Why I wont get fish for now and compost tea experiment

The farm from above

Its been over a month and half now that I have set up the tower farm. In the process of cycling, I have discovered that eggshell can release ammonia (I should have guessed right ?), that pH drops quickly once the beneficial bacteria are established, and that the pH climbs back up in absence of new ammonia. I have also lost my green onion and basil.

The farm from bellow

pH has decreased then increased since no new ammonia was added

Since the system has "cycled", I have hesitated in what fish to get. I will not get fish for now. Why that ? After all the point aquaponics it to get fish to right ?
The reason is that I decided to have an apprenticeship about aquaponics with  Citizen Schools and while discussing with the Citizen Schools people, the fish seemed to be a down side for my plan, so I ruthlessly removed the fish from the picture.

Citizen schools is an association that brings professionals to teach after hours classes (apprenticeships and other programs) to selected middle schools in NYC. Only schools that have 85% of student who are eligible for free or reduced lunch due to their parents low income. Since the fall semester I have been volunteering there for an apprenticeship where we teach our students about heart health. Anyway, A few weeks back I proposed to have an apprenticeship where we would build an aquaponic system with the students and learn about the basic science behind it. So after discussion with the school staff I settled for an "other"ponic system, instead.


Since my all point about starting the system was not only to grow some food at home, but also on a sustainable manner, hydroponic seems like a bad alternative to aquaponics. From the sustainability point of view, hydroponic seems a bit difficult given the need to do full water change, and the need for concentrated fertilizers. An Internet search for compost tea tends to make one inclined to believe that compost tea is the panacea for organic gardening, because of beneficial microbes and a balanced NPK. This is why I have been experimenting with compost tea.

The farm has cycled, and nitrate dropped to 0

I have been making compost tea in the last 3 week ends, increasing the amount of worm compost each week. After "brewing" the tea, I measure the amounts of nitrate and ammonia. So far, I was not able to have a nitrate (or ammonia) level above the detection limit. last week end, I have "brewed" a compost tea using 1/4 of a cup of worm compost, 1 table spoon of molasseses (unsulfured) and shredded seaweeds in 2 cups of water, brewed it for a day and half. After a days and half, it still smelled like molasseses (I like that smell).  I also added some of this greengrow plant food, very diluted. Because I have just seen the nitrates dropping, I decided to add some ammonia source, I though about eggshells, but the pH has increased to 7.4; so given the pka of 9 for calcium carbonate (witch is what eggshells are made of)  I am not sure it is a good idea. Instead I bough a 1/2 gallon bottle of ammonia at the dollars store and added one mL (a bit less than 1/4 of a teaspoon) of it on Monday and Tuesday ( gave ~ 1 ppm reading) nothing yesterday, and now ammonia is back to 0. I will keep adding 1ml everyday for now, until I figure out how to make a strong enough compost tea (if that is possible).
I am keeping track of my experiment hoping that I could make a sustainable "tea"ponic system for the school.

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