Re: If you buy diatomaceous earth- food grade, where?
What are you planning to use it for? Unless you are going to sprinkle it on your floors and furniture...? That would work/be necessary if you had an infestation, but for a deterrent, that's just going to make a mess! Are you planning to feed it to your dog? Feeding DE only works to eliminate parasites from the intestines.
I know fleas vary from one place to another, but I haven't found them to be a big deal. IF I see one on one of my dogs, I treat the dogs with Frontline or Advantage. I've only had to do it twice (in the past 5 years or so). You are supposed to treat them like every three months, but I don't like the idea of pesticides coursing through their veins. After treating them, I saw no more fleas (for a few years). Never saw any in the house or bites on anyone people in the family.