Thomas G. Marshall . com wrote:

and therefore concluded it was a good idea to try
filling PVC tubes and using those as posts
(note-not as sonno-tubes, but as fully structural
support posts).

Ignorance is bliss.

I used PVC for my mail box post. Went down 18 inches, carved
out a 3" foot lip, crisscrossed 8" bolt at 6" and 10", filled
with concrete and rebar. My mail box was getting knocked
down by cars sliding on ice.

Someone was knocking down mail boxes with a baseball bat.
The police found him when I told them to check for people
with forearms. This clown broke his forearm and his wrist.

But as a deck support, that's a joke.

Dick