Added Carbon. Then ALK went up?

[leighton.bingham]

So yesterday I added more REEF SPEC Carbon to the front of my sump. Check the ALK this morning, and it was up 1.1 dKH sitting at 9.5dKH. It's normally at 8.4dKH and I dose 11mL of Redsea Foundation B to keep it nice and steady at 8.4dKH. Salinity is at 1.025 Ph 8.2 Cal 350 and Mag is at 1440 temp 77.9

Would the carbon cause it to raise that high or not use that much ALK overnight?

 

[Randy Holmes-Farley Verified Community Expert]

I don't believe the GAC can itself impact alkalinity to a significant degree, but if you suddenly made the water less yellow, the increased UV and blue light hitting corals might be stressing them and might reduce the calcification.