Making bio filters

[CQ AQUA]

Hi, is there any sort of guide on what size filter for what size tank and fish loading.

I'm making my system myself as much as poissible. Through my work i've got access to plastic 205 ltr, 20 ltr drums. I think they'll be handy but am unsure how to make them and how many of what size.

The system will have a 4500 ltr tank and i want to run as many growbeds as i can fit ( how many could i do ??? ). And how many fish could i stock?

I'll look forward to your replies.

Regards, Jim

[fishfood]

Hi welcome to ap madness for a rough figure 2 to 1 is a rough figure most of us work on [4500 fish tank 9000 litre beds] it depends on fish load plant load etc[ the more fish the more plants you can have also size fo fish] just a tip look at established and new systems thread and read them all
sit down and look twice defore doing things [its a lot easier to do it once]
i am running 3, 1000litre tanks all using the same water [ 2 different tanks of fish and 1 tank smaller ones] gives a constant fish load otherwise when you harvest all your fish [you have nothing to carry the plant load]
ask a lot of questians some won will be to happy to answer
enjoy the trip
currently i have 30 silver perch 12 in long 70 silver perch2 to 4 in long 50 trout 6 in long trout will be ready before xmas
[to hot in qld for trout]

[CQ AQUA]

Maybe i've asked the question too ambiguously.

I'll be using 8 2mtr x 1mtr x 400 mm grow beds but i'm concerned they won't be enough. Thought's please.

So what i've considered is having a bio filter after the grow beds and before the sump or on a seperate line. Any thoughts on which will be preferable to achieve a good result?

I'll rapidly be aiming to have the system running near full capacity so don't want to overload things.

Thanks, Jim

[fishfood]

If useing a seperate biofilter it should before the beds

[Hamish]

Yes - before the grow beds. Or you could do what I do and have the biofilter (in my case a canister filter) running off the fish tank seperate to the water pumpin through the grow beds. This way you have backup if your main pump dies - and you can also seperate the tank from the grow beds if necessary and still have biofiltration for the fish.

[nick]

you will be fine with the growbeds to fish tank size. by my calculations you have 4000litres of growbeds to 4500 litres of fish tank. As a biological filter that volume of growbeds will be fine. I think traditionally 3kg of fish per 100l of growbeds is the figure used so on that you would be looking at 120kg of fish in the bed.

You do not need additional filtration if you are running about this number of fish. Also to help you thinking, this could mean you could get 300 fingerlings and grow them to 400-500grams and then harvest half of them out at this time and let the rest grow on to 1kg anf have fish to share.

I think the problem with these systems if you do not meet the classical 2growbed litres to 1 fish tank litre, is more that when you get to high fish loadings you have trouble take out the nitrate with your plant growth. So you have to stock heavy feeding plants at high densities t make up for the less volume of growbed.

This could be as simple as adding an NFT system at your peak growing times and using water that has come out of the growbeds so it has been filtered, and growing lettuce and silverbeet.

any way hope this helps, Nick

[Jim Bedford]

Hi Folks,
I'm following this thread with interest and am a little confused. Jim has growbeds @2x1x0.4m=0.8x8 of=6.4m3 =6400L minus the scoria or other media displacement. Sorry, I'm a bit slow on the uptake here, and not in a rush, so am doing as much research as possible. Nick, how did you arrive at 4000L growbed?
Thanks for your patience and advice (and these sites you find, Hamish, are very interesting, Cheers)
Jim Bedford

[Murray]

The volume of fish tank to grow bed is just that, the total volume. The volume is not talking about the water volume in the grow bed, but the total volume of the bed, media and water. You don't need a bio filter ...as posted above by Nick, FF and Hamish, but it does help and is a bit extra insurance to help balance the system. I have a canister positive pressure bio-filter that I shift from fish tank to fish tank when I need a bit of extra filtering for what ever reason. Very handy, but not strictly essential.

