We'll maitain the temperature as same as the tank.

We'll maitain the temperature as same as the level of the tank.

首先，as same as 这个说法，在非正式英语或口语中是有的，但这是不规范的用法，因为 as...as... 和 same 意思重叠，违背逻辑，应该使用 the same ...as，或 as high as。

其次，“温度与......一样高”，“温度”这个词语，可以用替代词 that 代替，不用 level。改为：

We'll maitain the same temperature as that of the tank.

We'll maitain the temperature as high as that of the tank.