[rtparty]

To be completely honest, there is NO way of estimating PAR. It just isn't possible. There are so many factors that determine PAR that an estimation is not possible. Sure someone could come here and have the same setup and say they are getting 300 PAR 6" under the water surface and then you think you should be close to that.

Then in reality you test and only come up with 150 PAR. Why? Shouldn't they be close? No, they shouldn't be. Flow, rockwork, and many other things contribute to an overall PAR reading.

Let's not even get into the fact that the average PAR meter used in this hobby is under reading LEDs. Some numbers have shown they may be off by more than 40%.

We could even talk about how your optics are creating hot spots in the tank and PAR might be 100 or so and moving the sensor an inch to the right and all of the sudden you are registering 250 PAR. Which reading is correct?

Just too many factors.