Backyard Aquaponics
A place to discuss aquaponics

The main reasons some are running seperate biodfilters are:

1. Not enough suitable media for hosting the nitrosomonos and nitrobacter to convert ammonia to nitrite and nitrite to nitrate.

2. Ability to potentially seperate plant side of system from fish side of system should either of them need to be treated or fertilised.

A biofilter could potentially remove some of the solids for you - but could also potentially block up because of this - resulting in need to clean regularly. I believe Gary is considering putting worms in his next biofilter and this could work in breaking down solids.

If I were you I would put a/some gravel bed/s before the NFT. Put some worms in these beds and use them to grow stuff also. They don't have to be huge.

Stu - I tend to agree - but only time will tell. I never did take that picture for youGary of how dirty the water is int he bed if you dig a hole. I will do so soon. When I did the removal of my outer standpipe on the weekend to drill more holes in it, I dug a bottomless bucket in around the standpipe, removed all the gravel and then took the pipe out. There was a few mm of silt-like gunk that has settled on the bottom of the grow-bed. The drain wasn't sitting flush with the bottom - so this probably helped in stopping this crap from flowing into the fish tank.

Take a look at this pic

VB, here are the "dutch pots" Im thinking of using to trap/filter some of the solids before distributing the water to the nft channels which will be along the walls...

Measure 300x250x200, have inbuilt siphon... probably plant with strawberries...

Do you think they would be big enough to do what I'm proposing?

and would they be big enough to be self sustaining without cleaning/clogging??

Or would I be better off in your opinion using full growbeds and the trying to incorporate these "pots" and the nft channels after the growbeds???

What would the medium be int he dutch pots if using as the biofilter (gravel??). The existing syphon is not going to work for you unless you can cover it to stop medium from getting in there. Not having the drain through the bottom means you can't use the standpipe cover type system we use - which will make it difficult for you to clear roots.

Clay balls... gravel would probably be too heavy/problematical to attach to wall ... rented house...

Existing siphon has three small crenelations around lowest point of siphon..

they're not that large and I thought clay balls would be OK...

these are kind of like the auto pot idea in as much as there always remains a small amount of water below the "step"

Hi All,

On the issue of removing solids from the system......

In my system, some solids (in solution) will be removed whenever I water the non-recirculating growing systems. That's fine, because the only benefit in having the solids remain in any system is to provide a wider range of nutrients....particularly for fruiting plants......and the solids that are removed in my system are going to those plants anyway.

My bio-filters have a reservoir below the outlet pipe in which sediment settles. I remove this periodically by tilting the bio-filter and draining the sediment into a bucket. This 'sludge' is applied directly to the coco peat for my fruiting plants.

On removing nitrates from the system.....

Trickling bio-filters like mine are designed to facilitate the colonisation of the bacteria that create nitrate. The action of trickling down through the oyster shell media, however, does cause some gaseous exchange which, I believe, has the effect of flashing off some of the nitrates as nitrogen in a gaseous state.

The action of removing water from the system.......to water my non-recirculating growing systems.....also has the effect of removing nitrates from the system. Currently, I lose about 80 litres of water every two to three days.......an average of about 40 litres per day......through evaporation and through feeding my non-recirculating growing systems.

This is amounts to an average daily water replacement of 7% of my total water volume. I'm given to understand that commercial aquaculture systems change 10% of their water daily. The difference between their systems and mine is that they dump the water where I use mine to feed my coco-peat systems. In either case, the impact on nitrates is the same.....they are removed from the fish tank......to the ultimate benefit of the fish and the plants.

My small gravel growbed is also responsible for some of the nitrate removal. I have silver beet growing in this unit and it's a nitrogen-hungry plant.

Rupert.....I'd find a way to remove the bulk of the solids before the water makes its way into the NFT system.....to avoid the clogging that may otherwise occur. It could be as simple as running your water through a tub full of coarse coco peat before it goes to your NFT systems. This will have the effect of preventing too many solids from going into the NFT troughs while still keeping all of the nutrients in your system. You could replace the coco-peat in the tub at periodic intervals with fresh material. The 'spent' coco-peat will grow just about any hungry plant by the time it gets loaded up with fish poop solids......or your worms will enjoy working their way through it.

Gary

Hi njh,



Sorry 'bout failing to respond earlier but I only discovered your question when re-reading previous posts.

