Update... Cautiously optimistic a day after a couple changes. The affected canoe leaves have almost completely flattened back out. Since I made several changes I can't be sure which hade the greatest effect. Using de-chlolrinated water in the mister didn't hurt although I've not seen anything on the subject. Raising the light a little more meh...maybe. I also increased the exhaust rate. My hunch is that this was probably the most helpful. Perhaps starving for CO2 or asphyxia from elevated O2? Shame on me for not increasing air flow sooner as they got bigger. Cranked light to 60% and will continue to monitor and increase light intensity incrementally. We shall see but I think it's headed in the right direction. Thanks for the kind responses.