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About Shadders

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    Brisbane, Queensland

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    Vermiponics, iAVs, Sustainable agriculture
  1. I put these quotes together to demonstrate that their will in fact be food available for the worms. Worms have a marvelous behavioral property in that they will self regulate their biomass to match the food supply. If there's not enough food worms will actually shrink (and some may die providing food for the other worms). If there's more than they need they grow larger and make more baby worms. So yes they'll probably still flourish, but if there's less food not in as high a numbers. One thing to remember is solids filters are not 100% efficient. I think swirl filters and settling tanks acheive about 60-70% efficiency (if memory serves me correctly). Finer sponge filters after this stage can increase it higher. I can't argue with the benefits of worms (that's why I'm planning to build a fishless system powered by worms) but they are primarily benefits to plants. Although I might argue with point 4. Worms are actually extremely valuable, they retail for about $100/kg in Queensland. Fish feed is a lot cheaper. But since we are now talking about primary benefits to the plants that changes things somewhat. You've stumbled , quite quickly, upon the inevitable truth of AP which is that it is a compromise. What's ideal for plants is not always ideal for fish and vice versa. There is some symbioses (the nitrification cycle and the fact that both like well oxygenated water) which arguably is what makes it worthwhile. But in many other cases there is a conflict of interest that must settled by compromise. e.g. Plants typically prefer a lower pH than fish. Plants would prefer as much fish poop swimming around the system as possible, fish would prefer none. I can't recall the exact numbers but solid fish waste still contains something in the region of 70-80% of the fish feed nutrients in a non-bioavailable form. What do with those wastes is one of those compromise decisions. If you want ideal conditions for fish, take the wastes out of the system (They can still be used usefully outside the system). If you want ideal conditions for plants, keep them). If you want the best of both worlds get as much nutrient out of them as possible and keep them away from the fish as much as possible. This is where mineralization comes in. And quite rightly you point out that worms are one way to achieve this (and provide a number of other benefits in the process). There are also other methods of unlocking those nutrients (google offline mineralization). Bluesmart Farms send their solid wastes (along with some water) on a separate circuit to a dedicated worm bed then return the water after the worms have done their work and made most of the solid waste nutrient into a bioavailable/soluble form. This adds complexity to the system but appears to be an effective mechanism. The system is described in fair detail in their patent here: . Don't get me started on the patent though. Basically they've added worms in a separate bed and tried to patent aquaponics In order to work out the best way for you go it would probably be useful to clarify some points. 1/ Are you prepared to remove up to 80% of fish feed nutrients and accept the consequent loss of plant growth? If yes, then a solids filter between fish tank and growbed, dump the waste on the garden. You can still have worms but their population will be smaller. This is the option that provide for best water quality for fish with the simplest build. 2/ If not, are you prepared to add complexity to the system? If yes then as above but put the solids from the filter into a dedicated flood and drain worm bed and return the water to the system periodically. You can also recycle plant wastes in the worm bed. Instead of a worm bed you could use offline mineralization (which is simpler) but you want the benefits of the worms so this is an option. Alternately consider a dual loop system. 3/ Are you prepared to compromise on water quality for a simpler build and better plant growth? If so then a simple system with worms, no solids filter, but a ratio of fish to plants biased in favour of the fish (less fish more plants/growbed). 4/ Are you you married to the idea of a gravel/clay ball grow bed? If not look at iAVs sand beds. Very simple build, maximises nutrient extraction, plant yield, solids filtration and biofiltration. The only downside I've seen so far is that sand beds are about double the weight of an equivalent sized clay ball bed. To my knowledge no one has experimented with worms in an iAVs system though. I might be the first, unless you beat me to it. One last thing. Be careful using a UV sterilizer. I'm not sure what you want to sterilize but AP relies on bacterial populations. It will sterilize the beneficial bacteria as well.
  2. Worms do produce ammonia but it is negligible compared to fish and their effect on microbe ecology will more than compensate from any additional ammonia they produce. In terms of sizing a media bed take a look at the fact sheet by Dr Wilson Lennard here: sheets.htm As to whether you should have biofilter or mechanical filter that depends on a lot of things. Since your primary interest is the fish I would say if you're media bed is large enough to provide biofiltration you'd still be advised to have a mechanical filter to remove solids. It's import to understand the different processes that happen in an AP system and which components function to facilitate those processes: Ammonia production (and introduction of other elements): usually this is done by feeding fish and waiting for them to poop. Biofiltration (conversion of ammonia to nitrite then nitrite to nitrate): This can by done by a media bed (though it's not as good at doing that as many other methods so it's efficacy depends on size). Removal of excess nitrates: In aquariums it's usually done by partial water changes and dumping the removed water. In AP this is normally done with plants although it can also be done with denitrifying bacteria. The UVI system made use of nets suspended in a tank to host said bacteria and they controlled nitrate levels by controlling the population of these bacteria (hosing off the nets to remove them if they wanted nitrate levels to rise or allowing the bacteria colony to grow if they wanted nitrates to drop). Mechanical filtration (capture of the solid waste): Again this can be done by media beds but quite badly. The disavantages are that the capture is incomplete due to large pore spaces in the media and that with the sludge trapped in the media beds you can't really do much with it, removal is hard without pulling out all plants, and the only mineralization option is worms and a lot of time. Worms help a lot but do not solve the problem completely. They still produce waste even if they reduce the volume of it. Other methods of mechanical filtration are swirl filters, sponge filters, sand beds etc. Mineralization (extracting further nutrients from captured solids wastes): Worms do assist in this process. However if you aren't focused on the plants you might not want to do this at all. You could simply capture the solid wastes in a mechanical filter and use them to fertilize the garden, compost them or even just discard. Of course there's always the option of an iAVs sand based growbed which does all of the above very well apart from the Ammonia production. With a bed the size you're proposing you might be suprised at how much produce you can grow. But if you're set on a gravel or hydroton growbed I'd at the least have a solids filter in place assuming the gravel surface area is adequate to convert your expected ammonia output. The system may work without one, that depends on a lot of things. But there's no question that with one your fish will be happier, healthier and grow faster.