Working with pvc

[JimE]

dont go up 2 sizes or more as the weight of all the extrra water in your vertical pipe runs will increase head loss dramatical

So completely wrong I don't know where to start, sigh. It will do no such thing, other than to REDUCE friction loss and perhaps increase flow in a particular application.

if using hard pvc pipe using long sweeping elbows helps dramatically to improve flow

"Dramatically" is quite an overstatement IMO - slightly is a better term. If you understand friction loss and friction loss tables, they show that elbows typically aren't a huge "detriment" to a typical system. If long sweep elbows were so wonderous as everyone makes them out to be, they would be a standard plumbing item - which they are not.

Jim