I have 5 Indicas and 1 Sativa in my system and each day between their 16th and 17th hour of light (Ihave them on 18/6) all the Indicas start to sag, the leaves look perfect, there's no wilting, they simply go limp. The next morning they are all standing proud. Is this normal? The Sativa never changes, it's always perky. The plants are all growing like crazy and look flawless otherwise. Do I need to be concerned? Thanks!