It certainly does help, but compared to the amount of light in the DT during the day, it is not the same. But IMO, the sway that you're seeing isn't that big and shouldn't be much of an issue. I don't know if you dose at all, but if you do, wether manually of with a dosing pump, you can try and dose your Alk in the evening hours, which will also help to lessen the ph drop during the night hours.