was getting ready to fill my 4000 gal new pool when i notice about 1/2 to 1inch of rain water on the bottom that was a light brown color, was wondering if i need to get rid of before filling pool up, thaks.

Contact Gator pool directly, they would be more than happy to assist you. Personally, I would clean any debris out of it and fill it up. 4000 gallon of water and chemicals once it's filled, would clear the water. I have a 24 foot round pool, and that's what I would do. Hope this helps. Safe swimming. 🌞

I would suggest putting in about a quart of bleach and stir it around with a brush. Then fill it up. Once full and running shock with Burnout. We will be glad to test a sample of the pool for you as well.