per i curiosi del fotoperiodo, ho trovato quanto segue dal sito della dennerle che conferma anch'esso l'interruzione a mezza giornata (midday break)
Reduce the lighting duration from 12 hours to 10, 9 or 8 hours, for example. Or even better: Grant your plants and fish a &

20;midday break&

21;.
The following rhythm has proven effective: At least 4 - 5 hours of light in the morning. Then a break of 2 - 4 hours without light. Followed by at least 4 to 7 hours of light. The tank should not be totally blacked out during the break (diffuse light from a window 2 - 3 metres away or an incandescent lamp positioned 1 - 2 metres away).
The periods with bright light should always be of at least 4 hours' duration. Plants will be unable to make effective use of shorter periods. Contrary to common belief, we have not observed any negative effects on either fish or plants. Presumably because strong reductions in light are relatively common in the tropics, as a result of thunderstorms, for example.
Algae evidently do not like these &

20;midday breaks&

21;. It remains to be established whether this is due to the fact that the &

20;primitive&

21; algae are less adaptable than the &

20;modern&

21; aquarium plants or whether an improvement in the oxidation/reduction balance is the primary factor here. This method proves amazingly effective at combating algae.
(During the first days of this change in the lighting rhythm, you should measure the O2 and CO2 content regularly and adjust the CO2 supply accordingly. Less CO2 is usually required).
Spero sia utile.
ciao,
Nico