- algae and phosphates
by Thomas Narten <narten-at-cs.duke.edu> (Fri, 13 Jan 1995)
by Thomas Narten <narten-at-cs.duke.edu>
Date: Fri, 13 Jan 1995
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From: huntley-at-ix.netcom.com (WRIGHT HUNTLEY)
Subject: Algae in the aquaria FAQs
I corresponded quite a bit with Pat White about my problems, outlined
in the unpublished note below.
He pointed out that the same guy at the store that sells pH-DOWN will
then happily sell you a couple of algae eating fish, then some pH-PLUS,
which is sodium mono-hydrogen phosphate.
Pat thought this topic needed better coverage in the FAQs, so how about
we volunteer him to do it? (Based on the "every good deed receives its
just punishment" theory). He has gone way out of his way to help me, so
I would volunteer to put it together, rather than trouble him. If you
read thru the long note below, you will see why I think I lack the
expertise to do the subject justice.
****Start of unpublished note****
You, Too, Can Grow Lush Algae
It's really easy to mess up your tank(s)
It all got going when I almost started a flame war, because I had never
seen the (ancient?) data that were the basis for a lot of work on
substrate heaters for plant growth. I had been indoctrinated in the old
school, where ugfs were "good" for your plants, and you only changed
water because you didn't know how to balance a tank (replacing the
water used to vacuum the sand did not count). Recently reentering the
hobby after many years of "tanklessness," I was frustrated at the poor
plant performance in my four small tanks. The plants were really puny,
and a lot of them were much worse -- you know, .....dead or dying.
Communication with several of people on the *.aquaria groups got me
infected with the underwater gardening bug, and I quickly zeroed in on
the inadequate lights that came in the hoods, and the (even worse)
flourescents I had used to replace them. Meanwhile, I was tinkering with
the water, and lengthening the timer schedule on the lights (on at 6 AM
and off at 9 PM).
New tri-phosphor lights and the longer hours had caused an explosion in
plant growth by the middle of last month. A lot of algae was showing up,
but I left for Christmas thinking things were really OK.
Six days later I came back to a visual disaster. Of four tanks (2-20G
and 2-10G), not one was in decent shape. The water in the neons' tank
was clear, but the bottom and sides were solid with thick hair or beard
The big guppy tank was so green and cloudy that you couldn't see half
way to the back. Many of the plants were dying and rotted leaves were
all over the bottom. The small guppy tank was so overgrown with
hygrophila and corkscrew val that the fish had no swimming space. This
tank had hair algae well started, and the beautiful pale tan volcanic
rocks were solidly coated with nearly black algae. The larger community
tank was in the best shape, but it, too, was full of algae, with a thick
slimy green coating on most of the glass.
Water changes, boosted filtration, scraping and general cleanup got
things moving in a better direction, but the algae was here to stay and
showed every sign of outgrowing the plants. As I was tinkering with a
DIY CO2 setup, I decided to monitor the pH of the tank I was working
on, to see if I was getting any increase in dissolved CO2. The pH was an
astonishing 6.8! Our normal water here is about 7.4, and I knew the tank
was much too buffered with calcium carbonate to push the pH that far
with a stream of CO2 bubbles.
Then, it hit me. About six weeks ago, I was tinkering with the water,
and added some pH-DOWN to push the tanks closer to neutral pH.
Making a mad rush to find the bottle, I finally bothered to really read
the ingredients. It turned out to be pure sodium di-hydrogen PHOSPHATE!
Detergents with phosphates are outlawed in many areas because they
cause so much algae bloom in the water, even after sewage treatment.
[according to Pat, phosphates are the limiting nutrients for most algae]
Here is the recipe for really healthy algae, folks. Start with 15 hours
a day of strong (>2 W/G) tri-phosphor flourescents. Let nitrates get way
up around 100 mg/L and above. Add some phosphates and wait a few
weeks. I guarantee nice green surfaces. To get the super-green water and
dead plants in the big guppy tank, it helps to buy a cheap heater whose
thermostat sticks and (once in a great while) cycles the temperature to
up around 100F (38C) before unsticking and resuming regulating again.
Maybe, for my next posting, I will do a piece on raising trash fish for
fun and profit. It's been over thirty years since I raised any african
cichlids, so I think I have forgotten all the bad parts.
****end of unposted note****
Please feel free to use any or all of this stuff, but remember that I am
quoting Pat from memory, so don't hold him too responsible for my
attributions to him.
"The first (and key) step to liberty is to be a good neighbor."
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