Interesting possibility. Water quality does vary considerably across US, but even in close proximity - depending on depth of the well, cities right next to each other can be pulling water from different aquifers.
In general the NPK numbers are the important and the brand does not matter. The are proponents of non-urea Nitrogen fertilizers as urea is slower to break down and release Nitrogen.
The Michigan State University studies are the best and they believe than Phosphorus does little for plants.
A study at the University of Florida found phosphorus applied to orchids absorbs 60% of the phosphorus applied in the first 20 minutes. It can easily overdose an Orchid.
Phosphorus can take up to 5 years to break down.
It is now illegal in Florida and commercial growers have gone to 17-3-17.
High phosphorus does not cause extra blooming while in fact it kills beneficial microbes in the medium and makes the plant almost impossible to absorb magnesium and other trace elements.
You can get the same results as 'bloom boost' fertilizers by stopping all fertilizers or using very low nitrogen fertilizers.
Considering using Potassium nitrate (spreadable variety - water soluble - not granular) during the winter. It is probably about 7-0-45 or something close. This will aid root growth when the orchids are not producing leaves and flowers in the cooler temperatures.