It's funny; I have a very different situation. I've got the Kessil H380 and was using it with chaeto over a 7.5 refugium. Chaeto was becoming white and dying, but only in the middle of chaeto like a hot spot. I've tried everything, changing position, higher .... or away from the refugium, etc. nothing was helping it was too strong, and I think was "burning it" it was not growing at all. A lot of nutrients in the water. So decided to give a try to a cheap light, this one - Amazon link. 25$ ... I run it for about 50 days now, absolutely no changes in pH comparing to Kessil, no more burning chaeto and Caulerpa growing like crazy. I run a Reefer 250 with ATI 4 bulbs + 6 arrays LED from NanoBox so it's a lot of light as well. All nutrients are under control, feeding heavy twice a day with 12 fishes in the main display.
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