A combined bulb should last with it's UV output for at least 12 months. After that, slowly the UV will begin to decrease. Look to replace after about 15months. Hope that helps. You also get a 12 month warranty with the Arcadia combined bulbs, so if it blows/malfunctions - you can get it replaced, no quibbles. Just keep a proof of purchase or something. Tweet tweet, Birdy !! xx
