Water in the trap
Before laying their eggs, mosquitoes taste water and control its pH.
When plants, such as dead leaves deteriorate in the water, they regularly release organic acids that reduce pH water thus make it acid. This acidity means that there are plants and thus that grubs can eat. The water in the trap should remain clear as “a brewing tea”.
Acid water reduces diseases contracted by fishes such as white spots (Ichthyophthirius) and other soft water parasites.
4 to 7 days after the installation of the device, and once the trap has been filled with water from tap and that there is a heap of dead leaves with a size corresponding to an A4 sheet, then the trap is thus more attractive to gravid females.
It is better to wait the first grubs to appear before introducing fishes because this allows checking that the trap is efficient.
If water turns to green, this means that the trap is too much exposed to light; and thus has to be emptied and moved to another place.