You are really focused on that 29 days. I am looking at it like this...your milk has a BEST BY date...the milk does not go bad at midnight, you got a day or 2 of wiggle room.Fair enough. I am always the skeptic, lol.
Obviously different tanks have different algae growth patterns. My tank with zero nutrients will be very different algae growth from someone’s softie tank.
Their current claims regarding the subscription make ZERO sense to me.
If they did not force that it needed to be changed every month, I would be much more interested.
For their claim to be accurate, it has to fall within 2 areas.... either the results after 29 days are still perfect, or they are no good. And that’s based on algae growth..... which is a factor that varies a LOT.