Initial setup thoughts/tweaks and advice

[inigomontoya]

I was downsizing my 75g freshwater and decided I wanted to still keep a tank. The best deal I found on craigslist was actually "setup" for saltwater and, despite my dad having enjoyed but agonized over one for many years before giving up, I decided to try the switch.
The setup I bought is a 40 gal cube with black stand, a bak pak2 (which is a skimmer and biobale biological filter)and originally a coralife pc w/ 50/50. I have already upgraded to a Current Sundial T5 setup. The original owner said it worked fine with just the above for years. Other additions have included a Koralia 4 and a Koralia 750gph.
I started with live sand and live rock (roughly 35-40lbs by now) and have finished cycling. My goal is to have a mixed reef, primarily softies and LPS.

I also have limited space (and didn't leave enough room for the bakpak when setting up so don't want too much more HOB items). I was able to get some chaeto from a local reefer and have placed it in the bakpak section with the biobale. I removed about half the biobale and am considering removing the rest.
My questions were in the area of mechanical filtration- I put a tetra hob filter on briefly to get cycled and it is now in the newly setup 10gal QT tank in another room. I was thinking about removing the biobale entirely and just letting the chaeto take up that space but currently that catches the "stuff", detritus and the like, and is the only filter I have. The chaeto might also serve to catch the fine grains of sand, etcetera but don't know how much it would like being rinsed in sw during water changes to get "stuff off- which is what I am doing with the bale.
I also initially put on some floss- the polyester batting- to get some fine grained sand dust out of the system and am considering using that in conjunction with the chaeto and/or biobale (just tossing when done). CPR has a pre-skimmer but not a fan of that design.

Lastly, I bought a thin strainer that fit on the pipe to keep the chaeto from entering the tank but also have overflow concerns. I don't want the chaeto to get caught up in the flow pipe and empty my new tank. Thanks for the thoughts-sorry for long post-enjoying the hobby and found the site to have lots of information.
Any thoughts on inexpensive tweaks to the above are appreciated. Just don't have money/space to set up a sump or anything similar.

[dots]

Personally.....tanks that size, I think the filter is just for getting the chunks out of the water.....and would rely on WC's to keep the Nitrates down.

BTW, Welcome to RC.