will 10k pc make my tank look brighter than 50/50pc

[Delphinus]

I don't know. Maybe. The thing with actinics is that they're dim by comparison, so I'd guess that a 50/50 will appear less bright than a 10k. My guess is that it might appear a wee bit brighter, but don't expect too much, it's the same wattage in the end. But this is just a guess, the only way to be sure is to take the plunge and give it a try.