Algae after adding new Live sand

[mjs]

5 year old established tank with corals and limited fish.
I added 25 lbs of new live sand to a 90 gallon set up.
The tank has exploded with stringy, redish algae.
Ph is slightly high (8.4) and other parameters are in line.
Is a major water change the best remedy?

 

[burning2nd]

excess Po4 I suspect
might be undetectbul due to take up speed...

WAter changes... Depending on your self and your setup will determin if you can do 60g water change or a 20 at one time...

but removal via waterchange is always a winner