Presumably, that's a very big pool: how big?

Meanwhile, you'll need to get a 25# bag of DE powder:
Diatomaceous Earth (DE) Pool Filter Powder 25 LBS. @ Amazon.
You may be able to get it for less, locally at Home Depot, Lowes or a pool store. You'll need it BOTH to test your filter, and to help cleaning up the water.

And, you'll also need a K2006 test kit - links below in my signature.

Re-reading this, I'm guessing you have a commercial pool? If so, you need to get the K2006C (2 oz size) PLUS (2) K1000 kits. Also, you need to tell me what your daily bather load is, and whether the pool is outdoors or inside.