This is a very difficult thing to do. The main reason is there is no restrictions on the pool service industry. Anyone can call themselves a pool guy.
1. Make sure the Pool Guy is Licensed (CPO or La County Certified): This means he had to at least pass a test in the pool service industry. The scary thing is all you need is a business license and you can go to any pool supply house to open an account and buy anything you want. One example of this is: If you mix Chlorine & Muriatic Acid together (every pool guy has a lot of these 2 chemicals on their truck) you get mustard gas. If you are not educated you don’t know what to do when these chemicals mix in the event of a spill. I have seen entire city blocks shut down because a pool guy’s truck flipped over and he had no idea what to do to stop the gas.
2. Make Sure the Pool Service Carries Insurance: Now days pool guys are getting sued left and right. There are so many reasons it is important. If he were to fall in your back yard and get hurt. If he spilled chlorine or acid on the deck of the pool. Sometimes it is not the pool guys fault but sometime it is.
3. Hire Someone Who Looks the Part,Makes You Feel Comfortable, and is Knowledgeable in the Field:
Looks the part: If you are interviewing someone in a suit and tie to clean your pool something is wrong. They should be dressed like a pool guy.
Makes you feel comfortable: They should be able to communicate effectively to you when they come by to look at the pool. You shouldn’t have to worry about them in your back yard. If anyone is honest you will get good and bad news when they go into your backyard. I have never walked into a perfect pool in someone’s backyard.
Knowledgeable in the Field: Technology finally hit the pool industry 10 years ago. Within the last 5 years it has exploded. Every pool show we go to some one has some sort of new technology they say is the next best thing. Bottom line is this. With technology comes convenience and usually more cost. However some technology like Variable Speed Pumps will save you a ton of money over time. A good Pool Service Company will educate you. When they come to your house they will give you options, tell you the pros and cons of each and let you make the decision. There is no 100% right answer for every customer. Every customer is different and every pool is different.