Need help with small shop DC upgrade
So I have a very small shop in my basement. I haven't measured it recently, but I feel confident stating its dimensions at no more than 12x12. Probably more like 10x10 or 10x12, but you get the idea...very small.
Here is what I currently have in place:
I have the Harbor Freight 2 hp dust collector. It is mounted on the little rolling platform that it came with, and I'm using the filter bag and collection bag that came with it also. I have a DIY cyclone-style pre-separator that I made myself from a plastic trash can. The DC system is connected via a combination of 4" PVC Sewer & Drain-grade pipe and 4" flex hose (flex used only for the last few feet to each tool) to the following tools:
-1 drop to my table saw (Grizzly G0771Z 10", 2HP 120V)
- 1 drop to my Bandsaw (Grizzly G0555XH 14" 1 3/4 HP)
-1 drop that is alternated between my router table, miter saw, and belt/drum sander
The DC setup captures a fair bit of dust, but a lot of it seems to be getting belched right back into the shop. There is perpetually a thin layer of dust on everything. I'm guessing the HF filter bag is a big culprit there, along with less-than-perfect seals on the fittings between ducts and pre-separator.
Here are some of the things I'm considering:
-replacing the filter bag with a canister-style filter
-replacing the 10" impeller on the HF DC with the 12" impeller from Rikon
-replacing the PVC Sewer and drain ducts with 4" metal ducts with foil tape at the joints
-running the ducts at floor level along the walls so as not to make the DC have to fight gravity
-replacing the plastic trash can homemade separator with a better DIY unit made from a 55 gal. drum and a shop-made Thein-style baffle.
-adding a ceiling-mounted dust filter
I was initially looking at upgrading to 6" ducts, but from what I've read online, the HF 2hp doesn't have enough power to justify that.
Here are my questions:
-are any/all of the above worth doing? That is, am I likely to see improvement from said upgrades?
-assuming the answer is "yes" to the question above, from which upgrades would I see the biggest improvements?
-if the answer to the above is "no", what would you recommend doing instead?
Thank you for considering these questions and for any guidance anyone can provide. I really appreciate it!