Ducting and Vent for external DC

[poolhound]

If by "fine collection bag" you mean the original plastic type, there shouldn't be a penalty for reducing its size, since it doesn't allow air to exhaust through it. And your airflow may be best with all bags removed, but I didn't see if/where you are ducting to the outside, so wasn't sure if you'd abandoned that approach. Does that enclosure have any exhaust? If not, you might be creating back-pressure that could also diminish your airflow, and possibly trapping fines in suspension. I'm not an expert, but I don't think I'd be comfortable with the chance of trapping any fines in there with the electric motor.

As I dont yet know how much difference it would make I didnt want to go and cut any holes in the nice new siding :-) Once I have a chance to test later in the year and if it seems worth the effort I will make some type of flange that attaches in place of the bag with turnbuckles and will connect to some 6" hose/pipe I will exhaust through a vent in the side.

[Stytooner]

Looking good.
Here are a couple poor pictures of how I did my manometer and pitot tube.
It worked great.

[poolhound]

Looking good.
Here are a couple poor pictures of how I did my manometer and pitot tube.
It worked great.

interesting I take it the pilot tube is open, did you rig some form of small tube or needle on the inside?

[Stytooner]

I don't recall all the details about it. It was 14 years ago.
IIRC it was a small brass gas fitting with about an eight inch hole or orifice. It was just threaded flush into the side of the short pipe and sealed. Add some food color to your water. I had some guidance to build it from somewhere on the internet back then, but do not recall where.
Here is a Youtube video where a guy builds a pretty simple one. He doesn't go into the math of it, but it is used in his shop for testing his filter efficiency.

I found these two images from around the time I was doing this to mine. I haven't looked closely at them, but they may tell you something?

[capncarl]

Poolhound, pm sent.
capncarl

[poolhound]

Dang Lee, that's some hairy math right there! I think I will just be going for the relative measure i.e. get a baseline and see what makes for more or less for more or less suck.