If you regularly brushed the pool and ran the pump/filtration and added DE to the filter after every backwash, the pool should have become more clear and less cloudy. If not, then you've most likely got a problem with your filter. You should check that fist to make sure the sand isn't clumped or that the filter is getting bypassed anywhere (multi-way valve in wrong position or leaking).
With your low CYA level (20 ppm) and higher FC level (10 ppm) that oxidizes the Metal Magic product so re-releases metal back into the water. Since you clearly don't have algae at this FC/CYA level, you shouldn't have that ratio be so high. You should probably get your CYA up to at least 30 ppm so that the chlorine isn't burned off from sunlight and you can lower your FC down more. If you lose too much during the day from sunlight, then bump your CYA up to 40 or 50 ppm. Make sure the FC doesn't drop below 7.5% of the CYA level, but don't have it be as high as you have now.
Once you get your FC/CYA ratio lower, you should find that the Metal Magic holds better and only needs maintenance doses once a week. As for the CuLator, call the company and tell them you are using their product and are not seeing improvement -- they can have you check the bag to make sure it is working and may have other advice which you can share with us.
Once you've verified that your filter and its sand are OK, then we can try other clearing methods, but really if the DE in the sand filter isn't clearing the pool, then I think you've got a filtration problem and whatever non-standard techniques we have you do won't necessarily make things better (i.e. use of GLB Clear Blue or BioGuard Polysheen Blue clarifier or use of OMNI Liquid Floc Plus or BioGuard PowerFloc flocculant).