Tenax and Mark,

Not to beat a dead horse, but I have seen that same flow limitation published on an otherwise authoritative website. (I think it was about choosing the correct pump size)

It doesn't make sense (if you think about it carefully) but they give no explanation for that gpm limitation and, as nearly as I remember, refer to it as an absolute.

You simply have to be skeptical of virtually everything you read especially when written as an absolute, irreffutable fact.