I wouldn't get too excited about Brighty K. There's no magic involved as it's basically
Potassium Carbonate (K2CO3) + water. Does this sound like something that can neutralize chloramine? The correct answer is "No". If you add enough of it there might be an increase in alkalinity but that's about it. There can be no comparison between TPN+ and Brighty K. TPN+ contains N, P as well as K and micronutrients, although TPN+ might actually be a bit low in K. Adding either Brighty K or K2CO3 certainly won't hurt, but there is no way they can be used in lieu of TPN+.
If you are not suffering Potassium deficiency then there is no reason to add more Potassium. If you want to add more K to see if it makes a difference then it would be a lot cheaper to experiment using either of the widely available K2CO3 or K2SO4 powders.
Cheers,