Light/quantum meter question

[naturebatslast]

Is it me, or is the quantum meter way touchy? I'm having a hard time getting repeatable results and getting the sensor level. When repeating measurements, I can get very general ballpark (a big ballpark) results, but no 2 measurements are the same.
It seems that even a 5 or 10 degree tilt on the meter can influence the reading significantly.

 

[Reefried]

You will NEVER get the same results cause the water is always moving, but the best way to get the best readings are to shut off all pumps/powerheads and ball back your return as much as you can (if you shut the return off the water will drop an inch or more and not give you the same results as when the pump is on)...and with your arm as still as possible get the lowest and highest reading for that location (eg. 6 inches below surface) and average them out...the reading always changes because as the water moves on the surface the amount of light going through it to the sensor changes constantly....ans as ageneral rule if you get 150's or higher on your sandbed you can keep pretty much anything you want....go to melevesreef, and go to the site diorectory he has some good info under the PAR section...good luck..and even though it jumps around a lot you get an idea of what corals get in which spot in the tank...I have a Atlantis Purple bonsai that was coloring down with my new lights and I found out that in that spot it was getting a PAR reading of 1000 which is really high, so I moved ot to a spot which gets about 450-600 and the color is comming back...hope I helped a little bit....oh and if your reflectors and or glass is dirty it will effect results by a lot

 

[naturebatslast]

Thanks, I was aware of the water measurements issues. It's just the degree of variance between 2 readings are so drastically different, for air or water. The sensor mounted on the plexi with the screw also makes it really difficult to get it level.

 

[naturebatslast]

I'm curious how others made measurements.

 

[MikeG]

I'm curious how others made measurements.

I took a lenght of PVC and cut a slot that the piece of acrylic that the sensor is screwed to would fit into. I actually cut a slot evey six inches and then took measurements at all of these depths. Worked quite well. Sensor was basically in the same position every time. I just used my table saw to make some cuts and make sure they were at 90 degrees.

 

[Reefried]

I took a lenght of PVC and cut a slot that the piece of acrylic that the sensor is screwed to would fit into. I actually cut a slot evey six inches and then took measurements at all of these depths. Worked quite well. Sensor was basically in the same position every time. I just used my table saw to make some cuts and make sure they were at 90 degrees.

I did that too, I got it from Meleves site and thats why I told Nature to check it out lots of good info

 

[MikeG]

I did that too, I got it from Meleves site and thats why I told Nature to check it out lots of good info

I figured someone must have done that by now. It did work well. I mentioned the same method when I had the meter about a year ago as well. Definately makes things more consistent.

 

[JayM]

I took a lenght of PVC and cut a slot that the piece of acrylic that the sensor is screwed to would fit into. I actually cut a slot evey six inches and then took measurements at all of these depths. Worked quite well. Sensor was basically in the same position every time. I just used my table saw to make some cuts and make sure they were at 90 degrees.

why didn't you add it to the meter when you passed it along?