Ik heb het 'grote boek' er nog eens bij gepakt
'Ecology of the planted aquarium' van Diana Walstad. Zij zegt het volgende over verlichting, ik citeer:
"Providing adequate lightning for the planted aquarium can easily degenerate into a confusing muddle of technical terms about light intensity and wavelengths. Beginning hobbyists should realize that many lightning systems will work. (…) One must not forget that aquarium plants are basically shade plants; they need much less light than many terrestrial plants, floating plants, emergent plants, and marine corals. For example, one submerged plant (Myriophyllum brasiliense) can only use about 10% of the light intensity of it's emergent form. Excess light only stimulates algae."
Dan iets verder in het boek gaat ze in op de hoeveelheid licht per dag, ik citeer:
"Short daylength (less than 12 hr) may signal plants, hormonally speaking, to stop growing. Many plants perceive short daylength as a prelude to winter and/or dry season. Their growth rate slows or may stop altogether. (…) A midafternoon siësta mimics the natural condition-a temporary overhead clouding during a summer afternoon.
Moreover, a siësta allows CO2 regeneration. With continuous light, plant photosynthesis depletes most of the CO2 by late morning. This means that during the afternoon, plants are competing for an ever dwindling supply of CO2. Algae, which is more adept than plants in taking up CO2, gains the afternoon advantage over plants. With the Siësta Regimen, though, CO2 is regenerated when the lights are off.
Ook gaat ze in op het fluorescerend effect dat onze verlichting heeft op de planten, ze haalt een onderzoek aan met verrassende conclusie, ik citeer weer:
"The fact that plants did very well with Cool-white, which produces mostly geen-yellow light was unexpected. One would have expected plants to do better with Vita-Lite, because Vita-Lite was designed for growing plants. Its spectrum, which is rich in red and blue light, better matches the light absorption of plant chlorophyll than Cool-white. Cool-white was found to give off 13% more photosynthetic light than Vita-Lite. Perhaps Cool-white's slightly higher light intensity explains its better performance? However I would also argue that green-yellow light is what many submerged aquatic plants encounter in their natural environment. Aquatic light is not like terrestrial light where the blue and red wavelengths predominate. Aquatic light is unique. This is because the water itself (H2O) absorbs red light, while DOC absorbs blue light. What is leftover for plant photosynthesis is mainly green-yellow light. Aquatic plants may have adapted their photosynthetic machinery (over the course of evolution) to use green-yellow light fairly efficiently.
Op basis hiervan heb ik het licht schema aangepast naar:
06:00 tot 07:00 zonsopkomst
07:00 tot 10:30 zonlicht met nadruk op groen licht.
10:30 tot 14:00 siesta
14:00 tot 18:00 zonlicht met nadruk op groen licht.
18:00 tot 19:30 schemering
19:30 tot 21:30 avondverlichting
Effectief komt dit neer op zo'n 9 á 11 uren licht, afhankelijk van of je de avondverlichting mee telt. Eventueel zou ik de schemering nog wat kunnen oprekken.
Verder heb ik ervoor gekozen om nog 1 plant toe te voegen, de Hygrophila polysperma. En nog 1 plant te vervangen, de Nymphoides hydrophylla gaat plaats maken voor de Nymphaea Stellata. Dit was de enige plant die niet helemaal biotoop getrouw was, en daarnaast vind ik de rode bladeren van de Stellata een welkome afwisseling. Ik verwacht de planten a.s. dinsdag. Dan zal ik ook direct het water testen.
