Also, a lot of times even if you test for phosphate during an algal bloom, you'll read 0 - that's because the algae is so effective at taking it up that it sucks it out of the water column, leaving you with a zero result. My personal opinion is that a CuC, while effective at a lot of things, isn't the most helpful at preventing algae outbreaks.
In a new tank, some algae outbreaks are unavoidable, especially as you get used to how much you should be feeding/water changing/etc to maintain a good balance in your ecosystem.
What I can't recommend more is a solid way to export waste from your system. Water changes are one way, so you could up that - but it can be inefficient when you're trying to balance changing too much water (and upsetting the pH/chemical balance of your tank) with not changing enough and not making much of a difference.
Your refugium is a great start - is the caluerpa growing well?
Good flow prevents stagnant areas where algae can easily get a hold - got your powerheads pointed well to minimize dead areas?
Sometimes a temporary blackout can give you a chance to allow your filtration to catch up on the algae growth as well - if it gets real bad, you could black out your aquarium for 2-3 days, whereupon a lot of the algae would die, detach, and be taken up by filtration.
And...of course, water quality - bad water in is bad water out. Are you using filtered water?
