Backyard Aquaponics
A place to discuss aquaponics

Well, I never thought I would get to this point, but I now have some questions about my plants. I planted some yellow onions when I first set up the system. In the dirt garden, it would take most of the summer before they would go to seed. Well, after six weeks, they are starting to go to seed, and the bulb isn't even mature yet. They have HUGE root sets that are thick and kinky, whereas normally they are not so thick. I am having a similar problem with my raddishes. The green parts above the ground are growing WAY faster than the parts below the ground. Anyone have thoughts on what my problem might be?

I think you will find with the high nitreates, you will get a nice big leafy top and not much of a root. Carrots would most likely perform quite similarly. Any idea of how high your nitrates are?

Nitrates have been in the 20-30 range consistantly

i wouldn't say that was high

I have and am growing onions, but just harvest the greens. Never tried any other (root crop).
I wonder if they would produce better if once sprouted the water level of the grow bed is lowered slightly so that the produce has a dry spot to grow. This would have to be a dedicated grow bed so that the changing of water levels would not affect other plants.
Just thinking out loud.

Potassium!!!!!!!
Most root crops need enough potassium to be successful! Onions, potatoes, carrots etc. You might look into getting a fish safe potassium supplement for your system.
http://www.aquaticeco.com/subcategories/3429/Pond-Flourish

Would sea salt add enough potassium?

I'm becoming more and more convinced that all nutrient problems can be solved by viewing water as diluted sea water.

I kinda doubt sea salt would add enough potassium before the salt concentration got too high for the plants. However, perhaps salting with potassium chloride (instead of sodium chloride) might work though I have not gotten to test this myself yet.

There a glut of bananas here in Aust atm, because the cyclone knocked out the entire crop they year before, so they're ESPECIALLY cheap. I just bury what starts to get too brown in my GB and seem to have enough potassium from that, all the B vitamins

Hey KP, with or without the peels? Bananas are the most sprayed plant in the world, I wouldn't want the chemicals that coat the peels to get into the beds.

I did it peelless, yet the peels went into my compost bin...

I agree with TLC. Potassium is required. If the plants continue to over grow the leafy parts then cut back the amount of nitrogen by slowing feeding the fish. Using nitrogen to control your crops is an old hydroponics trick. You can cause rapid flowering or fruit finishing by dropping the nitrogen a bit low or you can make rapid plant growth using to much nitrogen.

Dan...
without starving our fish, have you any plans or ideas regarding controlling the nitrogen?
perhaps dual systems? 1 with fish and 1 without (barring the mosquito eaters)
or could you just slow the cycle time?


One thing that worked for me once, as I was getting very little growth, was harvesting ALL the duckweed off my ponds. This caused a large nitrate spike, from unreadable to about 4 I think.

Slowing the cycle time would not help - just end up with more ammonia.

OB, I meant for 1 bed only... so the other beds would get more (if the bacteria could handle it) and 1 would get less, but would they? continuous flow with autosiphons here...