Debs - I'm not carl either, but just to let you know, those of us who do use DE as a supplement in the sand filter do so by adding 1-2 cups of it through the skimmer - your pressure should change by about 1.5-2 lbs - this shows you have loaded it with enough DE.
I would do this when you are ready to start cleaning up all the dead algae - you will get your pool clean much quicker.
Pre DE, It took me about 3-4 good vacs to recover from a bloom, now, 2 will do it, and the second is more a final spot clean than anything else. However, my backwashing increments increased proportionally!
You will find that you will only be able to vac about 1/3 to half your pool before you have to backwash - this is a good thing, it shows and proves that adding DE works well.