I found this and another.
It is thought that an ingredient in Kent Tech M will kill Bryopsis; and that we can indirectly monitor the application of this ingredient by monitoring the magnesium levels in our tanks. People use Tech M to raise the magnesium level in their tanks by no more than 100ppm each day (to help prevent issues to our livestock, due to a sudden change in parameters), until magnesium levels reach 1800 to 1900ppm. These levels are then maintained for up to 4 weeks and then left to decline via consumption and normal water changes. It has been recommended that use of a Poly-Filter be discontinued during this time as the effective ingredient could be adsorbed by the media.
Both were basically the same with the second one saying to maintain the 1800 for only two weeks.
Hope this helps.