Author Topic: How bios effect my tank and how biological filtration works!  (Read 779 times)

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Offline Hood

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How bios effect my tank and how biological filtration works!
« on: April 02, 2010, 08:38:27 AM »
I have noticed that there are many people who try fish keeping, just to dismiss it as too hard, because their fish keep dyeing. Usually because they don't understand the basics of bios in their tanks. So with the help of many resources including discus forum, I have put together this article:

how bios effect my tank and how biological filtration works?
The enlightenment of poo, and its eventual transformation into a new state of being.

Many people I speak too, tell me they have gotten into fish-keeping only to realise that they got into a hobby which is actually a lot more complex than they realised!

The general consensus seems to be that they lose a lot of fish by:
  • not having enough understanding about how fish keeping works,
  • not having enough or any help when things go wrong,
  • and not having enough or any basic sources or resources to draw from when in need, or just curious.

In the process of learning many of us may lose a lot of fish. Often expensive ones. Which 'causes many us to freak out, tear out our beards, gnash our teeth, and yell about what a crappy hobby fish-keeping is!!
Then feeling completely frustrated and disappointed, often they just give it up... which is always a great loss to the fish-keeping community, as we want to grow our hobby!
Biological filtration and how bacteria works in your tank is probably one the most grassroots principle in fishkeeping, and without doubt the most important to understand.
The vast majority of filtration systems for aquariums these days, utilise biological filtration as their main solution for converting harmful waste products such as ammonia into less harmful ones like nitrates.
However, there are certain conditions in which biological filtration will not work, we will get to this later.

In tanks that have been setup to house discus, angels and other community tropicals, the proper conditions should be ideal for biological filtration.
The pH should be around 7 and the water should be reasonably soft.

When any of us are setting up a new tank, a running-in or "cycling" period is needed before introducing fish to the tank. This generally takes 4 - 6 weeks.

Here's why:
When we start a new system there are very few microscopic organisms living in it.
Usually we use tap water which has been chlorinated, and a lot of bacteria and micro-organisms die from chlorine poisoning, including the good bacteria which is active in biological filtration (poor little guys, but luckily for us it kills all the nasties, too.

Although, who knows what our consuption of the chlorine in tap water, does to us on a daily basis). So obviously to start off with the
tank is quite sterile. So we need to kick the nitrogen cycle into gear!

The Nitrogen Cycle uses two species of bacteria, which will form in specific sequence as the system begins to 'cycle'. The first of which to appear is the Nitrosomona bacteria.
Fish generate a lot of waste(poos and wees), which is quite high in ammonia content.
So the first stage in biological filtration and building bios in our tanks is for these handy little Nitrosomona bacteria to consume or eat the ammonia and convert it into slightly less harmful nitrites. This is very important, because ammonia, even in relatively small amounts in our tank water is quite a deadly substance for our fish. Nitrites are somewhat less toxic, but they are still very dangerous if larger amounts occur in your tanks water. It takes about 1 to 3 weeks for this to begin to happen effectively, but our clever little bacteria do not finish there.

After our 1-3 weeks of our Nitrosomona building stage, our tanks will then enter the second stage of biological cultivation.
The second stage of biological filtration will kick in, once there are enough nitrites present for our second type of bacteria to thrive on. These hard little workers are called Nitrobacter. Nitrobacter consume or eat the nitrites and convert them into relatively harmless nitrates. This process takes another 2 to 3 weeks to occur naturally in our tanks.

Both of these bacteria are of a type called "aerobic"(which doesn't mean they dance around a lot and play silly music), it does however mean that they require oxygen to function.
There are many different ways to oxygenate your water effectively, but that's another subject(see article on aeration and airstones:

Traditionally, the best way to cycle your tank, was to purchase a couple of cheap fish (guppies, feeder-goldfish), that can be used to start the Nitrogen Cycle utilising their waste products.
However there are some enzyme based products on the market available at most Local Fish Stores, which can be used to "kick-start" this cycle. With these methods the cycle time is cut down quite a bit.
Here is a good link if you want to learn about fishless cycling :

Another good method to cycle your tank, is to use some of the media from an already established filter, from an already established tank, alongwith water from established tanks.
If you do happen have multiple tanks or a friend who will give you some established filter medium, you are very lucky! As you can start your tank straight away, with this already established medium and water!
But be quick in getting this into your new set-up, as the bacteria will begin to die within 1 - 2 hours, unless kept both moist and in contact with air.

In nature the end product of all this hard work are nitrates.
And as we all know, plants use nitrates in their growth process, and heavily planted aquariums with very few fish in them can be balanced, where the plants use all the nitrates present in the water.
Though this often isn't practical in most discus/cichlid tanks however, as many are bare bottomed, or have no plants, or both, and have
too high a population of fish for this to be viable. This is why we do water changes, as often and conscientiously as we can.

Although these nitrates are a lot less toxic than nitrites or ammonia, it still builds up in our systems and will pose a problem to our fish. Especially to those fish like discus, tangs and any other fish susceptible to poor water quality related illness.

So change your water regularly, at least 30-50% once every 1-2 weeks, your fish will love you for it. They will will be happier and greet you whenever you come into the room.
Examples of filters using biological filtration include:
  • under-gravel filters,
  • fluid-bed filters,
  • canister filters,
  • hang-on filters,
  • trickle-filters,
  • sump filters,
  • sponge filters,
  • box filters,
  • top filters,
  • power filters etc, etc

As mentioned earlier, there are conditions of extremes where biological filtration becomes non-functional, as the bacteria cannot survive. One such instance, is the condition in which blackwater fish need their tank kept, such as the condition some Apistogramma species need to spawn. This water can be as low as 3.5 pH and have extremely low, if any, hardness at all. Some species come from water so soft and acidic, it rivals Reverse Osmosis filtered water!!
Such extreme acidity will not be conducive to the survival of bacterial cultures in a biological filtration system and so we are back to many, many, water changes (did I mention your fish will love you for those?!? and maybe, if you're really, really, lucky. They just might get the newspaper for you in the morning and your flippers, too! But you have got to be very lucky).

One word of advice on stocking your tank. When the biological filter is set up, try not to dump 50 Ga-gillion fish into your tank at once, as this will very quickly overload your newly created bios. I would Rather,instead, increase the load slowly and steadily, and that will give the bacteria the much needed time to increase their consumption rates, as the waste products increase.

Hope this helps,
enjoy your fish, ;D