Do I need a Biofilter for my aquaponic system? Yes, in aquaponics a biofilter is used to filter bacteria to turn the ammonia from your fish poop into plant food. Microorganisms consume the waste and excrete nitrites and finally nitrates.
Even with the most basic of research into the aquaponics world, it can be hard to avoid the word: biofilter. But what exactly is a biofilter and do you need one for your aquaponics system?
We’ll explore what a biofilter is, how and why they work, as well as when one might be necessary.
I’ll also be giving you the basics on how you can set up your own for surprisingly little money with stuff you already have at home.
Using a Biofilter in an Aquaponic System, an Inexpensive Filter that Converts Impurities into Nutrients
To put it simply, everybody poops, and that includes fish. Regardless of how packed your tanks are, all that waste can add up pretty fast.
If you’ve ever accidentally put too much fertilizer into your garden, then you know how easy it can be to overfeed your plants.
The biggest problem with fish waste is that it contains high amounts of ammonia. As the most toxic form of nitrates, ammonia can burn the roots of your seedlings.
Even more mature plants sometimes struggle to convert too much raw material into useable nutrients.
That’s where your inexpensive biofilter comes in our aquaponics system.
Your plants can then take these digestible nutrients and grow faster than any soil based system can boast.
Why/How: Use Large, Porous Surfaces to Grow Better Bacteria in a Biofilter
What makes or breaks a biofilter isn’t the size of its container or how much money you spent on it, it’s the material inside.
Much like choosing a good growing medium for your plants, choosing the right materials for your biofilter makes all the difference.
Popular commercial options include things like ceramic media, biofilter balls, and floating bio-media.
Much like ceramic grow balls, ceramic bio-media is a popular choice among aquaponics enthusiasts.
They come in a variety of shapes and sizes, but one thing they all have in common is a porous surface area and good water absorption. Porous allow better bacteria growth.
They do best in static systems and are fairly affordable for the home grower. That said, they’re often far too heavy to float and can be more expensive for larger operations.
Inexpensive biofilter balls are plastic spheres designed specifically for biofiltration in aquaponics.
Instead of a smooth surface, the ball is made up of ridges to allow plenty of space for bacteria to colonize.
Biofilters are fairly cheap, incredibly effective, and can be found online or at your local aquarium store. They can, however, be a bit more difficult to find in bulk.
Aquaponics in its self is a biofilter. The sides of the tank and grow beds will create a biofilter effect.
One of the best options out there is a small, almost pasta looking floating bio-media.
While they come in many brands, these little tubes easily stay on top of the surface and work well in a moving filter system.
Ridges combine with a wheel style, hollow center to allow the maximum colonization of your microorganisms.
In a sense, all those little nubs and holes allow bacteria to grip and flourish in a biofilter. They’re inexpensive, don’t affect the PH of the water, and are readily available in bulk quantities.
Higher Density Systems Needs Higher Filtration
There are a lot of factors that go into deciding if your aquaponics system needs a Biofilter. The first consideration of whether or not you need one is your grow media.
If your plants are floating on styrofoam, they aren’t going to have the same bacteria colony of a grow bed filled with lava rocks.
Vertical systems in PVC tubes also struggle with the proper surfaces for microorganisms to latch on an grow.
In cases like these, a biofilter is necessary to ensure the maximum output and health of your plants.
Another instance where a filter can be extremely helpful is if the fish in your tanks are stocked at a higher density.
The more fish there are in the tank, the more waste they’ll produce and the more help your system will need to thrive.
But if your setup has abundant quantities of a porous growing medium and your fish have plenty of room to breathe, a biofilter isn’t going to be necessary.
Use Less Expensive Household Items for a Less Expensive Filter
If you do decide that a biofilter would suit your operation well, then you don’t need to spend an arm and a leg on commercial bio-media and high tech systems.
A cheap cooler, five-gallon bucket or rain barrel with ports drilled into works well for most operations. But really, any container that’s clean, free of leaks, and has a lid can be used.
That includes a five dollar Tupperware from your local supermarket. All you have to do to get it ready is drill holes for water to go in and out.
Just like with your container, your filter media doesn’t have to be expensive or complicated. Netting, chopped up kitchen sponges, and cut up straws are all inexpensive solutions that give bacteria a large surface area in a biofilter.
Sterilized rocks and bottle caps are also more than useable and likely something you already have laying around your home.
Add in the $20 to $60 most people will spend on a simple water pump and you’ve got yourself an inexpensive, upcycle biofilter.
Feed good food
If a biofilter isn’t something you’re interested in building or buying for your system, then it’s important to use the right food.
Overfeeding fish will lead to bacteria in the system, a biofilter will help dispose of extra food.
It might sound like a hassle to have to research into a species appropriate diet. It might even cost more, but all that investment will save you money in the long run.
A lesser quality pellet is going to be far less digestible, and you’ll need to feed more of it to get the same growth rate.
It’s also important to remember that even if your fish actually eat all that extra food, what goes in must come out.
Once it’s been digested, poop that’s made from a low-quality food isn’t going to break up into tiny particles as easily.
It’s very likely you’ll still find bits of undigested pellet polluting your water quality anyway. Invest in quality diets, and you can lessen this problem.
Don’t Overfeed the Fish
In that same school of thought, try not to overfeed your fish. You could buy the best food in the world, but if you’re feeding too much they aren’t eating it all, that food is going to fester in your tanks.
Free-floating food can clog up your filters and mess with the quality of your water.
Feeding only what your fish need will help keep your water clean and lower the amount of ammonia your fish produce.
Less ammonia means your aquaponics system or even your aquarium will need less help from you to keep itself healthy.
Bacteria Needs Air too Breathe
Another thing to keep in mind is that it’s not just your plants or even your fish that need air.
The bacteria that work so hard to keep your crops growing needs oxygen too. Adding an air stone or two into your system can help breathe in the life it needs.
But what if you don’t want to spend any extra on electricity? At the same time, some kinds of fish can’t tolerate a high oxygen environment.
In these cases, you can set up your water pump to tumble over a porous growing medium like lava rocks.
The constant motion of the water over your plants should help give your microorganism colony the air it needs.
You do not need a biofilter in your aquaponic system but I recommend it. Any surface area will start the bacteria in a biofilter metals will take a longer time.
Aquaponic has a few inexpensive filter systems, biofilters are one of my personal favorites
Remove Solids First with Biofilter
Whether you decide to use a biofilter or not, it’s important to remove solid waste from your grow tanks. Fish produce a surprising amount of waste, and leaving it in the tank can quickly sour the water.
Pumping solid waste through the system along with your ammonia-laced water, will only tax the filter and cause it to gum up.
Make sure the pipes taking fish water to your filters and plants are outfitted with some kind of screen to help keep your system from clogging up.
So to recap, a biofilter is a filter that uses microorganisms to convert the impurities in a fish’s water into safe, useable nitrates for your plants.
A large surface area with healthy levels of oxygen does wonders for this bacteria colony. Use a biofilter to help out systems that have low amounts of growing media or heavy quantities of fish.
Rather than spending a fortune on pre-made filters, you can easily make your own at home with items you already have sitting around your house.