No matter how much (por más que, por mucho que)

To express "no matter how much," use por más que or por mucho que.

When describing an experienced reality or a known fact (like an ongoing or past action), use the indicative.

No matter how much we used the pesticide, the pest wouldn't disappear.
Por más que usábamos el pesticida, la plaga no desaparecía.
No matter how much fertilizer they pour, the field is not fertile.
Por más que echan abono, el campo no es fértil.

When referring to a hypothetical situation, a future possibility, or an unknown outcome, use the subjunctive.

No matter how much you use the pesticide, this pest will destroy the harvest.
Por mucho que uses el pesticida, esta plaga destruirá la cosecha.
No matter how much they use the expensive fertilizer, the seed does not grow.
Por mucho que usen el fertilizante caro, la semilla no crece.

Notice how the mood changes the focus from a known fact to a hypothetical scenario:

No matter how much they removed the weeds with the shovel, they always grew.
Por más que sacaban la maleza con la pala, siempre crecía.
No matter how much you dig with the shovel, the weeds will return.
Por mucho que caves con la pala, la maleza volverá.