My pool installation has been completed, we had some warm days here in OH. The pool was filled with water to under the skimmer and returns. My question comes in regarding blowing the lines. I’ve read a ton of posts, watched a million youtube videos and I’m more confused. The returns are already capped off and never had water in them, the skimmer lines as well don’t have water. The main drain obviously does. The installer think the lines don’t need blown, he used flexible pvc(I know I know) my question is what is the best way to at least do the main drain this year? If I use a compressor at the pump I’m concerned on using too high of pressure or not enough. A picture of my setup is below it does return, skimmer and main drain, the salt cell is inside , any help or advice would be great!