Brown Algae takeover in established tank

[OceanLuv]

Hi All,

I have a recently set up 210 gallon (250 w/ sump) - i upgraded from 75g and moved all my rock, water, fish, etc about 6 months ago. I haven't had a problem with algae - I've been dosing, and keeping my nitrates below 10. 3 week 20% water changes. Salinity 1.025.

I recently added 15 lbs of "cured" live rock about 2 weeks ago, and we are now having a full diatom takeover. This has been slowly coming since we got the rock but now it's just crazy and UGLY!! Today it's been the worst its been.

I want some opinions - Is this the rock? and should I take it out or wait it out?

Thanks!!

[Samper]

I'd venture to say that your rock wasn't fully cured and with the die off you may be seeing a tiny mini cycle. 15lbs of rock isn't much for a system of that size and might not even cause your nitrate reading to go higher than it has been but I'm thinking that is what's causing it. I'd wait it out if if two weeks passes and you're still seeing it...we'll start thinking of some other options. You are using RO/DI right?

[OceanLuv]

Thanks for answering Samper ... yes, I use RO/DI water. I couldn't think of anything else other than a mini-cycle as well. i hate waiting it out because i hate algae!! I know - who doesn't? I'm also annoyed that the LFS sold me uncured rock saying it was cured.

[Ninong]

I wouldn't be too concerned if I were you. The diatom bloom should dissipate within 10 days to two weeks once silicate is exhausted.

[Reefland]

I'm also surprised that this small amount of new rock would cause it, however as Ninong mentioned I wouldn't be overly concerned as it will pass.