Here we go with some facts about the balcony pond:
Below you'll see the best picture I've taken of it so far. I think I'll be able to post better images in the near future. For now, this is the best I have.
How big is the aquarium?
The aquarium you see in the picture has the following measures:
- Width: 80 cm.
- Height: 40 cm.
- Depth: 35 cm.
If we ignore the fact that two edges are cut, this gives us a volume of 80x40x35=112000 cm^3 or 112 liters.
How much water is in there?
Right now, as I write this, the water covers 32 cm of the aquarium. This is more or less 80% of its capacity. Taking into account these two cut edges on both sides, I'd say we have some 80 liters of water in it. At the beginning of my experiment, I put 60 liters of tap water. It has rained a lot since then and now I'm not surprised to have gained 20 liters of water in the aquarium.
Where is it?
The aquarium is placed in a balcony which is looking west. The balcony belongs to an apartment in the third floor of a wonderful building in Berlin. It is not covered, so when it rains water pours into it freely. There is no much sun protection either (besides the fact of being in Germany). It is close to a wall, though, so when it is sunny it only gets direct sunlight half of the day. The weather has been horrible since the beginning of spring so I haven't worried much about over-exposing the aquarium to sun radiation.
What is in it?
I'll put a list of seen things from my very-unprofessional-unscientific observations. This is what I have so far:
- Snails. I think they are "great pond snails". There are five adults. A couple of weeks after setting up the aquarium, I discovered some eggs attached to grass floating in the surface. Last week the eggs disappeared and I expect to see tiny snails all over the place.
- Thin plants that grow vertically and very fast. Some have reached many cm above the water surface.
- Plants that grow radially. They are possibly algae. They expand from a center point with radial branches which in turn become centers for further expanding.
- White "tentacles" coming from the ground that move as if they were fingers trying to reach something. They are everywhere and they look creepy.
- One big worm. That could be a leech. It shows up only from time to time (no idea where it hides) but when it does it is scary. It's 6-7 cm long and moves around quite fast. What is it eating? There is no blood to suck in there.
- A white spider (well, it looks like a white spider to me). At the beginning I thought it was dead because it didn't move at all. Then I saw it in different places. One time it was chewing.
- Millions of small larvae swimming around from the bottom to the surface. They are all over the place. They all seem to be from the same type and they only differ in its size. I hope they are not mosquitoes. I also hope to have some predator ready to eat these insects in the aquarium (the white spider maybe?) or I think I will face a plague.
How is the water doing?
I have measured the water four times. All values haven't changed much during time. The pH stays between 7.5 and 8. The KH Carbonate hardness is between 7 and 8 dKH. The level of Nitrite has been always below 0.01 mg/l and the level of Nitrate below 0.5 mg/l.
One value that has changed is the concentration of iron. At a measurement on April 22, the level was above 1.5 mg/l. On April 29 it was 0.8 mg/l and on May 23 it reached 0.6 mg/l.
That's it for the post today.
Carlos.
