You could do the math up front and then dose at full strength. Saves you the hassle of finding mixing containers and the mixing. BTW, the ratio appears to be 1.5% (Excel) versus 2.6% (Metricide). (The ratio issue has been explored here
.) I've seen folks either dose Metricide at 50% or 60% of the Excel dose and not report issues. I just started dosing to fight some BBA and am using 50% of what I would have used with Excel.