White Algae / Fungus!?! Help!

[sumocopter]

Hi folks,

I have a problem with some nasty white stuff which is spreading across the substrate in my tank, it seems to be happy at home on bogwood and some stones too!

I was unable to tend my tank for a couple of weeks and when I got back it was just beginning, it got alot worse quite quickly over a period of a week or so. I did a 50% water change and gravel vacced all of the white stuff that i could see without deconstructing the aquascape 9 days ago. Now almost the whole substrate is covered again.

In this whole process I have lost 2 firemouths, the rest of the fish seem short of oxygen. Just today I have noticed one of my remaining two firemouths seems to have fungus around his gills.

The tank is well mature and has been very stable with no water stats problems for months and months.

Tank info today:
Size: 450l
pH 7.6
Ammonia 0.5ppm (normally zero)
Nitrate 0
Nitrite 0

Inhabitants:
1 Green Severum
1 Opaline Gourami
2 Firemouth Cichlids
2 Angelfish
2 Black Phantom Tetras
8 Pentazona Barbs
1 Female Siamese Fighter
3 Corydoras
2 Plecostomus

Does anyone know what this is and how to shift it?

Cheers

 

[Twinklecaz]

Ok I don't know much about this but is it possible it's limescale rather than algae? Just a thought.

 

[sumocopter]

I am in quite a hard water area but I use 50% tapwater and 50% rainwater. I've never heard of limescale in a tank before? Can it build up this quickly? I thought it was the nasty hard stuff that built up in your kettle over years?