There is water too dirty or water quality change bad, need to replace clean water.

还有就是冷却水太脏或水质变坏，需要更换干净的冷却水。

youdao

Change water25% at least every month to keep the water at high quality.

每月至少换水25%，以维持高品质的水质。

youdao

Change water25% at least every month to keep the water at high quality.

每月至少换水25%，以维持高品质的水质。

youdao