KH and hair algae?

[MattD004]

I was wondering whether KH has anything to do with hair algae? I went on vacation and came back to find my tank's KH values out of whack.
Vol. 65g +10g sump
Phosphates: trace
Nitrates: undetectable
Nitrites: undetectable
Calcium: 550 ppm
Alk: 2.13 me/q

I did a 25% water change, and am trying to slowly bring my alk back to normal. However, my corals look like they have grown but my tank has a sudden explosion of hair algae. I thought this was a phosphate problem? But these seem within control. I'm running carbon on the water. All tests were done with salifert test kits and also at the local LFS confirming the results. What do I do?

[Randy Holmes-Farley]

I was wondering whether KH has anything to do with hair algae?

Only to the extent that low alkalinity will reduce growth of calcifying organisms (coralline algae, hard corals, etc.), and that lack of growth may have reduced their nutrient uptake, leaving nutrients for algae.

A big growth of algae will reduce measurable phosphate, so it is still a good plan to export more phosphate. :)

Most likely, the alk is unrelated to an algae problem.