If the water is cloudy or stinky it needs changed period. Otherwise I would start out changing once a week if I were you, and then trying to see if you can go 10 days or more. I personally would never go longer than two weeks.
How do you tell if it needs to be changed?????this is going to be a DWC system
you should change the water week depending on the size of ure res. There is no way you are gonna tell wen to change the water by lookin at it or smelling it
Weekly is fine for 4 gallons, but as I said, if it is ever stinky or cloudy, change it regardless of how old it is. I never said to leave the water in until it's stinky.There is no way you are gonna tell wen to change the water by lookin at it or smelling it
Light proofing will help reduce algae but it does not address the many other reason that the water needs changed. Changing once per grow is fine if it works for you, but giving someone the idea that all they need to do is light proof and they will be OK is doing them a disservice.If your container is light proof, you wont have any problems.