[GaryD]

Hi,

Just to weigh in with my two bob's worth......the 6400 litres of grow bed is perfect for your 4500 litre tank.

As others have suggested, you won't need a bio-filter for this system.

Gary

[nick]

i just made the assumption that they are roughly the same as murrays and they are 500l each, thus the 500 X 8 gives 4000litres, the calcs were off but the thought is still the same.

[CQ AQUA]

Cheers guy's. Thanks for the info.

So many ways to achieve a result and only so much yard to use. :)

Thanks again everyone. Starting the install process in the next few weeks, will take a while to construct it all but cant wait.:D

[Marilyn]

Hi everyone, Im just a bit confused:confused:. I'm still in the process of setting up growbeds. We started with 2000lt tank with 54 jade perch and have not lost any. They are growing nicely and most are over 150g with some topping 200g since getting as fingerlings on the 1st Feb08. We have not as yet got growbeds in place as I said earlier but want to know why to put biofilter before growbeds, is this to stop sediment blocking the pipes? I thought the plants would require as much of this as possiblr or is all the requirements dissolved in the water. We have a bought biofilter running constantly on the tank but I want to have a go at making my own. I have found a design on the internet that sounds easy to put together using just green scourers. The water that the fish is in at the moment is very brown and impossible to see the bottom. The fish seem happy though and water tests are in a good range. Hope to have system up and fully running in the next month or so. Off to bunnings now to see what goodies I can get for my filter.
Appreciate any advice, Marilyn

[Hamish]

I dont fully understand the need to filter the water prior to it going into the grow beds.

Perhaps over a long time the solid waste might build up in the grow bed and create anerobic zones - which is not good for water quality.

My water just goes strait into the grow bed. I am sure the worms I put into the grow bed will be apreciating any chunks that go into the grow beds with the water :)

Many people seem to run like this without prefiltering and without problems.

Time will tell if my system runs ok as the fish grow.

[djs-sa]

hi I have made my own bio filters with a black tub filled with bio ballsthen a layer of oyster mesh then dekron another layer of oyster mesh and i have made a 19mm water grid to evenly disperse the water and to get to correct flow also. finally the lid on top is zip tied into place to stop any water escaping out.

[Murray]

Hi, You do not need a pre bio filter as the grow beds are the bio filters, but having said that, a bio filter will not cause any harm. I am sure I have posted about this before but I use a pressure canister type bio-filter to clean up the water a bit more on individual tanks where ever needed. Sometimes if I over feed a bit or I top up a tank with dam water I use the bio filter to quickly clean up the water.
If your main interest is in growing the fish then a pre bio filter is a very good way to make sure the water quality is just that little bit better without the need to add more grow beds.....or another way of looking at it , a pre - bio filter will allow you to carry a slightly higher fish load in a given tank.

There are many ways to "do" aquaponics. The good old gravel grow bed is simple and reliable, but if you want to push the envelope a little then additional bio-filters are a great addition to a system

[GaryD]

Hi Marilyn,


We have not as yet got growbeds in place as I said earlier but want to know why to put biofilter before growbeds......
If you don't have grow beds in place, I would (as a matter of urgency) set up a trickling bio-filter. From my reading of your post, it seems that you are relying on a small canister filter (or similar) and my concern is that it will not meet your nitrification needs as your fish grow.

A tricking bio-filter is easy to make......a plastic drum filled with media (we use oyster shells) positioned alongside the tank at a height where the water can drain from the bottom of the bio-filter back into the tank.

When you set up your grow beds (which are also bio-filters) you won't need this trickling bio-filter but (as Murray has already said) it won't do any harm to leave it in the system.

I do recommend trapping the solid wastes before they hit the grow beds because grow beds (like any bio-filters) function micro-biologically better without them. These wastes are most easily removed by a piece of filter foam or dacron that is rinsed out at regular intervals.

We rinse the solids out and pour them into our worm farm. In the process of being turned into castings, the solids are mineralised. From time to time, you can take a handful of castings and place them in an old sock and soak them in water.

