Hi once again on my quest to the holy grail of understanding all things planted (in water).
I sat and pondered the light issue, you may know by now I have softish water, which I am in the process of buffering.
At first I noticed a heavy drop in pH and allthough this did go up (very much) the first night it went even lower the next day.
So i started penciling a kind of graph (i know these processes arent quite as linear) which roughly indicates the relationship between the hours of lighting and pH level.
How was I contributing to the increased swings daily?
well, by extending lighing hours, I will attach my little graph at the end...
Extra light will increase the period during which the pH will rise forming more basic (alcaline)conditions, I suppose its slightly cumulative to the point/threshold where buffers will restrain it. I.e. on day 2 the pH could go even higher...
The shorter light day had a smaller rise in pH and during the longer dark period the pH had longer time to drop, and over time would appear to apeal to water going more acidic (until buffer kicks in)??
Even day night alows for equal times for pH increase and decrease = more stable conditions which with the addition of buffer would create smaller swings. I do still think there might be a slight(or nasty) swing if CO2 levels varied alot/stopped for some reason.
Now I doubt that the rate at which the pH climbs and falls in light and dark are equal (like in my picture), but please bear with my train of thought and over simplification unless you can point out specific faults or ways to correct them.
This might at best be confirmation of previously established advice.
At worst you can correct some missconceptions about the processes and scales involved in the light cycle.
Cape Town, South Africa
25 Gal. 54watt, DIY CO2 5 Angelfish, 1 male dwarf gourami + 2 females ,2 female betas, 3 albino corys, 2 pepper corys, 2 CAEs
15 gal. Dwarf gourami fry tank
10 Gal 3 variatus platies, 4 black sailfin mollies- 5 Gal guppy birth tank with dividers
5 Gal guppy frytank
1 Gal guppy frytank
40 Gal Pond with 10 female guppies, 1 male tons of fry.
On various pieces of furniture, 6 cats!