1. EG (有毒) v.s. PG (無毒)
2. 不是很靈敏就用 Bromocresol green (Spectrum catalog BR 135) pH 3.8 (yellow, lots CO2) ~ pH 5.4 (blue, trace CO2)
3. 非常靈敏就用 Bromocresol purple (Spectrum catalog BR 138) pH 5.2 (yellow, lots CO2) ~ pH 6.8 (purple, trace CO2)

多玩多看吧 !