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Re: CO2 Comments

Julius Odian wrote:

>1) Someone mentioned that the CO2 dropped the PH to a level that made
>their fish happy. This is not a safe practice. If you have a power
>outage and your solenoid valve shuts off, the PH can rapidly jump
>putting stress on the fish. It's a bad idea to regulate PH with CO2.
>If you need to lower your PH, use RO water and then use a buffer to
>maintain a certain level.


That was me!  Glad you clarified this.  A manual system wouldn't be affected
by a power failure, but RO water sounds like a better idea.  What was
happening in my tank was a little different - in my case a massive
infestation of hair algae was driving up the PH.

My water comes out of the tap at about 7.4.  I have had a hair algae problem
in my tank since I moved to this house (was fine in the old house - very
different water).  All of my attempts to erradicate the algae failed
miserably (and there were many approaches that I tried).  Recently, the hair
algae was growing so well it would almost fill the 50 gal tank every week or
so.  I would harvest it on the weekend and it would be right back.  One of
the side effects of this was that the algae seemed to drive the PH up - over
8.5, close to 9.  Water changes and chemicals failed to keep the PH
reasonable for very long.  After about a day or so it would be right back up
there.  (I didn't have CO2 on the tank while this was going on. )

A month or so ago I finally broke down and put a CO2 cannister on the tank.
This kept the PH in the 7.2-7.4 range - cardinal tetras much happier!  Then
a couple of weeks ago I decided to completely cover the surface of the water
with water lettuce (as suggested by Diana Walstaad in her book).  This of
course shaded the algae, but it also caused the PH to stay in the 6.6-7.0
range.  Perhaps the water lettuce also released allelochemicals toxic to the
hair algae (as suggested in the book).

In any case, the hair algae stopped growing!!!!!  It wasn't disappearing,
but it wasn't growing either.  The problem - neither were the plants.  Since
the plants were starting to decline I felt I had to remove the water
lettuce.  I decided to adjust the CO2 to keep the PH under 7.0.  After
another week the hair algae was completely gone!!!!  Plants are doing well
now.  Fish are fine.  Algae has been gone for a couple of weeks.  I think it
may be gone for good.

My friends and family have laughed at my futile attempts to kill hair algae
over the past 2 years.  They giggled over the 2 liter coke bottles of algae
all over the deck - various experiments.  Finally, the algae is gone.  You
know what?  I'm almost disappointed.  It has been so much fun reading this
list and going through the APD archives to figure out what the !@#$% was
going on!

I may put the PH back up to 7.2-7.4 just to see if the algae comes back, but
I think I'll just sit for awhile and enjoy my new CO2 system and a tank free
of hair algae for awhile.  And I didn't even have to get any Florida...err
American Flag Fish!!!  ;)

Anna