Where to buy DE?

We frequently advise to add a small amount of DE, 1/2 c or 1/3 c, to a sand filter to boost filtration of fine particles. Where do people get these small quantities of DE?

What I've found at various pool stores in my area as well as the big box stores is 25# minimum for a cost of around $25. That's a chunk of money for something of which I really only need 6 oz or so.

Are there other uses for DE besides as filtration medium? What do you do with this stuff once the water is fixed?

Must it bee swimming pool DE or can you use food grade DE to add to the sand filter? I know the food grade is suitable for a variety of household uses. Is the pool grade DE treated in some way to make it different from food grade?

Clearly, I know next to nothing about DE :)

Pool filter DE is different than food grade or gardening DE.

DE for pools comes in as small as a 10 lb box for around $10 (CURRENT PRICE BTW). I know becaue I used to sell it. Most people don't buy the small ones so many stores do not stock them.

If you have an ace hardware near you check them out if they sell pool chemicals and carry HTH, many bigger Ace do. They should have it in smaller boxes.

You can also order it online from several retailers including Ace. Just google HTH diamtomaceous earth.

As far as how much to add, it is generally between 1/2 to 2 cups (enough to raise the pressure by 1 psi and not more). You just don't want to add more than 1/3-1/2 cup at a time in a slurry through the skimmer when you are trying to see how much YOUR filter needs for the 1 psi pressure rise since it is easy to overshoot.

Since it does not go bad and you will need to add it with each backwash one box will last you that long time so even if you need to buy the bigger box it will get used up in time.

Thanks a ton for the ACE info, I'll check with them.

This pool DE, can it be used to deter crawling insects? I have to be very careful with DE because of the dogs, don't want them inhaling it. I've used a DE containing product in the past to scatter along the house foundation and basement windows and it's worked well.