Separating the aquatic system from the land system

When I built Paludarium 1.0, I was positive on having solved the water poisoning by not using potting soil anywhere in the landmass. As it turns out, the plants on land rot away leaves and build their own soil inside. Very nice for the plants, not so nice for the fish inside. since the water streams through the soil, it picks up a lot of chemicals that aren’t very healthy for the fish in the aquatic part.

For the reason staed above I decided to build Paludarium 2.0 with two completely separated water households: One aquatic and one for the landmass. When I started to think up Paludarium 1.0 way back in 2005, I did not want to add this very complexity (I was thinking about a brackish aquatic part at the time). As it turns out, even without a brackish aquatic part, I still need separated water households. In this blogpost I’ll sketch the first global design on these separated water households.

Basic requirements

The basic requirements for the separated water households are pretty basic, and these determine the design that I’ll make:

  1. Separate water households for the aquatic and the landmass part (obviously);
  2. Being able to add fresh tap water through reverse osmosis into the aquatic part, and spill any surplus to the landmass household;
  3. Spill any surplus water inside the landmass household directly into the sewer;
  4. Have a small pump for circulating (NOT fitering) the landmass water;
  5. Have a large external filter being able to filter the aquatic water household and stream out into a waterfall;
  6. The external tubing from and to the aquatic part should be injected just above the aquatic waterline, not though the ceiling of the paludarium (which is the case with the current setup).

Looking at all these requirements, I thought up a system similar to the one depicted below:

Figure 1: Separated water segments in Paludarium 2.0 (sideview; front is on the right)

As you can see, some holes need to be drilled in the paludarium glass walls and bottom to get this working. The way it works: There are two wet zones: the Aquatic Zone and the Manure Zone, separated by a glass divider. Both store their respective water households.

Through the blue pipe the water is extracted from the aquatic zone of the paludarium. The water runs through the external filter, and is returned to the aquatic household through the red pipe. The reverse osmosis device delivers clean water which can be injected to the aquatic household through the purple pipe.

Any surplus water will spill over this separation wall into the manure water household. The green circulation pump inside this segment will pump up the water all the way to the top of the paludarium, and drizzle it down again along the back, straight back into the landmass water household.

Finally, any surplus water in the manure water zone is drained using the grey sewer pipe. This pipe is connected directly with the sewer system.

Heating the system

Heating is something to be considered. By inserting a heater into the red pipe, the aquatic zone can be heated to the right temperature (22-28 degrees centigrade). Since this zone is the biggest mass in the paludarium, it will effectively heat the air inside the paludarium to almost the same temperature. Secondly, the manure zone will also heat up to acceptable temperatures for plants living above the surface. I am not counting in rain (which comes from a separate tank kept at 18-20 degrees centigrade).

The reverse osmosis device will convert (the somewhat substandard) tap water into very clean cold water (10-15 degrees centigrade) into the aquatic zone and this might influence the temperature of this zone, possibly harming the fish. Also, the water coming from the reverse osmosis device is so pure, that it is actually poisonous to fish. However, the output of this device is rather small. These small amounts of fresh water will mix very gently with the water inside the aquatic zone, so the heater in that same segment should have no trouble heating this to an acceptable level. Also, this slow and gentle mixing should allow me to use this pure water because it will mix with the available water in the aquatic segment. If not, I’d need to inject chemicals to mix down the “overly clean” water into a “healthy” state for the fish inside. Should not pose any real problem.

Controlling it all

So now that the basic design is a fact, how do we go about automating this? I can start out simple: Both pumps need to run 24/7 anyway (bacteria inside the filter would die if it stopped and the plants above the surface would die if they did not get water from the circulation pump).

Heating can also be done very simple: The external heating could be set to any “fish friendly” temperature and the entire eco system inside would follow.

Finally, controlling the reverse osmosis device can be done by hand. When you would normally perform regular water changes in an aquarium, you’d now just open the valve for a few hours and the water would be changed automatically (and any surplus water would simply be ditched into the sewer). A big plus of this approach: the waterlevel is ALWAYS constant if I leave the tap open a tiny little bit (in a paludarium you can have massive evaporation).

It would be a nice feature though if I could utilize a channel from the current controllers to control an electric valve which automatically changes the water every x days for a duration of y hours 😛

Automation in the next level: Sending measured data back to the automation unit?

In Paludarium 1.0, I never got round to automate up to a level where the controllers inside the paludarium (which are over 12!) can send measured data back to the paludarium. So there just was controlling, no data was sent back at all. If I could add this feature (the electronics SHOULD have support in their hardware but this was never tested) I’d be able to measure temperature of land and water, and control the heater accordingly. I could even vary it for night and day as I do have this data available (see the realtime status page). Also, I might be able to measure the conductivity of the water in the aquatic segment to determine how “dirty” it is and control the automatic water changing from there… Definitely something I will be trying to include when I work on the electronics in the future!

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