Don’t let anyone tell you undergravel filters can’t be an effective filtration option for your tank.
When done right, they can be POWERHOUSES for stabilizing a healthy aquarium.
The traditional undergravel filter setup method is straightforward:
Plates on bottom.
Gravel on top.
Water pulled down into the gravel bed.
There are some pretty major drawbacks to this setup (which is partly why they have fallen out of favor in recent years).
I’m not saying never ever do it this way or it’s the end of the world if you do.
But I think there are some better ways that will make your life easier and keep the risks down for your fish.
Fishkeeping should be as simple as possible.
So today I’m going to share the top 2 ways to set up an undergravel filter that overcome both of these problems – and make your biological filtration MUCH more efficient in the process!
- Related Post: Do Goldfish Need Gravel?
Table of contents
How to Set Up a Safer, Easy to Clean Undergravel Filter for Your Fish Tank
I’m giving you the 2 best methods I know of.
There may be others I haven’t tried that are just as good or even better.
Don’t be afraid to get creative and experiment if you want.
For what it’s worth, I really like the Penn Plax line of undergravel filters as they can be customized to fit almost any dimension of tank.
You can also piece together several smaller sizes if your aquarium has a unique footprint.
Whatever works for you.
You can use the setup designs below alone or in conjunction with another kind of filter.
The Sand Cap Method
This is idea combines the benefits of sand (does not trap muck like gravel) with the efficiency of undergravel filtration.
I recommend using CaribSea aquarium sand, the Crystal River style.
Out of all the sands I’ve tried, this one works the best.
The grain size is much larger than average sand but still small enough to prevent fish choking while having the debris sit on top, patiently waiting to be vacuumed.
One big advantage of this method is you don’t have to deal with plants rooting in the filter plates, which is a big problem for growing plants with traditional UG filter setups. Due to the strategic placement of the polyfiber barrier, this method is ideal for keeping rooting plants.
I highly recommend adding some heavily rooting plants as it will keep the substrate aerated and help lock down the gravel-type media under the sand for those with digging fish.
Not all plants enjoy soil aeration, but some like Amazon Swords really do.
The roots cannot get through the barrier and block the flow – but the water can.
The barrier is not thick enough to serve as mechanical filtration, and even if it were it is far down below the layers of sand and gravel-type media. This means it does not need to be replaced continually.
Most UG filters come with little carbon inserts you can put on the tips of the uplift tubes.
If you’re like me, you find this unsightly.
Part of why I love Undergravel filters is because they are just about invisible, and I don’t want distracting little black squares in the tank (third world problems, right?).
So where do you add other kinds of media (maybe Phosguard, Purigen, Algone, active carbon, or otherwise?)
With this particular setup it isn’t really that easy – as in, pretty much impossible – to push aside all the stuff on top of the filter plates and bury your packets of chemical filtration like it would be with a regular undergravel filter setup.
And if you have plants rooting – forget about it.
But there’s a workaround:
I use this little internal power filter just big enough to put my chemical filtration in, stuck behind a rock and plants. It doesn’t have to be huge, as it’s not functioning for biological filtration (you are more than covered on that!).
Yes it gives you another black cord to deal with, but hopefully your tank is planted enough that the stems and leaves can conceal it.
The Reverse Flow Method
Reversing the flow has some major advantages (source).
Here’s how to do it:
It’s a good idea to supplement this method with an airstone, sponge filter or HOB filter for aeration and surface movement.
Connect it to a canister filter packed with mechanical filtration media to purify the water first before it sends the flow down the UG filter tubes from the outlet.
Hello, sparkling clean water!
Advantages of Undergravel Filters
Annoyed by loud sputtering, gurgling, trickling or dripping from other kinds of filters?
The only noise just about will be coming from your air pump vibrating (if you use one).
If you work in an office or want a quiet tank in your room this can be a big perk.
Just about every filter out there is an ugly intrusion into your beautiful aquarium scene.
There’s almost no way to totally hide most of them.
With Undergravel filters, you integrate the filtration so closely into the aquatic environment there is almost no transition.
Huge biological footprint
You can’t beat the surface area the size of your aquarium’s footprint.
End of story.
Prevents bad anaerobic forming in the substrate when set up using the methods described above – score!
It’s okay to go heavier on your layers of substrate since you are getting oxygenation happening.
I hope this post sparked your interest in the possibilities of filtration with undergravel filters.
What about you?
Have you tried them, and what have been the results in your tank?
Featured Image Credit: PDPics, Pixabay