Very glad to read that things are looking up.
My plants really hated 6 hour days. The Persicaria Kawagoeanum only carried ~6 leaves per stem, leaves were only a couple inches long and the lower leaves and stems had BBA on them. On 8 hour days the leaves are at least double the size, stems carry more than a dozen leaves and I am not seeing BBA on the old leaves. Sure hope that keeps up. I am sure the algae would love 8 hour days more if I didn't shade the tank. It makes a big difference. Put some window screen or cheesecloth over the tank and set the light for 8 hours. In a couple weeks take the shade off for an hour a day. If that goes well, 2 hours and so on. Since the plant mass is larger and plants themselves stronger they can handle the added light. I am up to 4 on/4 off as of last week.
But keep it at 6 hours for right now as it is working for you, just something to consider trying later on.