What can be done about a very loud I mean very loud pool pump or some other device directly behind our house that runs during daytime and nite hours.we can't hear each other outside on patio.other than this it is a relatively quiet neighbourhood.

Call president of the HOA or call Leland Management and ask about what can be done. They should notify the owner and have them change it. If you are a resident there, maybe go and see if the owner lives there and discuss with them.

Do you own the house or do you like rent the place from a vacation company? If so please contact the owner of the company.