You then pour this water back into the fish tank and, in the process, you re-introduce the nutrients in the fish solids back into the system.

Processing the fish solids in this way will allow your grow beds to function more effectively and are cleaner to work with.


I have found a design on the internet that sounds easy to put together using just green scourers. The water that the fish is in at the moment is very brown and impossible to see the bottom.
I've seen some of the designs that you're talking about and, if I recall correctly, they are submerged filters. The good thing about submerged filters is that the drum can sit alongside your fish tank (rather than on a support platform). While they will work OK, you'll need to make a substantial investment in scourer pads.....and submerged filters don't aerate the water as effectively as trickling bio-filters.

Gary

[Jonathan Dyer]

What is dekron? Is it another name for noodle mats?

[Murray]

Dacron is a cotton wool like product commonly used as the internals of a bed quilt for example, or as the inner of a sleeping bag.
Makes a good filter just like cotton wool would, but is easily able to be washed out and reused.

[Marilyn]

Hi everyone, thanks for your input. I replied earlier but for some reason I lost the message as I submitted it.

Gary I thought the scourers may be expensive but a couple of weeks a go Bunnings had them on special for 50 cents a bundle so not passing a bargain I grabbed some knowing that eventually they would be put to good use. The rest of what I needed came in under $60. I already had a spare pump so that was a bonus. Yes it will be set up above the tank and splash back in.

I saw a similar setup at the Nambour Garden Expo for $895 so I'm well in front.

[Marilyn]

Hi Gary,
Here is a link to the system I found to make the filter.http://leisure.prior-it.co.uk/build-diy-pond-bio-filter.shtml

[Hamish]

Hi Marilyn - would be good if you could show us all the steps in photos as you build your biofilter :)

[djs-sa]

have a look at the size of that pot in the link! hope urs is going to be bigger than that! what size tub will u be using to hold ur media? and that will depend also on ur media's surface area.

[Marilyn]

Hi everyone, the filter is made and just waiting for the silicone to cure overnight before I check to make sure it is water tight. It took about half an hour to cut and put together. The pot I am using is about 60 litres so for a trial is adequate for what I want at this stage.:)

[DaveOponic]

Up until now I have only used clay balls with a charcoal base in my grow beds. I split a 200 litre PVC drum lengthways with a wooden frame to support the drum.

Now my fishies are growing bigger, I need to think about a bigger tank (Maybe 1500 litres) and some bigger deeper growbeds.

The cost of BBQ charcoal and clay pellets would be prohibitive so I am thinking of using gravel. Here in Brunei, aquarium gravel is expensive and I haven't discovered any free source except "blue metal" left over from road making or sold by hardware suppliers for mixing concrete.

Can anyone advise me about using blue metal? I would use this as the base and probably a finer aggregate in the top layer and clay balls for the top "soil".

Also can anyone comment on whether flood and drain is better than a trickle or spray system in large growbeds? My present growbeds use PVC pipe around the perimeter with small holes drilled several cms apart that spray a trickle of water onto the clay balls. I previously tried a flood type system but found the balls floated in the water and the seedlings weren't supported. I guess this is a big advantage of using gravel... it doesn't float.


Dave

[Jim Bedford]

Hi Dave,
I'm a few weeks away from settimg up my system here in Nthn Victoria, Australia, but I wonder whether putting fine aggregate onto blue metal would be wise. The finer material will eventually work down to the bottom and cause problems. I seem to recall Murray mentioning 20mm as an optimum size.
Also, I've been interested in your use of BBQ charcoal. I make manure 'teas' for my in-ground veg, and am concerned at the increased concentrations of agri-chem/pharmaceuticals and the potential for their up-take by annual plants. Charcoal can filter these out, until the pores become saturated, at which time the charcoal needs to be replaced. The only problem is the bonding agents in BBQ charcoal. I can't find specific info as to their composition, but it's inferred that they're not benign. Does your charcoal list its ingredients on the bag?
Cheers
Jim B