White growth on live rocks

[Rovii91]

Hi all, new to the hobby.
Ove got a 30Gallpn tank with approx 17kgs of live rock and live carab sand.

I'm running a protein skimmer, fluval 207 cannister and salinity is at 1.024 at 28 degrees.
But I've just noticed this smooth looking white growth on some rocks.

 

[vetteguy53081]

This appears to be a sponge material. Lift rock out and using gloves, pull by hand and even a pick and discard and finish by brushing rock with a firm toothbrush and hydrogen peroxide

 

[Rovii91]

I

This appears to be a sponge material. Lift rock out and using gloves, pull by hand and even a pick and discard and finish by brushing rock with a firm toothbrush and hydrogen peroxide

Should have mentioned this earlier, it's only 1 week old with seeded live rock - does that make a difference