Oppossite light cycle

[Subsea]

I have posted a similar thread in advanced topics but thought it was relevant to this macro forum, so here it is.

When first operating a refugium 40 years ago, the school of thought was to use Caulerpa on a 24 hour light cycle to prevent it from going sexual. Then the standard became the oppossite light cycle to stabalize pH during lights out. There is no oppossite light cycle on the reefs of the world. Why is pH steady stae of such importance. My sumpless tanks have no oppossite light cycle. The pH fluctuates between 8.1 and 7.8 with no ill effects on tank community. In fact at 7.8 aroggonite will begin to dissolve helping with buffering and trace mineral addition.

Last week, I changed refugium lighting schedule to run simultaneous with DT. Display tank is 75G with a 4" DSB Jaubert Plenum with a mud and macro refugium. This tank has been set up for 10 years.

We shall see what moderate pH fluctuations do in a mixed garden reef tank.

[Michael Hoaster]

It's not required, but (in theory) a good practice to help with stability. It also stabilizes oxygen levels, which could benefit fish and sensitive inverts. Plants consume, rather than produce oxygen at night, so oxygen levels are lowest in the morning. Having a 'fuge producing oxygen at night smooths out this variation.

[Subsea]

It's not required, but (in theory) a good practice to help with stability. It also stabilizes oxygen levels, which could benefit fish and sensitive inverts. Plants consume, rather than produce oxygen at night, so oxygen levels are lowest in the morning. Having a 'fuge producing oxygen at night smooths out this variation.

Oxygen is the most important thing. Yes, it is true that photosynthesis consumes carbon dioxide and produces oxygen. However, that is not the only process that adds oxygen and removes carbon dioxcide from the water. Gas exchange at the water air interface needs to be maximized particularly if there is no surface skimmer as would be in a sumpless system. With a refugium, the surface skimmer aleviates surface tension of the air/water interface in the display tank by removing scum, therby promoting better gas exchange. In my refugium, the first chamber is bioballs which further enhance gas exchange.

[Moort82]

If stability is an aim then by switching the photoperiod to an opposite cycle is the easiest thing you can do. Some people also pay less for electricity at night so it's win win. Does it majorly affect the tank, probably not but even if it's only helps a tiny amount it doesn't take much effort, so why not.

[Subsea]

If stability is an aim then by switching the photoperiod to an opposite cycle is the easiest thing you can do. Some people also pay less for electricity at night so it's win win. Does it majorly affect the tank, probably not but even if it's only helps a tiny amount it doesn't take much effort, so why not.


It is a "Question of Balance". "Steady State" pH is not the goal. The ocean reefs pH fluctuate between .1 and .5, if it works like that in nature, why should I change it in my marinre tank.