Looking for a reason why my Walstad tank is having this problem. The tank consistently tests 0 across the board but this stuff is still growing. I’m going by Diana Walstads suggestion of a 5-4-5 siesta lighting schedule. The tank does receive some daylight for a couple early morning hours during the time the artificial light is on. I’ve been doing 10% water changes daily with RO water to reduce the amounts minerals in the water from the tap water but still no dent in it.