How do acids and bases affect the quality of freshwater sources?

C. Acids lower the pH of freshwater and bases raise the pH of freshwater.

If a substance is too basic, it could possibly harm another organism living in the freshwater source. If it's too acidic, it could possibly make unsafe living conditions in that environment. That's why you should always check the pH level in the fish tank and in the pool to see what the pH is. A pH of 6 - 8 is always safe for fish, whereas a pH of 5 - 9 is safe for pools.

Explanation:

Acids: 0 - 6

Neutral: 7

Bases: 8 - 14