If you feel like taking a risk, leave it in. If you feel like playing it safe and keeping your fish alive, take it out.
By the way, there is no benefit to leaving it in anyway, considering plants use CO2 in unison with light to create glucose sugars. That is how they create food to survive. Without light, CO2 cannot be used, so it is completely pointless and there is no benefit!
To sum it up, take it out!!