pH fluctuation in morning and night

[akahoshi]

Why does the water's pH level drop at night and morning? Is it because of a rise in carbon dioxide?

[mansiz]

Is your lightings off during morning and night? Ph do drop a little when lights are off, thats why many people drip kalkwasser during this period which can main Ph and maintain calcium as well. Or probably get a 24 hr refugium, probably it helps.