Aquaponics tank N02 and N03 went high

[Lightnin]

I'm running a fishless cycle on a new tank that I am going to use for some aquaponics experiments. It's going to pump water from the tank into several hydroponic planters.

I noticed that as soon as I put my first hydroponic planter into the system, both Nitrates and Nitrites went very high (added plant on 8/29). I have two guesses: 1) I didn't rinse off the roots of the plant I planted (from my yard) and the little bit of soil had a lot of nitrates / nitrites, or 2) the Dehner 392035 Plant Clay 10 Litres Grain Size 8 mm / 16 mm.

I have nitrates / nitrites in them and poisoned the tank. Any ideas?


Many Thanks for any advice!













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[Autumnsky]

Are you familiar with the nitrification cycle?

Plants and fertilizers would have ammonia which would change to eventually be nitrites and nitrates.

Did you have any decaying plant mater in the soil like compost, fertilizers?

Did you soak or rinse the clay balls?

[Lightnin]

Thanks for the answer.
Yes, I'm familiar with the nitrogen cycle (see link to the google doc showing cycle data above). The ceramic balls were thoroughly rinsed before being placed in the system.


The bottom of the tank has growth medium, in which 3 aquarium plants are growing.



The NO2 and NO3 levels both jumped dramatically at the time that I added the hyroponics to the system. I could see the NO2 going high at that time, because I'd been feeding the tank Ammonia for about a week and the Ammonia levels went down around then. But the jump NO3 is harder to explain.

[King Fisher]

I could be wrong, and maybe you were getting at this point, but it sounds like your tank isn't cycled and is mid cycle. You dosed ammonia and now you're getting nitrites and nitrates. Spikes in nitrites and nitrates are common during a cycle so I'm guessing in time you will see the nitrites convert to nitrates. What's your ammonia level? Even if you had nitrites and nitrates in your plant roots before adding them to the tank I'd assume nitrites would eventually be cycled out once your beneficial bacteria grows in the tank. Water changes would remove the nitrates.

[Lightnin]

Thanks, both.


Yes - the thing that surprises me is that the nitrates and nitrites both went high on the same day I added the aquaponics plant / ceramic beads.

You can see a chart of their values here.


I can imagine that the nitrites would go high on that day - but both? They were both at high levels ever since, even after water changes. (Though a 2/3 water change yesterday did bring the nitrates down, finally.)

[Autumnsky]

Often the amount of ammonia is surprising in additive/substrate materials. As ammonia acts as a plant fertilizer which is helpful for plant growth, and starting a fishless cycle in a tank, it will cause a non cycled container/tank to spike.

Conditions like temp and PH, kH, can effect water changes. Did you use any water conditioners in the system? Also may have an effect on how it processes.

[King Fisher]

You may try 20 to 25% daily water changes for a week or two. Dose your ammonia after each water change if it gets really low or non existent. If you continue to get off the charts nitrites and nitrates try a couple large water changes in a day. Give about 6 hours or more between the water changes. Once it's lowered then dose ammonia again around 2-4ppm. Now, there is conflicting info on this. Some people say leave the tank alone even if your nitrites and nitrates are off the charts, letting the tank do it's thing. Ive never done this method so I don't have much reason to justify it. Hope this helps bud.

[Lightnin]

Thanks, all. My NO2 seems to be under control now. I did an experiment - getting my water down to a reasonable level of NO3 before adding the ceramic beads / planter back in to the circuit (without any plants). The levels stayed the same. So it seems likely that the cause of my earlier NO2 and NO3 spike was not cleaning the dirt off the roots of the small plant I put into the system well enough. In a couple of days I'll plant some mint (after rinsing the roots well), and see what that does to the levels.