Category Archives: Water physics

Neptune module taken into action

Finally. After a long time building the hardware and the software, the Neptune module is the final module to be added to the Paludarium.

This module is a more complex version of the Apollo units that live inside the Canopy that control lighting and fans. The Neptune module has some control for lighting (namely the underwater lights), but its main purpose is controlling pumps and valves, and measuring back sensors in the paludarium.

For now the Neptune module is setup in the cabinet under the Paludarium:

The Neptune module sitting in the cabinet under the Paludarium with some sensors already connected. What a mess of wires and hoses!

The Neptune module sitting in the cabinet under the Paludarium with some sensors already connected. What a mess of wires and hoses!

The unit has been running for over two weeks now without a single flaw… I must be doing something right ;)

The stuff Paludariums are made of

People are often confused what things are all in the paludarium, what they are called and what they do. In this blog post I’ll explain the different components (sub projects if you will) that make up the paludarium today.

A quick overview

In order to get the paludarium working as it works today, I had to run several different projects and put them all together. First I’ll quickly list all the different components:

  1. The Cabinet – The custom-built cabinets that hold the paludarium;
  2. The Paludarium – The glass structure that holds water and air (the paludarium is a closed construction);
  3. The Land part – The part above water. Filled with tropical plants, and for now no animals here;
  4. The Aquatic part – The front underwater part of the paludarium, where the fish live;
  5. The Sump – The rear underwater part. Any excess water from the Aquatic part is dumped here, and the plants living on the background panel get their water from here (and return it there too);
  6. The Waterworks – The board in the cabinet that holds all the plumbing (water valves etc);
  7. The Canopy – The intelligent armature sitting on top of the paludarium;
  8. PaluPi – A standard Raspberry Pi with an RS232 level converter that sits inside the Canopy and handles all the “smart thinking”;
  9. Apollo units – Named after the god of light, there are around 12 of these units inside the Canopy, each handling up to 4 leds, halogens, TLs or fans;
  10. Neptune module – Still under development, this unit controls all pumps, valves etc in the Waterworks;

Quite a list right? Everything in this list had to be tuned Read more »

Bringing all technology together

As the paludarium slowly got all parts in place, I set myself a goal: I wanted to have it filled with water on my birthday! That proved to be a LOT of work; but it paid off! In this blog post I’ll show you the final tidbits that made the paludarium ready to contain water.

background and waterfall

The background now has two layers of epoxy where I poured this jungle soil over the epoxy. The result is almost covering the background, and not that much white is showing (from the styrofoam). Now it was time to glue the background in! I used aquarium silicon glue for this:

The background being glued in place. Note the stick under the background to make sure it stays in place.

The background being glued in place. Note the stick under the background to make sure it stays in place.

Note the stick that holds the background in place while the glue dries. With that done, it was on to Read more »

Rain Down On Me

One of the last things to build and test with all the water stuff, was rain. So I added a small installation with sprinklers that get fed directly from the tap water.

Rain Down On Me

The rain installation is controlled electronically (duh!). On the WaterWorks under the paludarium, I have one electromagnetic valve that can be opened to feed the rain installation:

The magnetic valves on the WaterWorks. The one on the left controls the osmosis filter, the center one inputs tap water into the aquatic part, and the rightmost has now been connected with a thin black tube to allow for rainfall.

The magnetic valves on the WaterWorks. The one on the left controls the osmosis filter, the center one inputs tap water into the aquatic part, and the rightmost has now been connected with a thin black tube to allow for rainfall.

The valve on the right has now been connected as well with a thin black tube. This tube is fed upwards, and Read more »

The Paludarium Completely Filled

Today I filled the paludarium fully. Now the water levels are exactly as projected, and overflow neatly into the sewer if there is any surplus.

Filled up

Fully filled, the paludarium weighs around 370 kilos right now. And I still need the Canopy on there, sand inside… But the cabinet is holding up perfectly. Nothing bending through, nothing giving way.

If the tap water or the reverse osmosis unit is turned on, it fills the aquatic part. The aquatic part overflows in the dirty-water part in the rear. If that overflows, it is dumped straight into the sewer:

Detail of the sewer pipe in the paludarium. Any access water will flow straight into the sewer. Note how the water is exactly leveled to the edge of the drain.

Detail of the sewer pipe in the paludarium. Any access water will flow straight into the sewer. Note how the water is exactly leveled to the edge of the drain.

The inside of the paludarium is a bit of a construction site right now. It looks like this:

Water in the paludarium fully filled. The aquatic part left is about to overflow to the dirty-water part (right) and in turn that water is drained to the sewer.

Water in the paludarium fully filled. The aquatic part left is about to overflow to the dirty-water part (right) and in turn that water is drained to the sewer.



Hoses ‘n stuff

There are a lot of hoses inside the paludarium Read more »

Water for the First Time!

Today it was finally time… All the puzzle pieces for the WaterWorks could be put together! After testing the WaterWorks for leaks, it was time to mount the board under the paludarium, hook things up and test… For the very first time actual water inside the paludarium!

