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Re: Aquatic Plants Digest V2 #1100
Pat Bowerman wrote:
> > Green water blooms were related to iron fertilization. I stopped using
> > it and the green water disappeared quickly. I let the tank stabilize and
> > afterwords I was able to gradually worked the fertilizer back up to a
> > useful level.
> This makes sense. Roger, how did you "let the tank stabilize" ?
> Pat Bowerman
I had been using short light cycles and weekly 50% water changes to try to
clear the green water. Those tactics and can't be maintained for long
periods - they aren't stable methods. Those tactics worked twice for
short periods, then the green water returned. So I put the tank on a
12-hour on, 12 hour off light cycle, stopped fertilizing entirely (I was
fertilizing weekly at each water change, using the manufacturer's
recommended dose of a potassium+chelated iron fertilizer) and reduced my
water changes back to about 10% per week. The green water started clearing
a few days after the first skipped fertilization and was gone in about a
week. I kept that procedure for 3 weeks. That is what I called
"stabilizing" the tank.
After three weeks I restarted fertilizing at about 1/3 of the recommended
dose, and after a couple more weeks I increased the level to about 2/3 of
the recommended dose, which I held for a few months. I later switched out
a few slow-growing plants for faster-growing plants and now I'm
fertilizing at a higher rate than I did before the green water problem
That process worked for one tank after a big increase in lighting, and in
a second tank where I intentionally promoted algae growth in a plan to
beat back a long-standing bluegreen algae problem. One of my kids' tanks
also got green water after a lighting change and we just left that one
entirely alone. The problem disappeared after 2 or 3 weeks. I also have
seasonal (winter) green-water blooms in two sunlit, unfiltered,
unfertilized tanks. That problem should be popping up any time now.
Keeping those tanks clear without reducing the sunlight (which I love) is