So having gone with the AI Sols, I wanted to see how well they were lighting the tank. The goal was always to have darker areas and more well-lit areas, I didn't want to blast everything in the tank with bright light, I wanted something that looked a little more natural.

So I started looking around for PAR meters - there's a couple of DIY projects but nothing calibrated and "ready to go", so I caved and looked at the professional ones. Apogee's meters seem to be the normal...