This product WILL RAISE YOUR pH. From a chemistry perspective, there is no way this supplement cannot raise pH.
From the Brightwell page:
The hydroxides are the problem. Hydroxides contribute to alkalinity when they combine with atmospheric CO2 dissolved in the tank.
This is how limewater/kalkwasser increases alkalinity.
Hydroxide combines with atmospheric CO2 to become bicarbonate:
OH- + CO2 => HCO3-
Hydroxide also combines with bicarbonate to become carbonate and water:
OH- + HCO3- => CO3-- + H2O
Carbonate and bicarbonate are the majority of total alkalinity in reef tanks. This product must raise alkalinity. There's no way that it cannot.
As of the time of this post, there are no liquid additives that can increase pH without increasing alkalinity. It used to be only Seachem outright lied about boosting pH without raising alkalinity. Looks like Brightwell has joined their unsavory company. What a disappointment.