How do you know how much light you should have without a PAR meter?

[Kayvon]

I have never known how people know whether they should turn their lights up or down by simply looking at the corals. I have never been able to get fast growth of my corals like I know I should be. What indicators do you use to tweak intensity and spectrum in your lights?

 

[Crabs McJones]

I have never known how people know whether they should turn their lights up or down by simply looking at the corals. I have never been able to get fast growth of my corals like I know I should be. What indicators do you use to tweak intensity and spectrum in your lights?

Start low and slowly work your way up until it looks like your corals are getting annoyed and then dial it back a little bit. Otherwise you can check with local reefing forums. Alot of times they have a par meter that they loan out to users of good standing. That's what I did.

 

[Donovan Joannes]

There are quite a number of good app for your mobile phone that measure light intensity. It might not be that accurate but at least you know your intensity at water surface to give you some ideas how intense your light are.

 

[Salty1962]

Lux meter.