Backyard Aquaponics
A place to discuss aquaponics

Originating in the "Worm Farm Tea" thread, I am further toying with the concept of utilizing a worm bed to consume solids and help filter suspended matter. On a simple home scale, having the worms in the grow beds may be sufficient, so my focus here is scaling up where higher amounts of solids will occur. These solids and other wastes can contribute to a food source for pythium, potentially causing root rot and other disease symptoms.
A separate bed will allow for greater surface area for worm cultivation and filter channels to keep up flow rate of water, while providing a separate waste control system from the growbeds.

In this design water fills in through larger, free flowing media to facilitate even distribution of detritus and matter. On top of this redworms would be cultivated in bedding, which stays relatively dry compared to saturation within the media, allowing for separation of supplemental feed scraps to the worms.
I feel this may be necessary to keep a larger population of worms ready.
(It may indeed be the case that having the bedding on top of the gravel is not required and one could simply supplement feed via a ground meal, say corn flour/meal, right onto the dry surface of the gravel where the worms may access it.)

Water then filters through fine media to help clear smaller particles, then flows through a mesh wall into a small reservoir to allow for consistent drainage control. Perhaps coconut coir may be appropriate for the fine filter, otherwise coarse sand may work.
The two layers might be separated by a stainless steel cage, or shaped plastic mesh box for the gravel.
It appears it may be beneficial to keep high oxygen levels in a sand based worm filter, therefore an ebb and flow flood cycle is sought.....see magically relevant research abstract here(unfortunately restricted access to data): http://scholar.lib.vt.edu/theses/availa ... 03-205902/

Hopefully a device such as this will reduce the amount of waste build up in growbeds of solid media like gravel.

Edit: Perhaps an airline and distribution hose in the sand or gravel to help oxygenate the filter may be of benefit

Hayden

I'm also keen to integrate worms into my system.

My idea is to stuff one of my existing biofilters full of shade cloth (or similar) and, once it's had a chance to get some fish wastes in it, put a handful of worms into it.

Warren, remember that, although their bedding passes through them, composting worms actually eat bacteria (rather than food) .....so anywhere the same bacteria will thrive, so should the worms.

Anyway, we'll know the outcome soon enough......I'm going to put the new biofilter arrangement together next weekend.

Gary

U sure about all that gary?

I was under the impression that bedding was also consumed, hence the importance of the correct C to N ratio, and they certainly eat food scaps....

But i may have mis understood

Sorry Gary, I keep forgetting to post my actual name, it's Hayden.
The bacteria is a predigestion for the food scraps. I believe they definitely do consume foodscraps, along with the bacteria. I have heard this arguement disputed several times before. It appears that while normally the worms need carbon and nitrogen sources as food and bedding, that in a sand filter as per the abstract I linked to, they will build up a mass without bedding.
I would love to get a hold of the actual research data, but it really is not needed as we at least know it works.

The reason why I am concidering media other than shade cloth is to help pull suspended fine particles from the water. From looking at other intensive systems, even when a shadecloth or similar media filter is used, there are still large amounts of suspended matter in the water, coating all surfaces in the system. A finer filter of sand that self cleans itself with worms may be very effective at digesting these particles.
If bedding is not needed, much more depth of the bed I posted could be filled with fine media to allow for higher flow rate. Perhaps vertical with a different timing mechanism may be successful here...say a barrel.


Hayden

Hi Hayden,

I apologise for calling you Warren....I don't know where that came from.

Guys......I got my understanding that worms eat bacteria through multiple readings of David Murphy's book "Organic Growing with Worms." Murphy is one of Australia's leading authorities on worms

Some quotes from his book.....



Upon closer reading, it seems that they eat "micro-organisms - algae, bacteria, fungi, microarthropods and protozoa" so I gues that we're all still in the race.

In any case, I think your investigations of the impact of worms on an aquaponics system are worthwhile.

Gary

Did I do a write up about the bio-film (bacteria, algae etc) being the main food source for streams here in NZ yet?

Bunch of educated types removed leaf litter from a stream by placing netting over it and watched the results.

The insect population changed, but did not subside. More fine particle matter invertebrates arrived and grinders dwindled, BUT, the fish population and growth rates remained constant.

End results were -

The dietary energy and nutrient content was coming from the bio-film, not the leaf matter.

That's why I let veg rot in system instead of blanche them. Let the bio-film do the softening (enzymes attack cellulose walls etc) and the nutritional content is higher.

I think this would apply to worms, and the bacteria they consume need to be fed, hence the scraps/solids.

Excellent points Aquaaddict, looking at the anatomy of the worm though shows a gizzard where muscular contractions break down organic matter with the aid of rock grit.
Side note: amazing what random searches will bring up:
http://www.ncbi.nlm.nih.gov/entrez/quer ... t=Abstract

Ahh here we go: (Eisenia fetida are very similar in anatomy to earthworms and this is pointed out in the article)

"The earthworm's digestive tract is highly adapted to its burrowing and feeding activities. The worm swallows soil (including decomposing organic residues in the soil) or residues and plant litter on the soil surface. Strong muscles mix the swallowed material and pass it through the digestive tract as digestive fluids containing enzymes are secreted and mixed with the materials. The digestive fluids release amino acids, sugars, and other smaller organic molecules from the organic residues (which include living protozoa, nematodes, bacteria, fungi, and other microorganiams as well as partially decomposed plant and animal materials). The simpler molecules are absorbed through intestinal membranes and are utilized for energy and cell synthesis."
from here: http://edis.ifas.ufl.edu/in047

Another relevant article:
http://www.wormman.com/ph_of_your_soil_and_worm_bed.cfm

Any ideas on design for increasing water flow while maintaining the fine filter media, or on building an ebb and flow into this, while reducing used ground area?
My challenge is that I like the flood reservoir concept for flood timing and want to keep its adaptability, along with the continuous flow pump and biofilter abilities. Since the vermi-filter does not need sun, it would be great to locate it under the flood reservoir.
The question is, is how to incorporate a fluidized worm bed as a constant from the fish tank, and not just the intermittent flood from the reservoir? I do not want to allow unfiltered water to go to grow beds.

