strike water volume changes

I have been reading Brewing Better Beer by Gordon Strong and he suggests to calculate mash thickness, or water to grain ratio, based on the water in direct contact with the grain. If using a false bottom strike water volume is increased by the amount of water under the false bottom not in contact with the grain.

This makes sense but I have a HERMs system so I am constantly recirculating the mash water. I am not sure whether to follow his advice using my system.

Does anyone calculate strike water using Strong's advice?

Strong's advice regarding increasing the water volume is good, even if you do use a HERMs. Go with it.