Mounting the WaterWorks

The waterworks were build on a separate board, outside of the paludariums cabinet. All parts that need to be under the paludarium that handle water are mounted here. The WaterWorks look like this:

The Paludarium WaterWorks. This board is mounted under the paludarium and it handles the water household.

The Paludarium WaterWorks. This board is mounted under the paludarium and it handles the water household.

Today I mounted this board in the cabinet under the Read more »

The Way Water Warms


I am so happy with my Raspberry Pi now able to obtain real-time measurements from the La Selva biological station. As much as this station measures, it does not measure water temperature. Time for some geeking out!



What I DO have

So the measurements I do get from the biological station are basically all the ingredients I need to synthesize the water temperature. Especially these values will determine the temperature:

  • Light Intensity;
  • Air Temperature;
  • Rainfall;
  • Previous Water Temperature.

I want to use some kind of calculation to create a synthetic water temperature. I’m assuming sunlight will heat the water. The water temperature will somewhat follow the air temperature. Finally rain will seriously cool down water.


Making up a formula to synthesize water temperature

Forming a formula that synthesizes water temperature is kind of hard to do. There are so many variables. In the wild, water will come flowing in from somewhere else. Deep water will flow slowly, and hardly heat up under sunlight. A small pool of 10cm of water will heat up extensively, unless it streams fast.

It is almost impossible to work with all these variables. So I figured to just build a simulation formula, and see how the water temperature will develop as I run through the days. I started out with a formula like this:


WaterTemp = WaterTemp + (Light/settings.get(“synth.lightFactor”))
WaterTemp = WaterTemp + (AirTemp-WaterTemp) / settings.get(“synth.AirTempFactor”)
RainDiff = Rain * ( WaterTemp – settings.get(“synth.rainTemp”) )
if (RainDiff < 0): RainDiff = 0
WaterTemp = WaterTemp - ( RainDiff / settings.get("synth.rainFactor") )


The first line will increase the water temperature from the last sample with (Light/factor). This is the heating of the water by the influence of sunlight.

The second line first calculates the difference between air and water temperature. The further apart, the bigger the effect will be. After dividing by a factor, I add this difference to the water temperature (this cal either heat or cool down the water)

The third line first calculates the difference in temperature between the water and the rain. Then I multiply this number by the number of millimeters of rain (more rain = more cooling). In case the rain is warmer than the water (should never occur), I do nothing.

Finally I subtract the calculated value from the water temperature divided by another factor. I use these factors to tweak and tune the simulation.


The result

I still have to look at the effect in a longer run, maybe import a few weeks of simulated data into excel and graph it out. So far it seems to behave pretty well… Simulated temperatures normally run from 24 degrees centigrade (early morning) up to 27.5 degrees centigrade in the late afternoon (4PM). Rain cools it down 1-2 degrees. When looking at heavy rainfall (like September 11th 2013 where there was over 70mm of rainfall in 1,5 hours), the simulation delivered a water temperature of 21.4 degrees centigrade. Not bad at all!

Paludarium Waterworks

I finally have all the stuff I need for the construction of all of the plumbing around the paludarium. So next was to decide where to place what. And that proves to be quite hard; I have less space than I initially anticipated…

How to place plumbing inside a cabinet

The first question was: How do I place all of the required plumbing in a cabinet while I’ll still be able to work on it properly without having to hang inside the cabinet all the time? The answer was to build everything onto a piece of multiplex and then placing the entire multiplex board inside the cabinet (and then connect up all of the hoses).

I ended up with something like this:

The wooden board where most of the plumbing will go.

The wooden board where most of the plumbing will go.

At the top left tap water will be connected via the hose laying on top. This hose will connect Read more »

Hardware ‘n stuff ordered!

Today I finally ordered most of the hardware I’ll require for the further construction of the paludarium. Not computer chips this time, but pumps, filters, pipes, heaters and other cool stuff. In this blog post I’ll highlight some of the components that I’ve selected.

Aquatic Filter

Originally I used an Eheim 2222 external filter for Paludarium 1.0. However, this filter was already too small, so for the new Paludarium 2.0 it would definitely be too small, so I was in need of an upgrade. The price of the larger Eheim filters scared me a bit – So I decided to go for another vendor, JBL. They have a much cheaper filter line, the greenline filters:

The JBL Greenline 1501e external filter

The JBL Greenline 1501e external filter

I bought their 1501e version, which outputs an impressive 1400 litres per hour and Read more »

Paludarium Feed-throughs mounted

After the cracked glass of the paludarium was fixed, I could continue to mount the feed-throughs. This is a vital part to build before any water can be put into the paludarium, as right now there are some huge holes drilled in the glass bottom :O

Different types of Feed-through

There are several types of feed-throughs planned for the paludarium:

  1. Feed-throughs feeding through the back that will run into the waterfall (3x);
  2. Feed-through feeding through the back for cabling;
  3. Feed-through in the bottom where the filter will draw dirty water from;
  4. Feed-through in the bottom where waist water will stream from into the sewer.

All the feed-throughs have rubber rings in order to make them watertight. I applied some vaseline to the rubber rings which will help to make them waterproof. Read more »