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Questions about CO2, Flourish Iron, Algae

Hi there,

This is my first post to the list but I've been reading it for a while. I
live in Brisbane, Australia and currently have three tanks, the largest
being a 55 gallon which has many plants and three adult discus. I have seven
SAEs, three otos, a royal whiptail and a farlowella also in that tank. The
plants I have are various Echinodorus, some Val, Ambulia, Wisteria and a
Crypt. The substrate is vermiculite/soil covered with "river sand" (about
1-2mm). Temperature is 30 degrees C, pH 6.5. Water is relatively soft.

I have recently been trying to get good plant growth and have read pretty
much all of the info at The Krib on various topics related to plants.

I have three 36-watt fluoros, one of which is a Triton and the other two are
marketed here as "Power-Glos" but are actually Sylvania Aquastar 10000s. All
T8. These are on for 12-13 hours per day.

I have three questions:

I have an algae problem (surprise!). I have two "strains" of algae - one is
a sort of brown hairy, cotton wool-like fluff that grows throughout my
echinodorus tenellus. I have to manually remove it. The other (which i'm
more concerned about) is a sort of black "coating" that all leaves on my
plants older than a couple of weeks get all over them. It covers the rocks
too. The only fish that seems to eat it is the royal whiptail, and he can't
do the entire tank! What is this algae? Is it diatoms? What should I do to
remove it? I fertilise with Flourish once a week and Flourish Iron is added
every day, as is Flourish Excel which I am testing. I also have iron-rich
clay balls inserted next to each plant in the substrate for additional iron.
The black algae-covered plants look awful and I have to scrub the algae off

That brings me to question number two. As I mentioned, I add Flourish Iron
daily (3mLs). The thing is, it seems to "disappear" very quickly. I have a
Dupla Fe test kit and it registers relatively high immediately after I add
the Flourish Iron, but only 2-3 hours later it registers zero. Is this
normal? Is this happening because the plants are absorbing it? If so, should
I be adding more?

The last question is about CO2. I plan to get a proper CO2 system soon but
in the meantime I thought I'd experiment with DIY yeast. I believe from
reading the Krib that the extra growth from the CO2 will help the plants
thrive and outcompete the algae. I set up the bottle and initially I have
been simply letting it feed into the Venturi inlet on the powerhead.
(Powerhead is purely a polishing filter/water circulator. I also have an
Aquaclear 200 and a canister filter)
It is definitely working, I am seeing the plants bubble which they were not
doing before.
However, the yeast seems to be *extremely* active and bubbled so much that
the bubbles completely filled the bottle and started pumping into the tank!
Not good. Why would this be happening? Perhaps I put too much yeast in the

Thanks for any advice you might have. Sorry for the lengthy post.


Rob Keniger