All my Selaginella got contamination after sterilization phase. I already

try to change method for sterile it such :-

1. soak them in fungicide + tween 20 

2. rinse with dh2O (3times)

3. dip in 70% ethanol (30second)

4. soak in sodium hypochlorite/clorox (20%-60% concentration) / 0.1% mercury chloride(HgCl2) for 5-10 min.

5. rinse with dH2O (3-5 times)

6. dry it on filter paper

7. put in media

Any suggestion, what should i do to improve it from contamination?

Thank you.