In contrast to the ATI Blue Plus, which creates an intensive blue light ( max. by 450 nm) , the ATI Actinic produces a violet-blue light (max. by 421 nm ) which is less brighter, but which emphasizes the flourescent pigments in the corals. We are enforcing our bulb terms and warranty effective March 16, 2021, no exceptions. T5 bulb warranty: You will get 100% refunded should the manufacture declare a bulb defective or should a bulb arrive damaged. Our warranty does not cover shipping or re-shipping fees for T5 bulbs. ATI T5 Bulbs have a 30 day failure to fire guarantee. You MUST test your bulbs within 30 days