How To Make An Undergravel Filter

It's A Fish Thing is reader-supported. When y'all purchase via links on our site, we may earn an affiliate commission at no cost to you. Learn more than.

Look:

Don't let anyone tell you lot undergravel filters tin't exist an constructive filtration option for your tank.

When done right, they can be POWERHOUSES for stabilizing a healthy aquarium.

Granted:

The traditional undergravel filter setup method is straightforward:

Plates on bottom.

Gravel on superlative.

Water pulled downwards into the gravel bed.

BUT…

There are some pretty major drawbacks to this setup (which is partly why they have fallen out of favor in recent years).

Gunk gets trapped in the rocks and under the filter plate. Non but is it difficult to clean, only actually, this can be a very unsafe problem – especially if not cleaned very frequently. As in, all. The. Time. These pockets tin can go anoxic and nasty disease-causing bacteria can form in these areas, leading to sick fish. Fifty-fifty if you lot vacuum out the gravel frequently, yous still can have all this droppings lodged under the actual plates that can't come out without a deep cleaning – sometimes necessitating a tank tear-downwards.
Modest gravel poses a choking hazard for some fish similar goldfish. Bigger or adult goldfish especially are prone to getting "rockitis" where the gravel actually gets lodged in the back of their throats, blocking their ability to consume and causing other symptoms similar lethargy and strange mouth movements.
Difficult to grow plants in directly. Plants can grow roots into the filter plates and restrict the water menses through the filter, destroying the effectiveness of your filtration. If you want rooting plants information technology'south recommended to keep them in something like a glass institute jar.

I'm not saying never ever exercise it this way or it's the cease of the world if you do.

Merely I think at that place are some better ways that will brand your life easier and go along the risks downwardly for your fish.

My motto?

Fishkeeping should be as simple as possible.

So today I'm going to share the elevation 2 ways to set up an undergravel filter that overcome both of these bug – and make your biological filtration MUCH more efficient in the process!

Related Post: Practise Goldfish Need Gravel?

Table of contents

How to Ready a Safer, Piece of cake to Make clean Undergravel Filter for Your Fish Tank
- The Sand Cap Method
- The Reverse Menstruum Method
Advantages of Undergravel Filters
- Repose
- Invisible
- Huge biological footprint
- Substrate Aeration
Decision

How to Set Upwardly a Safer, Easy to Clean Undergravel Filter for Your Fish Tank

I'one thousand giving yous the 2 best methods I know of.

At that place may be others I oasis't tried that are simply equally practiced or even amend.

Also:

Don't be afraid to go creative and experiment if you want.

For what it'southward worth, I really like the Penn Plax line of undergravel filters as they can be customized to fit well-nigh any dimension of tank.

penn plax undergravel filter

You can also piece together several smaller sizes if your aquarium has a unique footprint.

Any works for you.

Y'all can utilise the setup designs below lone 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.

Why?

The grain size is much larger than boilerplate sand but even so small enough to prevent fish choking while having the debris sit down on top, patiently waiting to be vacuumed.

One big advantage of this method is you don't have to bargain 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 bulwark, this method is ideal for keeping rooting plants.

I highly recommend calculation some heavily rooting plants every bit it volition keep the substrate aerated and help lock down the gravel-type media under the sand for those with excavation fish.

Not all plants relish soil aeration, only 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 fifty-fifty if it were information technology is far downwardly below the layers of sand and gravel-type media. This means it does not demand to be replaced continually.

