Firstly,i am not 高人, i am too short.
1.
Reason: According to your pictures,there are too much fish and that is the main reason why you have some藻。
WAY:You should identify what types of the 藻 are and solve the problem.Most of the solving way is that you should change the water for 17% to 20% for a week regularly until the situation be controlled.
2.
Reason:When you buy the plant ,there are some snails attached
with the plant.
WAY:~~You should kill them cruelly as soon as you seen .
~~You also can buy the 蛙蛙 which only eat the snails effectively.
But you have too much fish which i am not suggest you buy.
Hope this can help....
唔知有冇grammatical mistake呢?