Changing water... usual recommendation is switch water 1/4 weekly. But for new tank it could need more frequent change in particular before water is clear.
about 液肥, there is no fixed rule. your observation to plant condition is the key. And we start at extreme low amount and increase slowly- usually no 液肥 in first few week after new tank setup.
Recommend you to read these introductory papers - very useful.
http://www.aqugrass.com/phpBB2/viewtopic.php?t=67319
http://www.aqugrass.com/phpBB2/viewtopic.php?t=24759
and every article grouped under below
水草情迷 首頁 -> 水草精華
Have fun! Hope not scare you away from this nice habbit...
