Re:Possible substrate problem
>My fish and plants don't seem to mind being at 7.5 (they're used to
>it by now). It's easy to keep hard-water cichlids in Austin
>tapwater, but I'd like to evolve my tank into a community river tank.
>My concern is that I won't be able to introduce new fish and more
>difficult plants. I was trying to lower the pH with CO2, but at the
>current KH, there's no way to get to pH 6.9 without making Fish-Cola.
First, I want to congratulate you for reading the Krib and the
archives BEFORE you posted a question here. I am extremely weary of
people posting their problems here, when the question has already been
answered. Thank you.
Austin water comes from the Colorado River, which has a hardness of
120 ppm CaCO3 and pH 7.5. Sound familiar? It's no wonder your
aquarium will equilibrate to 7.5. It's not your substrate; there is
no need to tear down your tank. BTW, you already have a community
Of course your fish and plants don't mind a pH of 7.5--there is
absolutely nothing wrong with 7.5! You mentioned your plants were
doing great. Haven't you noticed the lush growth of native aquatic
plants in the Colorado River and Barton Creek? I suspect you have
been listening to some of the aquarium shops here--they love to sell
unnecessary water conditioners (even phosphate-based pH adjusters!)
and often over-exaggerate the hardness of the water here. They know
not. Ignore them.
I keep a 30 gallon plastic trash can full of tap water. I aerate it
for 48 hours, and voila! The chlorine is gone, pH is stable, and no
additives were necessary. I draw all my changing water from here.
From my experience, you have several choices. You can leave you tank
as-is, and do quite well. The aquarium shops here also use Austin
water, so the fish you buy will already be acclimated. Plus, these
fish come from a wholesaler in San Antonio, which has very similar
water. Vallisneria, Ludwigia, Hygrophila and Hornwort do very well
here. The San Marcos River is a great place to collect these plants.
However, if you want to grow Amazon swords or Apons or anything that
is moderately difficult, you will need to consider some kind of
substrate additive (laterite, loamy topsoil, etc). Since you have
already read the Krib, you know what I am talking about. I use 4" of
loamy topsoil/vermiculite overlain with 1" of sandblasting gravel. I
got the topsoil from Wolfe Nursery--40# for $0.99.
You will also need to add CO2--10-15 ppm CO2 will result in a pH of
about 6.8. This equates to about 2 bubbles/second from a CO2
generator. I use a 20# tank with a regulator and needle valve,
You will also need to add fertilizer-I use PMDD, and it works great.
I regularly sell my excess plants back to the aquarium shops; you may
have purchased some of mine!
In summary, you don't have a problem. You can leave your tank as is
and to very well, or you can make some modifications and do
exceedingly well. Whatever you do, don't listen to any of the
aquarium shops! The APD and Krib is your best source for good advice.