In small tanks it is usually fastest, cheapest, and least
painful, to just break it down and start over.

Remove the fish. Treat as if they were new... Prepare 3
pots of clean, fresh, water NOT from your tank. 1 dosed
with Malachite Green and Formalin, the second with salt at
about 30ppt, and the third clean fish-happy water.

Net fish from the tank into in the Malachite green, let
stand one day or two, then net them for a few second dip
(tetras max 2 seconds, beefier others 4-5) in salt water,
then let them into the clean water for holding.

Use a different net to take them from the tank to the green,
and from the green, through the salt, into the new water.
Or, you can bleach the net while they sit in the green.

Treat any plants that aren't too involved in chlorinated
water. Save some by cutting badly involved leaves as close
to the main stem as possible. Some can be soaked briefly
(2-4 minutes) in a solution 1 part household bleach, 19
parts water.

See:

http://fins.actwin.com/aquatic-plant.../msg00766.html

Bleach all the hardware, including your bio-filters.

Discard the gravel and replace, unless it is epoxy coated.
If so, you can bleach it too.

Once empty, clean the tank well, bleach it too.

Reestablish the tank, as new.

Return the fish and plants, use Amquel and/or water changes
to keep Ammonia down until the tank cycles again. If you
use Amquel (or similar) don't use carbon until after the
cycle is complete.

Now...

Algae is in the air. You will likely get inoculated with
various forms, over time. Make sure you limit your inputs
(try the PMDD regimen, strictly, Fe testing and all), and
maximize outputs (water change/harvesting), this time. Try
keeping Hornwort.

***********************************
Brian Anderson wrote:
I hope someone has an idea on how to get rid of this crap. My 12 gallon
aquarium has all low light plants that are growing very well and there is
almost no other algae accept for this thick fuzzy stuff.
I have 2 ottos and one pleco that keep the tank spottless but don't do
anything with this algae. I bought a Siamese algae eater hoping it would do
something. He nibbles on the algae but doesn't do much. I manage to barely
keep it under control by picking if off the plants and using an algae killer
AlgaeFix, but it still keeps growing. I have lowered my phosphate level
down to minimum. The tank has mostly tetras with ph around 6.6, nitrate,
nitrite, ammonia are all normal. I don't use CO2, just liquid fertilizer
once a week.
Any ideas would be greatly appreciated.

Brian