Those who are familiar with my tank know that I've had a minor bryopsis problem for a few years. By decreasing the phosphate level in the system I've been able to get most of it under control. However a few areas still remained. Most notably along the spraybar that extends across the lower back of the tank. Some of it can been seen just to the right in the picture of the the platygyra if you scroll up the page.
On RC I had read about some impurity in Kent Tech M that for whatever reason kills bryopsis. So after watching a friend experiment with it on his own system I gave it a shot too. I purchased a 64oz bottle and added 200ml daily for about two weeks until I ran out. This brought the Mg in the system up from 1300ppm to 1500ppm (the total system volume is just over 200gal). Some of the bryopsis I pulled out manually which I would do monthly anyways and the rest yellowed and disapeared.
Here is a picture of the spray bar now bryopsis free:
