A spin on fishless cycling

[aquamanis]

After reading an article about cycling without fish but using lots of plants, I wondered if the ammonia could be added in the form of nitrogen fertilizer for the plants? (like hydroponic fertilizer). I,ve read that nitrogen will get converted to ammonia which is the plants prefered food. You could cycle using nitrogen fertilizer for a few weeks then do a big water change to rid any excess nitrogen before introducing fish. Of course all water parameters will have to be monitored as normal to see when the cycle has finished. What do you think?

 

[Alien Anna]

The point of adding the ammonia is not for the plants but for the beneficial bacteria that you need to grow to turn ammonia into nitrite (and then the beneficial bacteria that turn nitrite into nitrate). If you just add nitrates you're not growing those beneficial bacteria.

 

[aquamanis]

Hi Anna, I know the bacteria needs the ammonia to survive. The point I was getting at is nitrogen is supposed to be converted to ammonia, this is what happens in the garden. The actual nitrogen is not used by the plant untill its converted to ammonia and nitrate so why cant you use nitrogen to feed both plants and bacteria at the same time?

 

[aquamanis]

I,m going to do an experiment when I get home tonight. I,m going to put some nitrogen rich fertilizer in a 10lt container with a plant. I,ll measure the ammonia, nitrite and nitrate on a daily basis. If my thinking is correct, there should be ammonia appearing in a couple of days. I,ll let you know how it goes.

 

[Alien Anna]

I,m going to do an experiment when I get home tonight. I,m going to put some nitrogen rich fertilizer in a 10lt container with a plant. I,ll measure the ammonia, nitrite and nitrate on a daily basis. If my thinking is correct, there should be ammonia appearing in a couple of days. I,ll let you know how it goes.

I couldn't quite follow you the first time. You're talking about denitrifying bacteria? The sort found in compost heaps?

Tell me how your experiment goes. I'm not too convinced but then I am a sceptic about everything, as you know.

 

[aquamanis]

Hi, well this isn,t the experiment I was going to do but it occurred to me I dont need to. See I,ve got a hydroponic setup going, has been for about 3 months (this crop). The only thing that I put into the water is the nitrogen rich fertilizer I was talking about. The system works pretty much the same way a planted aquarium does. Water is pumped from a sump to flow down and through the roots which are covered by volcanic clay (simular to aquarium gravel) and then back into the sump or resovoir. There is a heater which keeps the water at 24c and an airpump and airstone under the roots. (you can see how simular the hydropnoic setup and an aquarium are). So this morning I took a reading on ammonia, nitrite and nitrate. Well despite having an EC of 2.4 which is 2400 ppm of salts(nutrients), there was no ammonia and no nitrite. What supprised me the most is there was a nitrate reading of 15-20ppm of Nitrates. What does this mean? Basically it means the nitrogen has been converted into ammonia then nitrites and then into nitrates. The same as an aquarium cycle. So if this is true, one should be able to cycle a planted tank with normal nitrogen fertilizer. This is what Chuck Gadd was suggesting in one of his articles, that plants can convert nitrogen into ammonia, then of course the bacteria converts it to nitrites, and so on. This has me all excited now, I will do the experiment properly as soon as I get the appropiate items. I,ll let you know what happens.