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BGA, H202, KH, Ph and CO2...

1) I have BGA and have been battling it for some time. The tank (55 
w/overflow + no media trickle) has quite a high fish load (5 Discus, ~30 
tetras, a few Otos and a few SAEs) and I had a significantly high nitrate 
level. To reduce the nitrates, I built a coil denitrator and the level 
dropped from about 40ppm N-NO3 to about 4-5 N-NO3 (LaMotte). Still not much 
of an improvement on the BGA.

There is no measurable level of PO4 (LaMotte, Low range). I use Flourite 
and CO2. Also, the tank has LOTS of plants:
- 15-20 Telenthera,
- 10 Scarlet Hygro,
- ~30 strands of Rotala Indica,
~30 strands of Rotala Wallichi,
~ 20 strands of something that looks like a "succulent",
- several small clumps of Hygro Difformis (doing poorly, btw),
- A couple of Amazon swords,
- A couple of melon swords (not really growing, but not dying either),
- 2"sq of  micro sword (BGA loves this as a home),
- And several fast growing strands of ???

I then noticed that when I did not have as big of a water change, the BGA 
would slow down quite a bit. The water I change with is RO water (I 
sometimes add CaSO4, CaCl and Epsom Salts to add some hardness back in). 
Nothing measurable in the RO water (NO3, PO4, etc...). I also keep the Kh 
around 3 DH (Tetra) by adding back in some CaSO4, MgSO4, CaCl, and baking 

Someone then mentioned (at Albany Aquarium) that my discus would do fine at 
78 degrees (and that the plants would grow better) than at the 84 I was 
keeping the tank at. I lowered the temp and a few of the plants started 
growing better (Melons, for one), but the BGA still persisted.

SO, with the discussions going on using H202 for BGA oxidization, I tried 
it and saw only a little improvement. I started out with 1 TBSP/Day and 
moved to 4 TBSP/day over a period of four days. Little (but some) 

Even if the H202 is a temporary fix, I would still like to get to the root 
cause. Next thought was circulation and CO2. Added a very large power-head 
last night to push water towards the bottom (that is where most of the BGA 
seems to like it now). We'll see what impact that has. CO2 led to my next 

2) I am using Dave's set-up. The problem with the set-up is that I am 
always having to adjust the flow (but set that aside). I have the Ehiem 
diffuser (which I also do not like, small bubbles get large after a week 
and I need to constantly clean it) feeding into a smaller power head which 
only pico (smaller than micro) bubbles come from the eject point, and seem 
to mostly dissolve in the water. So I figured with 2-3 bubbles per second 
and almost all of it dissolving, I would have a good level of CO2. Right? 

pH is a "hare" over 7.0 (Tetra)
KH is right at 3.0 (Tetra, double filled, double drops for better 

This gives me a CO2 of somewhere between 6-9 ppm. Not a whole lot???

How do I increase my CO2 levels??? Increase the number of bubbles per sec? 
Better reaction chamber (although it appears as though I am getting it to 
dissolve pretty well now), increase the KH by adding more Baking soda?

Any thoughts are appreciated.


- Jeff