I just replaced my ???old,???k 175Mh with a new 10,000k blueline.WOW does that look better. I never thought the old one was that bad.I now also take back every bad thing I ever said about the blueline bulbs. I got two of them,as the price was right.And now will be getting another retro for the other bulb.Can't wait to see the improvement that two of these babies makes in my tank....HOW OLD ARE YOUR BULBS?????