NetMax wrote:
"Elaine T" wrote in message
om...

As for substrate, if you have a substrate that doesn't affect pH, and
you change to a second substrate that doesn't affect pH, there will be
minimal impact. If your stubstrate is very dirty and leaching organics
into the tank, the pH may rise some. This is a good thing if your
substrate was that dirty and not planted!

Examples of pH neutral substrates are coated aquarium gravel, glass or
plastic marbles or decorating pebbles, rock or sand that doesn't fizz
when tested with acid, Fluorite, Eco Complete, and Onyx. Most lava
rock, tuffa, obsidian, sandstone, slate, shale, and clay does not
change pH. For acid testing, Oz says vinegar is not strong enough but
pH Down does the trick nicely.

Examples of pH changers are aragonite, crushed coral, substrates
designed for African rift lake cichlids, and rocks or sand that DO fizz
when tested with acid. pH changing rocks that come to mind are
limestone, marble, and some granites. I'm sure there are more.

Out of curiosity, why are you changing your substrate? Plants are
pretty flexible as to what they need to grow and you may be fine with
just laterite tablets under root feeding plants like Crypts, swords,
and Aponogetons.

--
__ Elaine T __
__' http://eethomp.com/fish.html '__



I had a geologist explain that there is sometimes some unpredictability
in how rocks react, as they are composed of various minerals.
Fortunately, it's in the minority of cases so your description holds
true, but I do have some red feldspar sandstone which seems to level off
at 7.4pH. It hardens sof****er, but not hardwater. Just fyi for
interest ).

I haven't run across a pH changing sandstone before - sounds like an
attractive mineral. That is why I said most with the minerals. I've
run across both pH changing and non-changing granites, and had what I
thought was marble not change my tank pH.

--
__ Elaine T __
__' http://eethomp.com/fish.html '__