Even old dogs can learn new tricks...
In my 30 years in the hobby, I've had quite a bit of success with VHO, CF, and MH lighting. After retiring in 2018, I set up a new tank (Red Sea Reefer 425XL), and got a Kessil AP 700 LED lighting system. The store I purchased this from warned that LED lights are strong for their wattage, and advised that I not set the lights to 100% and to be sure to acclimate new corals.
"Okay, no problem, I've been doing this a while," thought I.
I had my AP 700 set to 70%. Bought some SPS and LPS frags, started them low in the tank, and slowly moved them up higher, day-by-day. Within a couple of weeks, they had all died.
Lowered my max lighting setting to 50% and tried again. Same result.
Okay, it was a fairly new tank, and nitrates were high and phosphates were low, so maybe that was the problem. Spent some time fixing that, and tried again. Same result.
Raised the lighting max to 60% and focused on softies for a while. Got a Kenya Tree Coral (KTC) frag, and that did fine. Correction, that ran amuck in my tank and was EVERYWHERE! Well, except for the rock peak where I put a RBTA (hey, I gotta have a RBTA!). Now I have eight.
It's been a few years, and I was really tired of all the Kenya Tree everywhere, so I spent an afternoon removing several hundred KTC frags, and cleared 99.9% of them out of the tank (there's still a few small offshoots that I missed, but I'll be getting them the next time my hands are in the tank!).
My water parameters are perfect, so I figured I'd test the water with a couple of SPS frags. No bueno!
So, I bought a PAR meter (Apogee MQ-510) to see what was going on with the light in my tank. I should have done this YEARS AGO! At the full 60% lighting (which is only on 3 hours a day as the cycle ramps up and down), the lower parts of my tank were in the 30-40 PAR range, and the upper parts 110-140 PAR range (with glitter lines sometimes shooting the PAR up to the 160-180 range).
Well, no wonder my SPS frags were failing! Unless they were at the very top of the tank, directly under the lights, they wouldn't get even the minimal amount of light they need to survive (and the only spot meeting that specification is occupied by a bunch of RBTAs!).
Today I set the Kessil program to 80% of max intensity, and many of the PAR readings were in the 100-150 range (although not lower in the tank). After a couple of days, I'll be bumping the setting up to maximum intensity (100%) and see what the readings are then. After that, I may increase the length of the max photoperiod.
I try very hard to not be a "gadget reefer," but after all these years I've discovered a PAR meter is a needed tool in this hobby (especially with LEDs)!
Kevin
In my 30 years in the hobby, I've had quite a bit of success with VHO, CF, and MH lighting. After retiring in 2018, I set up a new tank (Red Sea Reefer 425XL), and got a Kessil AP 700 LED lighting system. The store I purchased this from warned that LED lights are strong for their wattage, and advised that I not set the lights to 100% and to be sure to acclimate new corals.
"Okay, no problem, I've been doing this a while," thought I.
I had my AP 700 set to 70%. Bought some SPS and LPS frags, started them low in the tank, and slowly moved them up higher, day-by-day. Within a couple of weeks, they had all died.
Lowered my max lighting setting to 50% and tried again. Same result.
Okay, it was a fairly new tank, and nitrates were high and phosphates were low, so maybe that was the problem. Spent some time fixing that, and tried again. Same result.
Raised the lighting max to 60% and focused on softies for a while. Got a Kenya Tree Coral (KTC) frag, and that did fine. Correction, that ran amuck in my tank and was EVERYWHERE! Well, except for the rock peak where I put a RBTA (hey, I gotta have a RBTA!). Now I have eight.
It's been a few years, and I was really tired of all the Kenya Tree everywhere, so I spent an afternoon removing several hundred KTC frags, and cleared 99.9% of them out of the tank (there's still a few small offshoots that I missed, but I'll be getting them the next time my hands are in the tank!).
My water parameters are perfect, so I figured I'd test the water with a couple of SPS frags. No bueno!
So, I bought a PAR meter (Apogee MQ-510) to see what was going on with the light in my tank. I should have done this YEARS AGO! At the full 60% lighting (which is only on 3 hours a day as the cycle ramps up and down), the lower parts of my tank were in the 30-40 PAR range, and the upper parts 110-140 PAR range (with glitter lines sometimes shooting the PAR up to the 160-180 range).
Well, no wonder my SPS frags were failing! Unless they were at the very top of the tank, directly under the lights, they wouldn't get even the minimal amount of light they need to survive (and the only spot meeting that specification is occupied by a bunch of RBTAs!).
Today I set the Kessil program to 80% of max intensity, and many of the PAR readings were in the 100-150 range (although not lower in the tank). After a couple of days, I'll be bumping the setting up to maximum intensity (100%) and see what the readings are then. After that, I may increase the length of the max photoperiod.
I try very hard to not be a "gadget reefer," but after all these years I've discovered a PAR meter is a needed tool in this hobby (especially with LEDs)!
Kevin
good old British saying 
