Με τις λάμπες υδραργύρου έχω φτιάξει ενυδρεια ζούγκλες πριν απο 20 χρόνια, ειναι ένας απο τους 3 τύπους λάμπας προτεινόμενης στο Optimum aquarium της Dupla
And I quote:
Mercury vapor lamps are usually hung free over the aquarium. Earlier they were mainly used in industry, and were only discovered for aquaristic use by Aquarists upon the publication of a book entitled »The Perfect Aquariumu, eight years ago. Today there are countless mercury vapor lamps giving between 50 and 250 watts. However, a number of these lamps are not suitable for our use, because their radiation angle is so wide that the light which we want to have in the aquarium goes beyond the measurements of the aquarium. For this reason we should like to present the functions which the mercury vapor lamp must fulfill at any rate.
1. The mercury vapor lamp must have a deep parabolic reflector which gathers the light with the least possible loss, and directs into the aquarium.
2. The mercury vapor lamp should not blind the Aquarist in any way, when he is sitting in an arm chair in front of his aquarium.
3. The housing of the mercury vapor lamp must be rust free (aluminium) so that even the smalles amount of water from the aquarium cannot rust the underside of the lamp.
4. The mercury vapor lamp must be switchable, for example from 80 to 125 watts in order to be able to use less lighting at a later point, after initial good plant growth. In this case, of course, the original 125 watt bulb must be exchanged for an 80 watt bulb.
5. Last but not least, we should like to mention that the mercury vapor lamp should blend in form and color, with the Aquarists' house, and should be in harmony with its environment. The fifty watt mercury vapor lamp has not had much success in the hobby, because it is not economical, and does not bring the desired results.
You wont regret using them.