looking to get ro unit for my tank i am going to have auto fill .do i hook it to cold or hot water and when i do water change can i just add salt to the sump and let the fresh water fill up the sump?
Cold, and NO. You need to mix salt well until it completely disolves prior to putting it in the tank. Unless of course you plan to shut down your return pump until the salt has disolved.
By the way your going to be very happy with ATO. I know it is one of the best things I did for my reef.
looking to get ro unit for my tank i am going to have auto fill .do i hook it to cold or hot water and when i do water change can i just add salt to the sump and let the fresh water fill up the sump?