Identify your assembled undergravel filter plates on the clean, bare bottom of the aquarium.If your tank is already set it is a skilful thought to do a thorough vacuum and water change. You will need an air pump and airline tubing to run the airstones in the filter. I use the double outlet airline pump as yous don't have to T off the airline tubing and y'all only demand to use 1 outlet to run it.
Cutting a piece of sparse polyfiber padding to fit over the surface of the plates. This will ensure no fine debris or sand tin can work their way downwardly underneath the plate and get nasty over time. I used an Imaginarium thick polyfiber pad torn 3 thinner layers and spread them on the filter plates, snipping a slit in the fiber where the uplift tubes connect. It's ideal because the structure allows a lot of water catamenia while preventing sand and droppings from entering. You don't want to employ something that will break down over time, like a cotton textile.
Pour a ane/ii-i″ layer of gravel, pre-soaked Seachem Matrix or crushed coral (for hardwater fish like cichlids) over the polyfiber. This will aid with water circulation every bit well equally provide additional expanse for biological colonization. If you use crushed coral or another porous substrate, you can also provide an area for denitrification (aka nitrate reduction) to occur which would not happen with gravel. On top of this layer (optional just not manditory) yous can identify a layer of mesh or gravel tidy to prevent this layer from intermingling with the sand.
Pour a 1.5-2″ layer of sand over the gravel. If you have digging fish you volition desire to apply nearly 2″ to prevent them from disturbing the gravel underneath.

Some tips:

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 but about invisible, and I don't want distracting little black squares in the tank (3rd world issues, correct?).

And so where do you add other kinds of media (mayhap Phosguard, Purigen, Algone, agile carbon, or otherwise?)

With this particular setup it isn't really that easy – as in, pretty much impossible – to push button aside all the stuff on top of the filter plates and coffin your packets of chemical filtration similar it would exist with a regular undergravel filter setup.

And if you have plants rooting – forget nigh information technology.

Just there's a workaround:

I use this little internal ability filter but big enough to put my chemic filtration in, stuck behind a rock and plants. It doesn't have to exist huge, every bit it's non functioning for biological filtration (y'all are more than than covered on that!).

Yes information technology gives you another blackness string to deal with, but hopefully your tank is planted enough that the stems and leaves can conceal it.

The Contrary Flow Method

Reversing the flow has some major advantages (source).

Here's how to practise information technology:

Place your assembled undergravel filter plates on the clean, bare bottom of the aquarium. No need for the airstones hither.
Pour a layer of gravel or larger porous filter media (such as Seachem Matrix, Pond Matrix which is a scrap larger than Seachem Matrix, or Hydroton). You can also use larger river pebbles, though these may restrict the water catamenia more and won't support nitrate reduction.
Use a submersible powerhead to force water down the uptake tubes. This is what reverses the menstruum and pushes water up through the substrate rather than forcing waste matter down. Pumping water through the substrate upwards keeps information technology free of mulm-buildup, which tin can crusade deteriorating in water quality.
Install a prefilter on your powerhead to prevent droppings from existence pushed by the powerhead underneath the filter plates. This is really a must or you volition cease up having the same problem equally a regular undergravel filter setup.

It'due south a good idea to supplement this method with an airstone, sponge filter or HOB filter for aeration and surface move.

Bonus:

Connect it to a canister filter packed with mechanical filtration media to purify the water showtime before information technology sends the catamenia downward the UG filter tubes from the outlet.

Hullo, sparkling clean h2o!

goldfish gravel substrate — Image credit: Pixy

Advantages of Undergravel Filters

Quiet

Annoyed past loud sputtering, gurgling, trickling or dripping from other kinds of filters?

The just noise just most will be coming from your air pump vibrating (if you use ane).

If you work in an office or want a quiet tank in your room this tin be a large perk.

Invisible

But about every filter out in that location is an ugly intrusion into your cute aquarium scene.

There'due south almost no way to totally hide most of them.

With Undergravel filters, you integrate the filtration so closely into the aquatic surroundings there is almost no transition.

Huge biological footprint

You can't vanquish the surface area the size of your aquarium's footprint.

Terminate of story.

Substrate Aeration

Prevents bad anaerobic forming in the substrate when set upwardly using the methods described above – score!

It's okay to go heavier on your layers of substrate since yous are getting oxygenation happening.

Conclusion

I hope this post sparked your interest in the possibilities of filtration with undergravel filters.

What about you?

Take you tried them, and what take been the results in your tank?

Featured Image Credit: PDPics, Pixabay