Optimal PAR Readings with LED Lights

[asid61]

HOW MANY CREES? And is it a complete fixture or a DIY?

 

[webdizzy]

HOW MANY CREES? And is it a complete fixture or a DIY?

TWO complete fixtures with 20 bulbs each, half white and half blue.

 

[asid61]

40 leds on a 75 gallon tank is way too little, eve with Crees. But even running them at 50% or so, 50 PAR at the top seems a little suspicious. There is either something wrong with the meter or the leds, or probably just the water.

 

[webdizzy]

Water parameters:

SG = .024
Nitrate = 15 (it was 0 a week ago -- evidently still having issues there)
Phosphate - .04
pH - 8.1
Calcium = 310
Alk - 6.4

I don't normally dose anything. Just try to keep nitrates at 0 and phosphates down.

I'm afraid to adjust the lights at all now -- not knowing if they're causing the bleaching or if the par meter is accurate. Right now I have the whites at 25% and the blues at 50%. Seems like I should be able to have the tank brighter than it is. . .

 

[asid61]

Calcium and alk seem very low, and 15 nitrates is pretty high for SPS. Phosphate looks a little high too, but that's just me.
Run the leds about 50% higher so that blues are at 75% and whites at 40%. Increase blues 5% per week till you have it down. Whites should remain proportional, so like 2-3% for whites.

 

[acabgd]

Water parameters:

SG = .024
Nitrate = 15 (it was 0 a week ago -- evidently still having issues there)
Phosphate - .04
pH - 8.1
Calcium = 310
Alk - 6.4

You've had quite a dramatic increase in nitrates in a short period of time. Additionally, your Alk is really low - question is was it any lower during the last week or so. Your Calcium is also low.

Actually, with such parameters lights would be the last thing I would look at.