As a former floc user I can confirm what has been said. The critical things:
Never vacuum to a sand filter. The cautions in the article are true, including the part about it later breaking down, and clouding the water again.
You don't mention the filter you have. If you have a way to direct the water to waste, bypassing the filter completely, use it. If you can vacuum on high speed, and move VERY slowly, you can get it off the bottom and out. You will use a LOT of water, and have to stop and refill to keep going. If you put a hose in, point it at a clean area, to avoid stirring it up. When done, leave the system off, and let it settle - overnight, or better another 24 hrs. More will settle out, and you'll have to vacuum again. It may even take a third session.
If your filter is DE don't use it until the pool is cleaned up. Then clean it, after all the vacuuming to waste is done.
If a cartridge, you may not have a way to vac to waste. Then your only option is to vacuum at a moderate speed, so as not to break it up too much. But some will break down and go back into the pool. So it may be more repeats of vacuuming, letting it settle, and then doing it again. Clean your cartridges while waiting for it to settle out. Pay attention to the jets - you may see bubbles or even dirty water coming out. That's your sign to stop vacuuming and clean the filter.