I think you have enough light for most plants, just not enough for a low growing lawn of HC, for example, or for some few very high light demanding plants. Most plants should do fine with that light. Your stem plants should not be planted in a big bunch - no more than 3 in a single bunch. And, that glass top is going to irritate you to death eventually, getting covered with white water deposits, dust, getting in the way of feeding and pruning, etc. For the little good it does I don't think it is worth it.