I have powered a few tanks with Stingrays very successfully--a couple 20 highs and a 55 long. Currently all 3 of those fixtures are on my 55 now to get better spread and punch down to the bottom better. With those plants a Stingray would be just fine but if you're going to use one make sure you give your plants all the help you can by placing them off the substrate on driftwood or rocks and using a full 2 or 3 inches of substrate. The Dwarf Sag though I don't have much experience with and I can't say I'm certain it would thrive under a Stingray. If you plant some tall, low tech stem plants in the back though they're really great at reaching for the light so a Stingray is great for appropriate stems. Wisteria, Water Sprite, low light Hygros, and Rotala are what I'm currently using under my Stingrays but the Rotala grows very thin stems. Still looks good though.