Aquaculture Biofiltration:  A pollution control technique using living material to capture and biologically degrade process pollutants. Common uses include processing waste water (toilet and kitchen sink water) and closed ecosystems, aka. recirculating aquaculture systems (RAS)  (a fancy name for man made ponds and aquariums).

I decided to devote a section of my site to biofiltration due to the many possible applications it has, (not to mention the endless hours of my life devoted to it that I'll never get back)..

Below is the end result of endless hours of research, experimentation, and study. In fact I carried my research as far as I could without buying expensive microscopes (I have a few cheap ones), fancy lab equipment etc. I'll save you all the scientific terminology, calcualtions, etc. and try to explain this biofiltration system in terms everone reading it can understand.

I recently became a LEED AP (Acredited Professional). Which means I know a little bit about making environmentally freindly buildings. We also have pet turtles living happily in our living room ponds consisting of several hundred gallons of water. This water is where our six turtles eat, pee, and poop. And believe you me, they eat, pee and poop a lot. Pound for pound, turtles produce six to eight times more bio-waste than fish. Due to proper biofiltration, we change the pond water out about once a year when we perform general maintenance on the entire turtle ecosystem. Without the biofilters we would be changing the water and cleaning the ponds every three or four days.

Keeping turtles or any reptile is not easy, and I do strongly recommend against them as pets. These are wild animals that are not domesticated. They are cold blooded and extremely 'enviroment sensitive.' In the wild they are free to go where they need to go, and do what they need to do to live happily and be healthy. In captivity, they are at your mercy. Though your heart may be in the right place and you love your reptile dearly, if you don't know what you are doing, especially with an aquatic reptile, you will cause your reptile to be sick, suffer from many painfull infections, malnutrition and a premature death. I have spent a lot of money on vet bills, and a good exotic pet vet is extremely hard to find. That  being said, if you have or want to keep a turtle or turtles, knowing how to build a biofilter is critical to a successful  experience.

The Classic Plastic Paint Bucket Biofilter.
All parts and materials were purchased at Home Depo and Target.
The total cost of  materials was under $10 dollars in May of 2008.
(Excluding the tubing and the magnetic-drive Pump.)

free had sketch of Paint Bucket Filter

If you have a man made pond or aquarium, many things are going on in the water, especially if you have fish, turtles, frogs or other life in the pond. Chances are you do not have a system large enough for mother nature to balance things out on her own and you need to give her a helping hand.

Let's have a quick and very over simplified lesson in what happens in nature.

Phase One:
In nature, animals pee and poop a lot. In addition, plants and animals live and die. Think of pee and poop as dead animals and plants that have already been 'processed' by nature just a little bit. All of this aforementioned 'stuff' is organic material. In nature, non-living organic material rots and decays. This rotting process is performed by oxygen breathing bacteria that eat the organic material, breaking it down releasing their own form of pee and poop, which is primarily ammonia. The bacteria that causes organic material to rot exists all over in nature. It can move around and live independently in water, soil, air, etc. Many types of bacteria that do this but I said I would keep it simple so think of this bacterium as falling into two basic types; good rotting bacteria and bad rotting bacteria. We want good rotting bacteria and we need to be on constant look out for bad bacteria. Please note even the good bacteria will eat living things if there is not enough dead organic material, but more on that later.

Phase Two:
Ammonia is poisonous to all living things if it is in high concentration. In nature, ammonia is consumed by another type of oxygen breathing good bacteria, which turns it into another substance us science nerds call Nitrite. Now Nitrite is still poisonous in large quantities, but not as poisonous as ammonia (go figure). Now the oxygen breathing good bacteria does not move around, but rather the forces of nature randomly shove it around until it finds a nice place to call home. This place ideally is rather rich in ammonia with not a lot of the rotting bacteria around. (As it turns out, the rotting bacteria like eating the ammonia-eating bacteria.) Once it finds a good place to call home, it starts to reproduce itself into loosely linked strands of bacteria so that it doesn't get lonely. Every now and then a few bits of the ammonia eating bacteria breaks away from this new home to go find another place to live, etc.

