"Chris_S" wrote in message
...

Here are some specs:

- Tank 100G
- DIY CO2 injected into Heater module on 2226 return, 100% diffusion.

Is this yeast CO2? If yes, then it's highly recommended to use a compressed
system on tank this size. But with your lighting, you might get away with a
yeast system.

- (2) PowerCompact 65W 6700K lights.

That's only 1.3 W/g. It shouldn't be that hard to stop the algae at this
lighting. In other words, to make light as the limiting nutrient for your
plants.

- Test Kits: LaMotte, Salifert, Seachem.
- Flourite mixed into gravel with some tetra sticks.
- I have used Seachem Flourish, Potasium, Iron adders, and Vitragro, etc.

Have you used Flourish and potassium at the same time? Or were they added
sort of ad hoc? You don't really need to use any other commercial additives
with Flourish. Just the macronutrients.

- Plants, more than I can name. the swords got so big I finally had to
get
rid of half of them. Crypts, some large ferns, apogeton, Valliseria, java
moss, lotus, some bush type plants I can't remember.

Nitrates: 15PPM
Phos: 0.5 PPM
GH: 6 deg
Iron: 0.1 PPM
CO2: 25PPM

Have you measured it both in the morning and in the evening?

Like I said this new tank is only 6 weeks old, and I am still working on
getting the iron back up. The tank is weak right now on Nitrate and Iron.

An iron test is not really a good indicator or iron availability for plants
for various reasons. Watch the new leaves of your fast-growing plants. If
they are pale or red, add more Flourish. It's not unusual to add several
times recommended amount of it. Do the nitrates naturally increase or
decrease? If they increase, that's not a good sign. Even at your lighting, I
think the plants should be able to overall reduce the NO3 from the water
column. It may not be necessary to add PO4, though.

I keep my CO2 fairly high. But if it slips for some reason,
I get an almost immediate algae outbreak, even if the CO2
is still above 20 ppm.

Yeh of course, that's because your nutients are so high.

But the other nutrients are still high with adequate CO2. Why doesn't the
algae grow with high CO2?

any BBA. After I got BBA 5 years ago, it makes no difference how good or
bad the water is. The BBA is always there regardless. That's why I've
given up on water control for BBA.

The most precise water control in the world wouldn't work if you don't think
about the plants. It's not the water parameters the algae responds to. It's
plant health. Again, I'm not sure how it's connected. It doesn't seem like
you've really tried focusing on plant health/growth before. Doing one thing
for the plants will not stop algae. The plants have to get enough of every
nutrient at the same time.
__
Alex