bleach treatment story, with many roots

Well, my tank's hair algae state had progressed from "a little bit",
sped straight on by "annoying", and came to rest at "choked". While
twirling my little bottle brush around among my Rotala indica to
remove algae, I decided enough was enough, and that it was time for
the bleach treatment.

My tank (nominal 50G, 120W fluorescent lighting, gravel substrate,
yeast CO2 between 10-30ppm, liquid additives in the form of the
iron-rich Flora Pride, and extra homebrew iron and potassium) is
populated mainly by Rotala indica, with a fair amount of Hygrophila
polysperma, and a few fish. I got a small tub of bleach solution (1
cup Clorox, 19 cups water), went to pull up a bunch of Rotala, and was
rather surprised when nearly a square foot of gravel started to come
up with it.

Half an hour, lots of cloudy water, a dulled pair of scissors, and a
lot of gravel down my Dispos-All(tm) later, I have made an important
discovery: my gravel was basically one giant compacted root bolus.
Some of the roots were over a meter long. I basically had to pull up
bunches as far as I could by hand, brush off gravel, and get in there
with the scissors to snip roots. After all the plants were out I was
able to pull out the rest of the (now detached) roots and throw them

A week later, I have had no plant or fish losses from the bleach
treatment. I rinsed the hell out of the plants after treatment with
water and a lot of sodium thiosulfate - I used up about half a 20oz
bottle of sodium thiosulfate. Note to people considering this: be sure
to have a lot of this stuff on hand, because running out in the middle
of pulling up plants and shuffling them around and rinsing them is
probably a drag.

I have yet to isolate what conditions are allowing the hair algae to
proliferate. I have two varieties of the stuff, one very soft feeling,
producing long (up to 6" long) strands which tangle, greyish green in
color, and one which feels like rough wool to the fingers, which makes
short bright green threads. My water values: pH ranges from 6.6 to
7.0, alkalinity 3.5-4dKH, ammonia and nitrite unmeasurable, nitrate is
below 10ppm, iron is about .1ppm, phosphate is under .1ppm. I change
between 33% and 50% of the water weekly. My plant growth is good but
not spectacular; I figure if I can get the growth to improve a bit the
vascular plants will outcompete the algae better than they are now.
Suggestions are appreciated. I'd even consider tearing down the tank
and doing a sand and/or soil substrate if people think that's the
blocking factor.


Matt Rhoten, mrhoten at oz_net, mattrh at microsoft_com, mrhoten at cs_stanford.edu.
Speaking for myself, not my employer.
Resistance is futile. You will be assimilated.