if you buy wood from petco
Just wanna say thank you for those who gave me suggest on yellow water issue last week.
I went to Petco buy another small piece of wood and put it into a bowl with clear water. The water turned to yellow after one day.
If you buy wood from Petco, make sure you do some preparation before put it into your tank. Otherwise, like me got yellow water.
ALSO, I found them buried ferns under substrate :C