Re: KH/pH/CO2...

> Non-carbonate buffers will give you false "KH" readings since most "KH
> test kits are measuring total alkalinity.  If you use a table to
> determine CO2 levels from pH and KH, the readings will be off.  If you
> use a CO2 test kit, you should have reliable readings as long as there
> are no strong mineral acids present.
Accurate CO2 measurement was one thing I was concerned about with the
presence of non-carbonate buffers.  It still hasn't become clear to me
what the difference is between KH and "total alkalinity".  I think at
this point I'd rather remain unclear. :)
> Use sodium bicarb to get 2 dKH.  Inject CO2 to bring your pH down to
> 6.6.  You will have 15 ppm of CO2.  Since you have a pH controller,
> you don't need as much buffering.  With regular water changes
> (refreshing any loss of KH due to nitrification), you won't have a
> problem with pH dropping.
> Are you sure you really need to keep your discus at pH 6.6?  Many
> successful discus keepers and breeders use whatever their tap water
> gives them.  You may be causing more problems messing with the water
> chemistry (and having it vary accidentally) than they would experience
> if they acclimated to a higher pH. Ours are very happy at pH 6.9.
No, I'm not at all sure I need or want to keep the Greens at pH 6.6.  In
fact since my pH rise, the other day, I have kept the pH at 6.9.  I
figure I'm probably wasting CO2 trying to keep the pH so low at my KH
anyway.  I've also allowed the tempurature to gradually drop to 82F from
86F.  I've noticed some plants are no longer thriving like they were
before I raised the tank temperature.  In addition, I noticed in Amano's
book that he keeps his Heckel's in 81F water with a pH 6.8.  I see no
reason why I can't do the same.  Greens are certainly less sensitive
than Heckels.
Mike from St. Louis
vandi at well_com