Does anyone know the reason why LUX loses value when changing the PHI2 algorithm?
No good news recently, that's one of the reason. The coin itself is in good shape, but while some good news have continuous positive effect on coin development, the market price reacts instantly on it, and all of the continous effect is kinda already included in pump. This usually not a big deal since continous effect on development might lead to even better new good news, and bigger rize of price.
Another possible reason is quite good POS reward, which historically a bad factor for the price.
Anyway, it's not really possible to say why exactly. Best traders in the world can't give the advice even on short-term investments, because they unable to predict it (unlike newbies, they understood it in long practice), they just trade in the moment. Therefore, what hope is there for us to predict or analyze it...