The Biological Waterfalls

At the top of this waterfall behind the rocks
is the waterfall unit -- filtering while disguised!

Every waterfall on the ponds at our store or our installation customers' ponds have biological waterfalls. Not only is that waterfall the building block of creating a natural-looking, beautiful waterfall, but it's the main source of biological filtration and also does some mechanical filtration as well.

This is the expanded view of one of our waterfalls. The third layer from the top is
a media bag which would hold either the bioballs or lava rock.

What is biological filtration on a pond?

If you have a pond, you most likely know or have heard the term "beneficial bacteria". There are many strains of beneficial bacteria and each has its own job. Basically, some of the bacteria take waste and turn it into plant food. The waste comes from fish, decaying plant materials, uneaten fish food, etc. Other strains then compete with algae to eat the "plant food."

Here's a general look at the nitrogen cycle that's happening in your pond (described above).

When you see a pond that has pea-soup green water, that is caused by single-celled algae floating in the water. That pond doesn't have enough or the right strains of beneficial bacteria to consume the nutrients in the water, thus feeding the algae.

Biological filtration is all about growing that beneficial bacteria. Biological filtration is housing for lots of great bacteria to keep your pond looking clear. 

How do beneficial bacteria and the waterfall relate?

Beneficial bacteria do float through the water, but they really need surfaces to adhere to so they can reproduce. That's where the waterfall comes in.

This biomedia is called "bioballs" and it sits inside your biological waterfall to grow bacteria.

Inside the waterfall is lots of filter media -- layers of filter mats and either bioballs* or lava rock. The filter media is the main area where the beneficial bacteria will colonize. As the water passes through the filter media before falling back into the pond, all that bacteria is doing its job cleaning the water! (Make sure the filter mats are the lower level of filter media and the bioballs or lava rock are on top -- important!)

*Bioballs are plastic media that hold lots of colonizing bacteria. They are better than traditional lava rock because unlike lava rock it never needs replaced and is extremely light weight.

What about mechanical filtration?

Mechanical filtration is the act of pulling debris out of the water. If you have a skimmer, it is your main source of mechanical filtration.

However, those filter mats in the waterfall are also pulling out the fine debris that passes through the pump and skimmer. And if you have the right type of waterfall, you have a debris chamber in the bottom of the waterfall. What's a debris chamber? On properly designed waterfall units, the filter media is raised above the bottom of the waterfall and there's an open area below it. That open area is the debris chamber. As the water enters the falls in the bottom, it swirls around and debris which is heavier than the water drops to the bottom of the chamber and is kept out of your pond. Awesome!

Sizing the waterfall

You can certainly under size or over size a waterfall. If undersized, of course it's not going to filter the water efficiently. You also don't want to install a waterfall too large -- it can be harmful to your fish. Your pond size and pump size will determine what size works the best for your pond. We're happy to size a waterfall for you!

Cleaning your biological waterfall

When it comes to a biological waterfall, the dirtier, the better. Only clean it once a year in either the spring or fall. 

All the gunk on the left side of this filter is good gunk! That's bacteria!

Why? Because you kill all the bacteria when you clean it! This is important. Let it be and get nasty. It's ok! When you do clean your waterfall, make sure to get the beneficial bacteria started again with BioClear and Clean. You should actually be using BioClear and Clean on a regular basis to keep bacteria levels constant.

Biological waterfalls can be added to existing ponds. If you already have a biological waterfall that's not doing its job it can be replaced. If you could only change one thing about your pond to make it function better, this is what we would suggest. Need some help with your waterfall? Let Cool Ponds help.