I have spent some time researching the archives on UGH's. Everyone seems to agree that both versions (low wattage .1-.2 watts/l and high wattage .5 watts/l ) are very benefical to plant growth. However, the issue of long term stability with the low wattage approach remains in question. As many of the comments on this topic are somewhat dated (1994-1995) I'm curious about the current thinking on this topic. Ross