aquaponic systems are known for, there is a ph plummet issue which can happen as a new system balances. It seems that my fish are living in 8.0 water after the winter ice melted, so I"m trying to keep it down toward 6.5

Answer 3

If your system does not flood and drain somehow, it is to be expected that the plants will dry out. Without the flood and drain, the plants will have a hard time getting their roots all the way to the water.

You can accomplish a flood and drain via two methods:

1. Use a timer on the pump and use a standard 2-outlet setup like in a hydro tray. One short stand pipe to set a low water level and a second taller stand pipe to set a high water level. The low level should be at most 1 " above the floor of the grow tray. Make the high level about 1-2 inches below the surface of your media. The pump is on for 5-10 minutes then off for 5-10 minutes.

2. Use a standard bell siphon (check out Affnan's site for the industry standard). The siphon can take some serious fidgeting to get working properly but once its going, it is a lovely piece of tech. The autosiphon design will automatically drain your plant bed of water automatically once it hits a certain level and then automatically shut off once the bed is empty. We use the bell siphon for our media beds every time. They take extra fine tuning but the benefits are totally worth it.

Hope this helps!

Answer 4

I had the same system with the same result as yours; my lettuce seeds germinated but later all the plants wilted.

My suggestion, and what I have done in my system, is just let the grow-bed "mature" -- let the water cycle for a week. The reason might be that the water may not have enough nutrients for it to grow and support plants. Try cycling, continually flooding and draining, or just let water flow continuously to your grow-bed for few days.

By doing it, your grow bed will be colonized with different bacteria (and micro-fauna when the system is older) that are responsible for the conversion of fish waste. As they consume the fish waste they turn it into nutrients that the plants need to thrive.

Here's an illustration of the nitrogen cycle for reference:

Answer 5

Had the same problem... no air in the clay bed. Add an additional air stone to the clay bed. I also devised a filtration system so solid waste wouldn't be in the clay bed and leave the "fishy" smell in my home or whatever area you have your system in.