Yes, I am guilty of trying to make people think and theorize...including the majority of you from Australia and New Zealand. . I have an Australian friend here.
He is my local idea wall to bounce off of. Smart guy.

Hayden

A few factors I am trying to work into this are:
1. Not having impeller pump previous to the filter. The less the solids casings are traumatized the better in regards to suspended particles levels.

2. Continuous flow on the pump. Pump life is greatly increased by not having to switch on and off.

3. Keeping the numbers of impeller pumps (higher energy use) down. Airlift is something I am trying to incorporate. The geyser pump may be a good candidate here due to higher lift capabilities, for lifting water to the flood reservoir.

4. Allowing a wider pore area for letting solids separate better in the vermi-filter (the larger gravel) preferably at the top and accessable. It's easier to hold larger gravel in mesh than sand, plus using gravity to move water through the sand is positive.

Yes I realize I am making this difficult.

My first thought is a low lift airlift from the fish tank to the similar height of the vermi-filter. But then how to continuously run the pump without it possibly running dry.
Having the vermi-filter higher than the flood reservoir and/or growbeds seems beneficial in this case, but then it is a potential obstruction in tighter space.

I wonder if having a perforated airline in the bottom of the sand and having the vermi-filter continuously flowing would agitate the sand too much, with all that weight on it from gravel? This would solve the continuous flow pump issue along with providing high oxygen levels.

Hmmph.
I think I should do something mindless for a while.....maybe not

Hayden

Well, you lost me ages ago. You want to keep it simple, but it doesn't sound simple. Maybe I am simple, I can live with that.

I presume the point of the exercise is to utilise worm rum and castings as nutritional input for your plants. This means you want - Tank to worms to plants and back. The pump should never run dry in this instance, it is a closed loop.

A fluidised sand filter with worms added, in the loop. Done.

I could be off track.

I envisage an easier way. A worm farm sits in part of your growbed. The bottom of it is mesh containing fine gravel ie 5 mm pea gravel or similar. This is the part that gets ebb and flowed as your bed gets ebb and flowed, it is under the 'high tide' mark. Above the water line is a typical worm farm, which you dampen with AP water regularly, and add food scraps, when you feed the fish.

The nutrients will be dispersed from throughout the bed with the worm farm and into the tank/pond and out to other beds that don't have a worm farm.

Solids are not a problem in ebb and flow gravel beds, they are a valuable source of additional nutrients hence the awesome tomato results we all get. Pulverising them just helps the bacteria's job.

A worm farms additional benefits will only be fully realised by additional inputs into the worm farm. Otherwise you are only recycling what is already there. Adding food scraps to a 'dry' worm farm will provide the nutrients required to farm large amounts of bacteria for worms consumption. Moistening it regularly will create a trickle down effect, your AP will love you for it.

Ah, reading back - short term memories not what it was - you want to stop pythium, and solids build up. Well, growbeds will do that, and a pump that smashes the solids.

Being in Canada you should have lower temps than these Aussies too, pythium likes it warm. It is more a hydro problem than an AP problem, unless you are going into nft, which requires a bit more planning.

I battled with pythium, then I stopped messing round and added a solids filter, good aeration, reasonable temps - no discernable pythium. It's always there, the spores are everywhere, just keep good conditions.

And..... Keep it simple, the more stuff you add, the more things that can go wrong.

Ok to clarify:
In small scale system, gravel beds can handle the waste. Ramp up the feeding and stocking density to commercial production levels and the labour needed to clean the gravel...an absolutely mandatory process, becomes great and time consuming. This has been demonstrated before.

Simplicity is an element here. Continuous flow pumps and flood reservoir system is the epidemy of that. However to further the technology of AP we need to apply control mechanisms. Even with a dedicated solids settler and clarification tank, there is still suspended particles in the water from one degree to another. I am aiming to solve this.

Being in Canada is irrelevant. The aim is warmer water fish such as tilapia. Other fish may be feasible and new legislation will be applied soon to allow commercial production of other species. At this point, Tilapia is the most attractive. Dr. Nick Savidov at the CDC in Brooks, Alberta, has demonstrated very clearly the essential requirment for solid management and regular cleaning. It is basically a matter of labour reduction.

Thanks for your input. I look forward to more.

This CAN be done, and with simplicity and complexity working together
Have faith, the bacteria gods shine upon us APer's

Check out osmoregulation before you try removing all particulate matter.

Going commercial is another ballpark, yes. Commercial operations don't clean gravel though, if they do it's a poor design, they clean filters.

Worms in your filter will regurgitate the contents, not remove them. However, it will be more bio-available to plants after worm processing, which I'm guessing is the aim.

The real trick, imo, is gravel beds with plant filters followed by water culture with further plant filtration. There is a point where the nutrients will be used up.

Some plants may need to be specialist filtering plants, that take up heavy metals etc, as opposed to food crops.

Good luck, I look forward to seeing what you try.

whats pythium is it good or bad

pythium = root rot. High temperatures and anaerobic conditions will cause it to flare. It's a fungi.

Wow, so much to read! I have skimmed over the latest posts, keep the brains going guys, great stuff!

One question (although i may ahve missed something crucial) A true fluidised bed sand filter would make shot work of the worms wuldn't it? One of the benefits of a fluidised bed filter is that it grinds solids into fine particles due to the abrasive sand........i can picture a worms soft skin