Ok, I've found this interesting...
Many people believe it is "general knowledge" that Salifert is 2 dKH higher than Elos. Most people believe Elos over Salifert.
In the mid 2000's in the USA it was popular to keep alkalinity at 9 dKH. The most popular alkalinity test kit? Salifert.
In the last few years it has become more and more popular to keep alkalinity 7 dKH. Interestingly enough Salifert is losing sales as Elos creeps into the market.
NSW alkalinity values are usually around 7.0 dKH (
Randy Holmes-Farley).
Is this all coincidence or just works from my particular perspective? Opinions are always relative.
I'm not the first to notice this interesting trend though.