2 quick questions about PAR testing

[cvrle1]

Have some time to figure out height that I will need for my lights, but have 2 basic PAR questions

1) I should set my lights at highest setting I will use during the day (ex: 50% blue, 50% white), and take PAR readings. Correct?
2) Does it make any difference if salt vs fresh water is used? Reason I ask is because tank is on the floor in the garage, and I will move it many more times before it is ready for rocks, sand and saltwater. I dont want to mix saltwater that I will dump after PAR reading are done (dont have anywhere to store it). Waste of 100G of salt and RODI water.

I know I could just wait till tank is setup, but since I have time I wanted to use it to dial in lights as best as possible.

Thanks

 

[Vinny Kreyling]

1- Correct
2- No idea but why not?
You can let us all know later.
Your readings will change later with water movement according to Dana Riddle.

 

[cvrle1]

1- Correct
2- No idea but why not?
You can let us all know later.
Your readings will change later with water movement according to Dana Riddle.

Thanks very much. I was thinking about water movement, and know that it will change readings. Issue is that most of PAR meters look to have issues when water movement is added to the equation (no pun intended) and reading can be way off. Several folks said their reading were off by 200+ PAR with water movement. From what I remember water movement lowered PAR by 10% or something like that. Will try to dig up that info from Dana.