So what should I do next to it?

I went by one pool place today but They only had the large 25lb bags of the DE powder and I didnt want to buy such a large amount since you said I only needed a few pounds. I went to tractor supply store next and they had a small 4lb bag of DE powerder used to treat bed bugs and other pest. Here is the brand they had. Would this be OK to use to test my filter? If not I guess I'll just buy the 25lb bag.

http://www.tractorsupply.com/safer-r...asedPricingCmd