White stuff on aquarium back wall?

[CampAquarium]

Can anyone help figure out what this white stuff might be on our back wall? We have been very diligent about cleaning our glass, but admittedly let our back wall go a bit. (Our snails have loved it, haha). Anyway, I noticed recently that patches of the wall seem to be growing or changing to this white-looking stuff. As you can see from the photos, it's appearing in very specific sections. It appears to be eliminating the green algae, but not the coralline. And it has visible snail tracks in it. Any ideas? Some sort of white algae? Bacterial bloom? Dying green algae?

We haven't seen it anywhere else in the tank at this point, but would love to eradicate it soon if it's something harmful.

Our parameters:
Temp: 77.4
Salinity: 1.025
pH: 8.1
Alk: 8.6
Nitrates: 4.6
Phosphates: 0.02
Calcium: 450
Magnesium: 1370

And a couple photos:

 

[blaxsun]

Something feasting on it? (any herbivores?)

 

[CampAquarium]

Something feasting on it? (any herbivores?

I've seen snails crawling over it, but it's hard to tell if they're actually eating it vs. just passing through to get to the green algae. But no- I have not seen any of our tangs etc going for it.

 

[EeyoreIsMySpiritAnimal]

Might be a turf algae. Try some Mexican turbos snails.

 

[CampAquarium]

Might be a turf algae. Try some Mexican turbos snails.

Can turf algae be white? This is definitely white and is appearing in patches.

Whether algae or bacteria-- should we be scraping the back wall to try to remove it? I'm afraid doing that will spread it to the rest of the tank. Fwiw, we are doing our regularly-scheduled water change today, as well.

 

[ReefEco]

Or your could never scrape again! : )

 

[EeyoreIsMySpiritAnimal]

Or your could never scrape again! : )

Yeah, no scraping, you're just stuck with the algae that grows on it...

 

[James M]

Or your could never scrape again! : )

If you pay for it

 

[reefsaver]

Was it all green at one point? Maybe the tank has such low nutrients that the algae is just dying off. Although this is pure speculation.

 

[ReefEco]

Yeah, no scraping, you're just stuck with the algae that grows on it...

Not sure what you mean by this? The CoralWall creates vertical aquascape, which is maintained just like any other rock substrate in your tank. It is no more or less likely to grow algae than your normal rockwork is, and can be maintained with herbivores and proper tank parameters to prevent any algae...