Rent the newest Apogee MQ-510 Par meter specially designed to measure the blue light emited from LEDs. Rental price starts at $15 and shipped directly to your door. Don't settle for cheap inaccurate equipment anymore. Find out exactly what par your coral needs.
$37/day plus shipping both ways. A large deposit is required to secure the meter, so there is that. But you would get that deposit back assuming the unit is shipped back in the same condition.