I don’t suggest using anymore floc.
You must open the filter to check the sand, deep clean it, or replace it. After the floc is removed this is the last step.
Here’s the guide for that
This post will walk you through the anatomy of a sand filter, and then provide a video at the end for how to deep clean your sand filter. The filter used in the photos and videos is a Hayward S180T top mount sand filter. The images are of a similar filter. Obviously not all filters are...
www.google.com
That little cordless vacuum you have will not capture the fine particles and instead just blow most of them out.
The robot might do better than the handheld if you use the pleated fine filter instead of the mesh filter. It will fill up quickly and unfortunately also stir alot of it up. So it will take many runs & need breaks so things can settle back down.
Otherwise the best option is vac to waste manually very slowly with a basic hose & vac head.
Once you feel you have removed the majority of the floc and return to filtering you may try adding a little pool grade DE to the sand filter to help catch the finer particles (no opening the filter needed)
Here’s the guide for that
A clean pool filter will increase the efficiency of your pool! ... your filter are to backwash it, clean the manifolds and grids, and add new DE.
www.google.com
You’ll need to be sure you’re around to check the psi as it can rise quickly and need to be backwashed. The de is removed with each backwash so you can decide when you do & don’t want to use it.
During all this be sure you’re keeping your fc up so you end up with more issues
See —>
FC/CYA Levels