The actual visibilities depend on the ability of the divers. This means that especially on weekends visibility can get worse. On top of that, sunlight immediately gives 1-2m more visibility at a depth of 7m.
Please find the actual visibilities at: Sichtweiten
Each of the four large drum filters cleans 150 m³ per hour
Visibility depends on the lake's levels of nutrients. We have to feed the thousands of fish that live in the lake - this means we are adding nutrients. On top of this we get influx of dust and so on.
Service divers regularly remove the forming sediment, and the installed filtration systems clean more than 9,000m³ of water every day.
Even so, variations in visibility cannot be avoided. Depending on temperature this happens over periods of 1-2 weeks, but can also flutuate by several metres during one day.
The ability of divers is an important factor.
100 good scuba divers will hardly affect visibility, wheras a just a few who can't control their buoyancy swirl up a lot of sediment.
Beginners are only allowed into the lake in company of experienced divers - but evern highly qualified scuba divers scuttle through the lake as if weighed down by 50kg of lead...
Visibility in the caves
is usually 20-60% better than in open water, mainly due to:
Less light = less algae
The dim light in the caves supresses algae growth
Because the caves are mostly closed from above, they get much less silt.
What we do to improve visibility:
An elaborate vacuuming system is installed in the lake.
Also, service divers suction sediment from the corners. A strong influx of pollen has caused a 20cm layer of sediment to form in a few days.
Without the constant work of the service divers and without the elaborate filtration system visibility would be less than one metre in the summer.
Evaluation of Visibility
"Bad visibility!" curses the under water photographer, "one metre at most". He shows his pictures: The sturgeon swims toward him and is about 1m away. The fish's 1.5m length is visible and then some. That makes at least 3 metres. This isn't an isolated case.
Underwater visibility is perceived 50-70% less than it actually is. An object that is 4m away in the water is perceived to be only 3m distant because of how light behaves there.
There are also other factors: in misty conditions or in cloudy water our eyes automatically focus to 1-2m and report this distance. Driving through mist is exhausting because we have to constantly fight against this automatism.
There are also other, very simple reasons: People who dive with their masks steamed up and complain about bad visibility. Many do without optical glass in their masks and see less because of that.
The international standard method is to use a white disk at the end of a pole that is held into the water. At increasing depth the contours become blurry.
In the scuba diving park there are also a few good objects for orientation:
Distance between the cat statues
- 3m in the row
- 5m to the opposite row
Distance between pillars: 3m
Wheelhouse to prow: 10m