Danios: Behaviour and appearance questions

Mean_Chlorine wrote:
Thusly FishNoob Spake Unto All:


PH is between 5.0 and 6.0 (bit closer to 6), ammonia is 0 and nitrite

is 0.1.

That's a low pH. Unless you are breeding sof****er fish like neons,
you'd have greater margin of safety if you put a couple of limestones
in the tank (which'll buffer the water and give a pH of 7.5).

So it's okay to put some limestone in? I read some websites that said
that rocks were okay to add as long as they *weren't* limestone


Yeah, that's because most websites don't know anything at all about
water chemistry, and simply quote eachother and/or books by authors
who don't know anything about water chemistry either, therby
perpetuating a whole range of myths.
Limestone in water will neutralize acid, and raise pH. Most of our
fishes come from water with a pH of about 6 - 8. This much everyone
know. What the websites etc miss is that the dissolution of calcium
carbonate has an endpoint at 8.3 (which, incidentally, is a 100% safe
pH), and that the process speed decreases the closer you get to 8.3,
so the actual pH in an aquarium filled with limestone will stabilize
around 7.5. That is, you _can not_ kill your fish by raising pH with
limestone. You will never reach dangerously high pH's. Ever.

You've got me curious because I've not seen pH stabilize around 7.5 when
I fill a tank calcium carbonate. I've always had hard, high pH
tapwater, though. When I stuff a tank with carbonates, it's usually for
marine fish or Tanganyikan cichlids and with hard water to start with,
the pH generally ends up above 8.0. If you have time to elaborate on
the equilibrium chemistry for soft water or have a link, I'd enjoy
taking a look.

--
Elaine T __
http://eethomp.com/fish.html '__
rec.aquaria.* FAQ http://faq.thekrib.com