Surface debris

Welcome to TFP. Here is the hard part: Photos so we know what you see, test results from one of our recommended test kits, tell us how you treat your pool, put the particulars of your pool and equipment into your signature. That is all information needed to help evaluate this. The easy part is fixing the issue and then maintaining the pool properly. Read the following links.
Pool Care Basics
Test Kits Compared
FC/CYA Levels
PoolMath