Nitrate isn't always the enemy carefully; low yet detectable tiers can enrich coral colour

https://delta-wiki.win/index.php/Coral_Care_one_zero_one:_Tips_for_Keeping_Your_Reef_Aquarium_Healthy

Nitrate will never be the enemy moderately; low however detectable levels can enhance coral color and growth with no fueling nuisance algae blooms.