A good quality Coco peat :

- offers excellent aeration and structure around the root zone of plants

- is free of the plant pathogens that frequentl soil.

- holds up to 10 times its weight in water.

- drains well - is virtually impossible to over water.

- will not compact over time as does soil.

- lightweight (when dry)

- may be used in re-circulating applications. In re-circulating drip systems it is recommended that the fiber be mixed 50/50 with either coarse perlite, pumice or grow rocks for faster drainage.

- suitable for flood and drain applications.

- near neutral pH value.

Gary

I haven't watered my coco-peat trays, tubs and pots for 5 days now. We've been getting the occasional shower and that has kept things nice and moist.......and the plants seem to really love rainwater.

I've cut back feeding in anticipation of rising ammonia levels. I'll test tomorrow morning to determine what's happening......and I'll feed the plants, too.

Every day for the past week, I've been feeding the fish 2 parts of fish pellets, one part of duckweed and one part of soldier fly larvae......today it was just a small handful of frozen larvae.

While I'm keen to trial a different bio-filter setup, and I'd like to experiment with a fluidised bed filter, this system is now basically in fish growth mode. I'll probably have to add some more tubs and trays as the nitrate levels increase (due the increased nutrient levels as the fish grow).

Rupert, the dutch pot has plumbing at the bottom, but I can not see in the photo whether it comes thru the bottom and terminates on the step or thru the side and terminates on the bottom. Crenelations is too big a word for me, does that mean it is slotted, or notched, or what? I am planning a 100 gallon sump with the drain entering the side. I was going to do a 90 and have a pipe up to the water level I wanted to maintain ~15"(38cm)with notches around the top in case I float a raft on it. What does anyone think of that? This may be a fingerling tank or seedling tank, or both, or none of the above (just sump).

Doug-
Check out MF's drain. He uses something like that, but uses a pipe that goes to the bottom of the tank to get detrietus up. Think of a Bell Autosiphon without the top. That way, when the water gets above the specified level, water runs out, but the water that runs out is pulled from the bottom center of the tank where the fish poo collects. He also used his input pump to push the sediment toward the drain.

Sometime back, when the discussions about using homemade fish food was happening, I proposed the idea of feeding duckweed (plant protein), larve or worms (animal protein) and some grain product.

You may recall that I spoke about feeding the animal protein first (because it's usually the most expensive) followed by the grain (because it's also purchased) and following those up with free choice duckweed (because it's free, it floats and doesn't contribute to foulling of the tank.

I've tested duckweed and it works and my recent experiments with Soldier Fly larvae have certainly exceeded my expectations.

In fact, I've been feeding a mix of fish pellets (2 parts), frozen BSF larvae (1 part) and duckweed (1 part) for the past week or so.

Today, I bought some brown rice to determine whether the fish would eat cooked grain. I boiled up the brown rice and allowed it to cool before giving it to the fish.

They definitely eat brown rice!

The only issue that I have is that the rice sinks quickly so the fish need to be hungry (and on the ball).

I'm changing my feeding regime so that the brown rice will get fed first (because it has to be purchased and because of its ability to pollute the tank water if not eaten) followed by the BSF larvae......with duckweed for dessert.

This regime avoids all of the smelly, time-consuming concoctions that are involved in mixing and cooking ingredients......and (hopefully) will not impact water quality.

The basic ingredient mix is also likely to be useful for formulating rations for other small livestock like quail and chickens. I just have to fiddle with the proportions for each species.

My next task is to locate a wholesale source of brown rice.....to get the price down to a sensible level. At the moment, the fish pellets cost me just over AUD$2.00 per kg.

Even if I have to pay that amount for brown rice (for the relatively small quantities that we are likely to use), I'll have total control over what my fish eat......without the chemicals or questionable ingredients.....for much less than what the commercial rations will cost me.

I've frozen the cooked brown rice so that it is easier to handle, so that it retains its vitamin and mineral content, and to prevent it from going mouldy.

It still sinks like a stone.....but the fish are quicker.

Meanwhile, my latest bunch of soldier fly larvae continue their onward, upward march along the ramp.......dear little things.

You might want to try sprouting the rice instead of cooking it GD.. I was supplimenting my feed with sprouted brown rice and sprouted lupins for a while. They aren't super keen on it, but they'll generally eat some.

Hi EB,

I'll have to try sprouting some. Either way, I'm happy with my progress toward a balanced (more or less) homemade ration.