Building a styrofoam waterfall

One of the main features in any of my paludariums is a significant water body. As I then have both land and water, a waterfall should definitely be part of the setup! I have always created my waterfalls out of styrofoam. In this post I will share more details (and do’s and don’ts)

Sourcing styrofoam

This turned out to be one of the hardest things: Where to get a styrofoam block thicker than 8cm without the need to buy a truckload of it? This turned out to be harder than I thought. For previous builds I have always been lucky to find pieces of styrofoam casted away at build sites. The best one was a road being reconstructed near my home that ran through the marshlands. They constructed this road… Floating on styrofoam. You can imagine the size of those blocks! Even the smallest piece of discarded styrofoam would not fit in the trunk of my car 😛

For the previous build I wasn’t that lucky. In the end I settled for layers of thinner (5cm) styrofoam plates glued together; a “don’t” as I was soon to find out.

Take care of leaks

As I glued layers together and cutted out the waterfall stream through those layers I discovered that any leaks will cause water to flow between the layers and leak on the sides; a REALLY annoying dripping sound as a result. In this setup there were no separate “land” and “aquatic” households, so the leaking wasn’t really a problem.

In my new setup I DO have two separate water households: The filtered aquatic water is pumped up through a hole in the land section, then gets dispersed into the waterfall. The waterfall will carry the aquatic water over the land section into the aquatic part. As you may understand it is vitally important that this setup won’t leak; if there was aquatic water leaking into the land water household, it would at some point be discarded into the sewer, so I would effectively pump the aquatic water out of the setup over time. Not good.

Single sheet waterfall

In the end I went for the thickest sheet of styrofoam I could get my hands on, 8cm thick. This would be just enough to have a small section where the water is pumped into, then overflow into the actual stream. I should just work! First I layed out the shape I would need on a piece of paper:

Up next, I started cutting the 8cm thick styrofoam into shape. I used an electrified resistance wire. I have one of 1M length, and a plyable 20cm length one. After cutting of a gazillion little pieces (the wife will love this!) I finally got it fairly good in shape. This is way harder than it seems! You need to cut in an angle downwards, stay level and make sure the water won’t flow over the edges:

Some do’s and don’ts:

• Make sure the edges are high enough. My filter puts out 1250L/hr so it needs some height;
• Always make sure the stream goes down all the time;
• Make sure the waterfall bed is always level, otherwise the water will flow on one side only;
• Create the waterfall out of a single layer of styrofoam if possible;
• Seal the waterfall properly (this proved harder than it looks).

Sealing, coloring and adding sand

In order to seal the waterfall I ordered two-component epoxy. I got a food-safe variant, because 1) it is food safe, but 2) the viscosity was one of the highest (which helps closing holes and shaping). I put on two layers both top and bottom. I used coloring agents (grey and brown) to color the sides. Don’t overdo the details, as stuff grows over it will hide most anyway. Next I put in a separate layer of epoxy on the bedding, and pressed sand into that layer while it was unset.

Time for the first test! I put the waterfall into the paludarium, and then poored water onto it. The water streamed nicely, but I immediately noticed drops underneath; the sealed waterfall wasn’t as sealed as I had hoped.

After drying I investigated. As it turns out, the styrofoam I used was very open, and even after applying two layers of epoxy I could actually SEE holes sitting in the bottom. It took several more layers of epoxy to get this fixed, and finally I also put a thin layer of silicone on the bottom to stop any final mini leaks.

I know a lot of people use things like Drylok to close and shape their rocks and falls. I did not want to venture there, as the Drylok might give of calcium which would cause the water to become less acidic; something I do not want as I am building out an Amazon-like setup where there is no calcium in the water. It is basically black water (also known as “tea” 😉 ).

Two separate water households

It took some thinking to get to the system where I have two separate water households. You might wonder WHY I want that. As I have discovered in previous setups, the land portion will leak an amazing amount of nutrients into the water. Great for aquatic plant growth you’d think, but in reality it did not work out that way; plants would hardly grow and fish would mysteriously die while others seemed healthy and unaffected. I have heard the story told more than once: “In a paludarium aquatic plants do not grow“. I believe this is one of the reasons people say that.

After deciding I needed separate households, it was off to design something that keeps them apart, while still being easy to construct (and something that will actually KEEP working). I ended up with the idea that I needed a separate “sump” where water flowing out of the land portion could gather. Excess aquatic water should overflow into this sump. When watering the backdrop I would use water from this sump, and the water should (largely) flow back into this sump, not touching the aquatic part.

I have seen people build a separate rear section (I have actually had a setup that featured that as well), but it takes up (too much) space. So I designed a smaller one:

The land section sits on top of the sump. Aquatic water will definitely “escape” though the cracks between the sump glass and the land section that comes on top. In the image above you can clearly see two feed-throughs through the bottom of the setup. The one in front is the overflow; any water above this level will drop into the pipe (which leads to the sewer). The other pipe is longer and runs the water into the waterfall that comes on top of all of this.

The final construction is shown a better in the image below:

In the image above you can clearly see several things. First of all the white egg crate creates the false bottom. The land section itself is water sealed as well, and constructed out of HPL sheet (a type of plastic). So any water that comes through the land section will fill up the space the eggcrate creates. It finally flows out of the hole where the white round 3D printed filter basket sits. The hole sits exactly over the sump area underneath, so that any land section water will flow into the sump. A 20mm pipe runs through the center of this filter basket, through the waterfall into the waterfall. Makes sense?