Phase Three:
In nature in case you haven't guessed, there is another type of oxygen eating bacteria that eats Nitrite and turns it into an almost harmless and interesting chemical called Nitrate. (One of the fascinating things about the universe is that whenever God sees a good idea, she tends to use it over and over.) Like the bacteria in Phase Two, the Nitrite eating bacteria does not swim around, but lives much the same way as the Ammonia eating bacteria. Now even Nitrate can be toxic in large quantities, but Nitrate is 'plant food.'

Phase Four:
Plants love Nitrate. Though not as toxic, high levels of Nitrate can cause algae problems or to much plant growth. Therefore, to get rid of Nitrates there is yet another type of good bacteria that eats Nitrate, and believe it or not, does not breathe oxygen! When it eats the Nitrate, it produces Nitrogen gas and a few other harmless things. This Nitrate eating good bacteria is hard to cultivate. It doesn't move around, and oxygen is everywhere. Another way of getting rid of Nitrate is off gassing it by creating turbulent water i.e. running water swiftly down a water fall or gurgling stream etc.

What I have described above is called the 'nitrification cycle' and the 'denitrification cycle.' there is a plethora of information on the 'World Wide Waste-of-Time' and in librariues, text books, etc.

Getting back to the Filter...
I have built many filters and as long as a few basic rules are adhered to, they all will work just fine. This is by far the cheapest and easiest one I have done and it works just as well, if not better than others do. Ok, what we need to do is mimic nature, but we need to do it in such a way that it doesn't break the bank. The filtration starts at the bottom of your pond or aquarium. The pump and intake filter can be bought at Home Depo. The organic material is caught in the filter material and as the water is pulled into the filter, the organic material is broken down and sucked into the pump. The pump delivers to the 'Top filter' a well blended, pee, poop, and food 'smoothie.' This intake filter also becomes home to 'rotting' bacteria. As long as the pump is running this is where it will concentrate in the pond, because this is where the bulk of the non-living organic matter will be.
 Please note that without the intake filter, you will need a much larger pee-poop-food smoothie compartment. A good portion of the phase one dacaying process is taking place at the intake of pump.

The 'smoothie empties from the tubing into the first chamber #3, which in this case is a large plastic drinking cup. the cup is filled with either plastic 'whiffle' golf balls  or somthing similar. this breaks up the flow of water and causes ''dead zones'' in the water  flow for the solid waster material to settle out. In the cup there are lots of thin knife cuts for the water to seep through. Granted, some of the soild waste will get through as well but as you cycle water through the filter this fist compartment is where the solid waste will congregate and the rotting bacteria will predominantly preside.

The organic material will continue to break down and also seep through this compartment to the Item two which is a plastic gallon paint bucket willed with 'angel hair' filter media.' The angel hair stuff seems to work the best, however the first mistake people make is to  pack it in there to tight. When suspended in water this stuff spreads out and a little bit goes a long way. On the other hand, not enough and your bactertia colony will take a very long time to form and be very fragile. The filter media is not being used to actually filter, but to provide a nice home for the Phase Two ammonia eating good bacteria to grow and be happy.

Resting on top of the #3 compartment and underneath the lid is a pad filter. this can be bought at a pet store and cut to size. this helps a bit to keep things contained in compartment #2. Granted you can't keep the bacteria from moving around. All you can do is set up places where it will 'prefer' to be. 

In the lid of compartment #2 put a few holes near the center or even just one hole. the opening should be no more than double the area of the tubing feeding the filter.

It's time to make the donuts! .....I'll add more later .... 

Copyright  August 23, 2008. Kenneth E. Chappell , All rights reserved
All works produced by Kenneth E. Chappell may not be used or reproduced without written permission.

Further info on bacteria and along with water
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