I have looked at the worm debate a few times, but have not added any in my systems yet. First, I will have to try and find the correct species down here. Second, due to the lack of volcanic rock and the robbery price of hydroton, my systems are entirely gravel. Can worms really navigate the heavier media?
Thanks a stack Sahib. Now, next question - does anyone (I do not have Murray's DVD, in case it was in there) have the species or at least genus name of the correct worms for the job?
Sahib Punjabi said:Video from Murray Hallam - AQ Secret Weapon...Worms...in gravel :-)
Kobus Jooste said:I have looked at the worm debate a few times, but have not added any in my systems yet. First, I will have to try and find the correct species down here. Second, due to the lack of volcanic rock and the robbery price of hydroton, my systems are entirely gravel. Can worms really navigate the heavier media?
Being new around here, I keep on stumbling on topic's older entries that I feel I can add to. I have read through most of the buzz around "nutrients", but as ecosystem energetics is a focus area of mine, felt compelled to want to add something about this.
Whether you add or do not add anything other than fish food is your choice, but note that animals do not need all the elements required by plants, and thus the most expensive fish foods may still not do the job. That said, when I see an aquaponic set-up, I see an ecosystem. In energetics, we normally describe the passage of either carbon or nitrogen as it passes through an ecosystem. You have your introductions, or sources, you have your various trophic levels of users, and ultimately you have your exports and recycling pathways. It is in those pathways that aquaponics finds its strength. You do not want to export like the dudes at UVI. It is done in gravel, in net tanks, in biological filters and even on a dense mat of roots. The processes that we want to see happen in aquaponics all consume oxygen, but give us the nutrients in its most basic form, which can then be absorbed by plants.
As those with gravel beds may know, you can run an AP system without fish for a long time, and the plants may still grow. That is because of the slow process through which solids continue to be broken down (mineralized) by microbes. At a far greater pace, bacteria can deal with dissolved nitrogen and give us nitrates in return. If you wanted to, you could take it a step further and denitrify, but then what would that help. So you have "fast" nutrients coming from bacterial actions, and "slow" nutrients coming from all the microbes dealing with the solids. The fast stuff is normally macro-nutrients, while the "slow" stuff is often a lot of the trace elements and micro-nutrients we all feel compelled to add. What the worms do, is speed up the mineralization of the solids - putting it through its gut and releasing a form of nutrients that is available to plant. Without the worms, the process will take place, but slowly - you also have the chance of "loading" faster than what you can break down, leading to clogged beds.
Worms therefore mobilize nutrients from a "sink" situation, where it is gunk in your gravel bed, through a fast nutrient recycling pathway back to a soluble state available to plants. Great stuff for AP. As a side, they do consume oxygen and part of the solids they chow becomes biomass, thus it is not all free for you, but it still helps a great deal.
I'm not sure if anyone else have replied on this. Duckweed (which species though?) and some source of insect protein such as worms or black soldier fly larvae has been proposed as a sufficient nutrient base for tilapia, but I have not tried it. I am working towrds creating a duckweed (Lemna gibba) aquaponic system for research purposes. The basis for my research is that Lemna, and most other duckweeds, can concentrate nutrients in their cells as far greater concentrations than in the water. Manipulate their water, and you may be able to grow a complete diet for tilapia. Mine (Mozambique tilapia) absolutely love the stuff. I supplement with it at the moment, but as the research matures, I'll do more detailed trials. Just for interest - most tilapia foods contain mid 30% protein of fish meal source. Lemna can be grown to have a more digestible (but very close to animal) plant protein concentration of over 40%, lipids up to about 9% and carbs of up to 43%. It can also absorb every trace element, metal and nutrient needed in aquaponics. Thus, grow it correctly, and my hypothesis is that it can become a single, or one of two dietary items needed in an AP system.
Joseph Orlando said:
The composting worms I got were a combination of eisenia foetida and lumbricus rubellus. We have occasionally fed worms to the fish and I've never noticed any of them being rejected. However, it can be a challenge to grow enough worms to really make a big dent in the feed requirements. Same as the situation with growing duckweed, I've never quite developed a method to grow enough easily.
Worms are generally quite easy when you are just running a small worm bin or worm farm you get to harvest castings and feed them your kitchen scraps and perhaps pull out a few worms to feed to the chickens or fish. But, when you are talking about wanting to harvest pounds of worms per day or week, you suddenly need a far larger feed stock for the worms than just some kitchen scraps or fish poo. Feeding enough to have a large volume of worms ready to harvest regularly requires a waste stream enough to feed them up as well as a ready supply of bedding material to keep things from getting nasty.
So we have established that worms can be fed to fish and worms can be put IN the plant beds to break down solids. I have also heard of having a seperate compost bin and then adding the worm castings to the plant bed. Does anybody know more about this? Any thoughts on amounts? Doesn't it make the water dirty? Just like adding dirt to the water?