Glad you have already found a CO2 value that works for you. Don't know what drop tester your using but if I am not mistaken most have the green as indication of an ideal level of CO2.
I see no reason why to turn it on during ambient light periods. You fauna and flora have been breathing CO2 out all night long so there is already some in the water. Not much if you have a good water agitation but still some.
If you want you can try Seachem excel. Its liquid carbon source which can supplement your CO2 injections so you have a bit more CO2 in your tank during ambient light (don't use the full amount suggested for your tank size- you will want to supplement not increase). It is also claimed that it helps with algae too, but I don't know how your critters will react...Do a little research on the matter just to be on the safe side.
It takes patience and a lot of asking and reading to grow them tall and thick.
I think you are off to a good start..
You are at a good place. There are a lot of knowledgeable ppl on this forum you can really help you as long as you ask and you show interest.