Just a little background for perspective. A lot of our dust is smaller than 1 micron. In fact some of it makes it through a 1 micron Slime Bag. There are few pools, out this way, that use anything other than DE filters because of our "microscopic", "cementous" powder-dust. When I use cellulose for the pool I do get the best filtration and virtually as good using Aqua Pearl (similar to DE but without the silica). I have to keep the filter running round the clock on low speed/flow, though, to keep the pool as clear as it can possibly get. (It will never be as clear as pools in areas that have less extreme conditions but it is pretty darn clear.) The only time you can see a hint of haze, in the pool water, is at night in front of the light and it is very slight.
With that being said....... I use the standard pleated spa filters (not disposable) and my stand alone spa never has any floaties in it unless we use scrubby gloves to exfoliate (and change the filter out for a clean one the next day) (I have four and change them out after cleaning, and an occasional soak in bleach/water, at least twice a week.) The tiny exfoliation floaties are gone in a few hours with filtration. OR if something is out of balance (hasn't happened since last year when I discovered TFP) or I've gone too long between filter change outs. But then, they really aren't "floaties" rather the water is a little cloudy. It sparkles up within a few hours of filter change out.
This summer, several times, I have left the cover off for as long as a week at a time and haven't gotten floaties other than leaves or bugs. The same powder dust that blows into the pool blows into the spa too.
The spa filter keeps the spa water even clearer than the pool water with big Quad DE filter, running round the clock.
My pool stays clearer if the flow of water through filter is on the low end. Starting, clean pressure at 3.5 psi or so at ~ 20 gpm. That is a really low flow rate. In fact I turned it down to 15 gpm a little while ago as the filter needs a backwash which it will get in the next hour or so. When it goes from 3.5 psi to 20 psi the Intelliflo pump shuts off unless I lower the flow rate.
Likewise my spa circulation pump is very low speed/flow and runs 24/7 for very little electric cost. The jets are pushed by two separate, big 5 HP pumps but the water does not go through the filter from the jet pumps.
I had floaties when a bio-slime (bacterial) took up residence in the spa pipes. It took a major decontamination to get rid of those buggers.
If I saw floaties in my spa now that I know how to manage the water properly, thanks to TFP, and keep filtration going all the time, and change out the filter often enough, it would be an indication that something is not right.
I've used BBB for a year now, sometimes bromine and sometimes chlorine. I'm doing bromine now but next refill I'm switching back to bleach as I think it is easier to manage; my personal preference.
Keeping water balanced, keeping sanitizer above minimum at all times, running enough circulation/filtration, and keeping filters pretty clean has been the cure for any problems I've had in 24 years of spa ownership.
I tried the disposable, expensive "micron" filter a few months ago. This did not work out for our situation as you don't take these out to clean them. It filtered very fine particles (although the regular filter cartridge does too) but the fine stuff built up too fast and coated the outside with little going into the inner fibers. Our dust acted sort of like DE does in a DE filter and caught everything at the outside layer; too expensive at $30+ for only one month of use and filtering no better than the pleated cartridge, reusable filter.
Someone on the board, who has an Intex pool, purchased a bag that goes over the throw away cartridge that some Intex filters use. Actually you are supposed to use the whole system which consist of a frame and washable bag, matched to your filter size/type. I looked up the seller on eBay and I'm going to get a message off the the seller to see if he has one to match my spa filter. If so I'm going to try it out as it takes a lot of water and time to keep my spa filters clean and is a royal pain in the winter, doing it so often. With that system you only wash the bag. I don't know if it filters any finer than the pleated cartridges but it might. I'm interested not to get better filtration but for ease of use, especially in winter when we use the spa the most. I'll look up the link.