Yes. Nighttime. That is why I said CAM plants specifically. I don’t know!The air to the skimmer is taken from the outside but there is huge interface in the water surface that´s bring down carbon dioxid that not are consumed during night by my refugium (Light on during night) - The refugium is a little bit to small - it does something normally (the pH curve is around 0.1 higher when the refugium lights are on. In February - I run my refugium lamp between 21:00 - 9:00 - you can see the pH dip in the chart
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Today - I switch of 10:00 and at that time the photosynthesis in the DT have start to "absorb" CO2 - no dip around 9_00 now - the small dip you see some days is earlier and probably caused of the fact that two persons have left their bed
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Now to the plant issue. I do not think is a very good idea because I need the CO2 during day time. My corals are using more than the amount going down from the air during day time - During some time I switch air to the skimmer between day and night - maybe I should do it again. Its the air´s content during nighttime that´s problematic. The best way to handle this is probably to do a larger refugium - but there is no way I can do that
We have green plants - but also a cat that love to walk om the shelfs to the widows
Sincerely Lasse