If you can run your tank on a natural cycle, you could theoretically have organic material with anaerobic/aerobic bacteria, nitrates, phosphates, ammonia, and other trace minerals, but keep in mind the filtration, if using activated carbon, is absorbing any nutes suspended in the water. There is only so much in the layer of substrate you are using. Once disturbed, you will see the dark layers in sand or between rocks, and perhaps bubbles of gas. If your tank is planted and you use miracle mud/peat etc with fresh/marine algae refugium, you can produce a nearly controlled environment of kelp, chaetomorpha, and various living organisms in a seperate unit which acts as a living filter. This explanation is probably fragmented but im high.
I believe under normal circumstances, wastewater from a goldfish bowl would not really be all that beneficial, but better than nothing. However, if you were a serious aquatic grower and understood how the entire ecological cycle worked, you could create yet another use for your refugium. Or perhaps if you grew shrimp as a farm job... the sludge would be great for outdoor plants.
I also would not use water from any tank that has any chemicals such as Start-Right, any type of Chelated Copper medication, algicide, or ick-rid. I wouldnt want to put it in my body so I wouldnt want to put it in my plants either, especially since it is still going into my lungs.
add: I have taken care of a lot of marine and freshwater aquariums, including breeding discus, a tidal marine aquarium and a shelf reef that were completely self-sustaining, including feeding, pH balancing, nutrient regulation, foodstock production, and waste management (though I dont think I needed to, I still changed 1/3 water every 2 weeks. Its always good to get fresh air.)
The benefits of recreating the ecological cycle is that once to connect the ends, its amazing to see what goes on at every level. I like the idea of the use of tarantula, pirhanna, etc in hydro solutions because beneficial as well as detrimental bacterias are necessary in proper growth, be it plant, animal, or human. If we took care of ourselves and each other as well as we take care of the plants, we would be as healthy as some of our plants.
. But I will remain optimistic because of the knowledge that you all have shared with me. The plants are in a flowering stage and nearing the middle to end. I know that some defic is natural but they are and have been defic for a minute before this time. I have no filter in the bowl (just a glass bowl with water and rocks/pebbles and a plastic plant) and I cut it with a half gallon of water from the tap, 7.0. The one that I had used it on was one that was still mostly green and not really yellowing as of yet. It eventually started to show earlier today a bit of yellowing, but I only gave them the nutes ( organic mix of grow and bloom nutes on one and the other I put only the bloom nutes and fish water) yesterday and I believe organic nutes to take a minute before they take hold.
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Good luck!
