Numbers are meaningless. Different strains can take different intensity. You just have to figure out what your genetics like. Generally around 1100 - 1200 umol-s1 is max and should only be used through mid flower, backing off the intensity during ripening to decrease foxtailing and increase density. Less light and cooler temps during ripening with a ripening feed that has high K and low N.
Foxtailing can be caused by too much heat, too much light, too much nitrogen in late flower and sometimes it's just genetic. If you only see it on the tops closest to the light then eliminate nitrogen as the cause.
