Hello everyone....I have a gunite pool and first time closing it. I have already blow out all the lines and the main drain but not sure if I should leave the main drain valve open for the winter season. I have the pool installed last year and the pool company did the pool closing for free (part of the new pool package). And I think, but not sure, the pool guy leave the main drain valve open after blowing all the lines. Now I am not sure if I should leave it open or have it closed after reading some forum and internet search and didn't find any info about gunite pool, kind of worry if I do it wrong. I have already added the anti-freeze on the return lines and the skimmer, also not sure if that's enough. Tried to call the company and of course they won't let you talk to a service tech without scheduling service, so no help. Please any feedback will be greatly appreciated and thanks any help in advance.