What the???

[rpate2]

Can anyone tell me what this white growth might be? It's hard and white and slowly spreading round my LR.....

Tank Parameters:
Ammonia: 0
Nitrite: 0
200l / 50gal
Nitrate: <5
PO4: 0.25
PH: 8.1
KH: 9.4
Salt: 1.025
Ca: 440

Dosing: 4.1ml Red Sea NOPOX daily
Light: 156w T5 2xwhite, 2xblue - mar 2017 bulbs + 40w blue/white LED

SUMP:
Large Skimmer
Live rock in sump (no light)

Maintenance: 10% Weekly Water Change, sand syphon, LR blasted with turkey baster prior

Stock:
2 X small Clown Fish
1 X Red Fire Goby (Firefish)
1 X Yellow striped Cardinalfish
4 x Green Chromis
1 x Foxface
1 x Domino Damsel

CUC:
1 X Turbo Snail
5 X Nassarius snails
1 x Sea Urchin
2 x hermit crabs

 

[Brewman1987]

To me it looks like your clean up crew is doing its job. Notice the random patterns and it looks like the snails were hungry.

 

[Conman33]

If it looks like growth it could be a sponge I had what looks like the same thing and it eventually took over everything

 

[Jason mack]

+ 1 for sponge

 

[94Roarge]

+2 sponge

 

[wkscott]

Don't you like so many different answers? My guess is also your cuc. Specifically your urchin. When they eat, their rasping beaks can scrape and remove a thin layer of the live rock, right down to the white of the rock.

 

[rpate2]

The white stuff is hard like rock so I'm fairly sure it's not a sponge, but truthfully I know very little about sponges.

I hadn't thought of the urchin, but he lives just inside that cave where the white stuff is thickest and only comes out at night so I rarely see him at work. Come to think of it I guess it all started a couple months ago right around the time he went in....[emoji3][emoji3] thanks guys!

 

[Brewman1987]

The "white stuff" is your rock, underneath all the algae and build up. Clean up crews do just that and watch out for corals, i had my urchins chomp on some coral in the past. Also if it were a sponge it would be more transparent and have a more 3d appearance.

Dan

 

[Angel125]

+1 on urchin.

 

[Reef Stu]

You can see the star like scraping pattern from your sea urchin feeding. May I urchin leaves the same pattern.

 

[Reef Stu]

*my... not "May l".