No questions, just some observations.
Back in April, I received some plants with this, which I believe is commonly called Staghorn:
Have never encountered this in all my years of planted tanks, prior to April when I received some plants with a tiny bit of it. Repeated and heavy H2O2 spot treatments eventually eliminated what I could see. But some escaped, and spread to other tanks as well.
It has been a minor nuisance ever since. Typically a bit of it appears only in areas of low flow, when I let a tank become too overgrown. A good trim and it's gone again.
However, it recently turned into a plague in my 46G, that grows everywhere
. I looked for a picture that matched this algae exactly, and found the above picture in a guide on the Method of Controlled Imbalances (MCI).
MCI says this algae is caused by an imbalance in the Ca/Mg ratio, with Mg being too high. There may be some truth in that, as I started adding GH Booster in this tank shortly before this algae became troublesome, to see what effect it would have given that my tapwater only has a GH of 2.
While it's possible that the addition of extra Ca/Mg increased growth, therefore causing some other nutrient to become limited, I have seen no noticeable increase in plant growth. Significant increases of all other nutrients, well above EI recommendations, had no affect on the growth of plants or the algae. And pressurized CO2 levels are good, with a greenish-yellow drop checker, and near the point where a few fish gasp.
I plan to continue experimenting with the GH booster and other parameters to see if I can better determine what's really spurring this algae to become so aggressive, but need some way to keep this algae at manageable levels in the meantime; without trimming all my plants away.
Due to the amount of algae in this tank, spot treatments aren't a feasible option. And it has proven to be resistant to whole-tank treatments. Two previous ones were somewhat noteworthy:
1) 4ml/G of H2O2, allowed to circulate through the filters with media removed for 30 minutes, followed by a 50% water change. Slows the algae down substantially if repeated multiple days in a row, but doesn't come close to wiping it out. Slight damage to Blyxa Japonica.
2) Metricide, equivalent to 5x Excel overdose, for one day only. Effectively killed the algae in the highest flow areas, with visible results after a day, but left other areas untouched. I'm hesitant to use this high an overdose for more than one day. 2-3x equivalent daily overdose has no effect.
Today, I intended to try a combo whole-tank treatment consisting of moderate doses of both H2O2 and Excel. Which I didn't really expect to work very well. But I messed up, with interesting results.
Before lights-on, I did an H2O2 treatment as above, but with only 2ml/G of H2O2. Then I dosed 4ml of Metricide, which is equivalent to a 1.7x overdose of Excel. There was no Metricide or H2O2 in this tank for a week prior.
By then, it was nearly time for lights-on; but the 50% water change had reduced CO2 levels. Instead of pushing back the lighting schedule, I temporarily cranked up the needle valve and CO2 flow through the Atomic inline diffuser.
Well, I overshot. I'm not sure how much. All I know is that by the time the lights came on, the tank looked like sparkling water. All the fish were gasping. And the pH test was yellow, with no hint of green. Oops! I cut off the solenoid until I started to see some green in the pH test.
Now for the interesting part. Just four hours after this, staghorn in the highest flow areas suddenly turned a brilliant shade of fuschia! Not even 5x Excel equivalent overdose did that. I'm not sure whether it was the excessive CO2, or some combination of that and the moderate H2O2/Excel. More experiments will be necessary to determine this.
And this is really interesting
This infested wisteria is directly underneath the outflow of my second filter, which is not where the CO2 comes out. The arrow on the right points to staghorn, which although it's out of focus (sorry), is now fuschia and definitely dead. The arrow on the left also points to staghorn, but it's not visibly affected. The only difference is the area on the left, even though it's swaying in the current, is shielded from direct flow by just a few wisteria leaves
Obviously, there's a lot in this that's open to interpretation. Feel free to do your own. But it does clearly demonstrate the dramatic effect of flow. I'd already put a Koralia clone on order last week for this tank, and am eagerly awaiting its arrival.