Learn Spanish (Latin America): El tanque de los tiburones viene a perder veinte litros de agua al día. - The shark tank loses roughly twenty liters of water a day.

Using the structure venir a followed by an infinitive (perder) adds a sense of approximation. It tells us that the tank loses roughly or approximately twenty liters. If you just used the simple present pierde, it would sound like an exact, precise measurement.

Could I just use a word like aproximadamente instead of this viene a structure?

Absolutely. You could say pierde aproximadamente veinte litros or pierde más o menos veinte litros. The venir a + infinitive structure is simply a native-sounding alternative that Spanish speakers frequently use to express estimates or summarize a final result.

Why does the sentence use al día for 'a day'? Could I say por día?

Yes, you can use por día, which is also very common and correct. However, using a plus the definite article (which combines into al for masculine singular words like día) is the most traditional way to express rates and frequency in Spanish, such as al mes (a month) or a la semana (a week).

Does viene a still carry the literal meaning of 'comes to' in this context?