What the hell is this

[rvm]

Dunno if this is the right place for this as it isn't an emergency, so I thought i'd put it here.
Anyway, for the last few weeks the corner of my 20g tank has become infested with killer algea! it just grows at an astonishing rate as you can see from the pictures below, also this tank is the only one of my tanks that has a musty smell.
The fish in there are OK, and the water tests fine (nitrate is around 20ppm) I tried a phosphate removing media pack, but that did nothing, so any suggestions are welcome!!

These Photos were taken at 11am:

These ones were taken at 3pm:

And these ones were taken at 11pm

Thanks for any help!!!

 

[daza]

Sounds like the problem Donkey had in this thread. You've probably read it already, but that's all the help I can be I'm afraid!

 

[LoachLover]

hmmm, that's pretty.......weird. Sorry but I can't really be any help

 

[Paul_MTS]

thats what we had in the discus tank at work that was growing on the sand but we just syphoned it out and it went after a while, never grew that fast though.

 

[modernhamlet]

You have cyanobacteria or "blue-green algae". Not good stuff. Physically remove as much as possible and check your water quality. Daily water changes for a few days may help. Here's a brief description...

Grows rapidly in blue-green, slimy sheets. Spreads rapidly over almost everything and usually indicates poor water quality. However, blue-green algae can fix nitrogen and may be seen in aquariums with extremely low nitrates. Sometimes seen in small quantities between the substrate and aquarium sides. Will smother and kill plants. This is actually cyanobacteria. It can be physically removed, but this is not a viable long term solution as the aquarium conditions are still favorable for it and it will return quickly. Treatment with 200 mg of erythromycin phosphate per 10 gallons of water will usually eliminate blue-green algae but some experts feel it may also have adverse effects on the biological filter bed. If erythromycin is used for treatment, ammonia and nitrite levels should be carefully monitored.

source: plantgeek.net

 

[sylvia]

Reducing feeding, more water changes and a period of complete darkness might also help.

 

[rvm]

OK, having read the other thread, I think I'm going to do a blackout for a few days. The water quality in this tank is fine, as it is with my other tanks. The only difference is that this is the most heavily planted tank I have (even though it is still lightly planted compared to some!!) Don't know why I get this stuff in this tan kand none of the others!! I do regular water changes and the maintenance schedule is the same as the other tanks, so there is no reason for it to be any different. Oh well I'll let you know how it has gone in a few days!