Its just a hair high. I would try to keep it at 420. When you do water changes you put nutrients back in the water so in all reality you probably don't.need to dose anything.
I just read a post here is what that person said. You should not add anything to the water you cannot test yourself.
Good point IMO
. I wouldn't rely on lfs
testing. I know it costs money to buy liquid tests but they will pay off in the long run cause all out takes is one bad reading by lfs
and your replacing all your live stock ya know