"Iain Miller" wrote in message
...

"xtr396472" wrote in message
...
I have started to use Flourish Excel to feed my plants instead of DIY
yeast
CO2
The only problem is my tap water KH is 3 and pH at least 7.6
What is more important to maintain the pH or the KH. I would like to
get
the
pH down to around 7 with out using CO2 just for breeding purposes.
Any thought apprec.
Thanks

The two are linked. At a known level of CO2 (i.e. what you get from the
Atmosphere) as KH falls so Ph will fall with it. In other words if you
want
to bring down the Ph to 7 then you need to reduce the Kh which you can
do
with Peat, or bogwood etc.

Does the kH drop significantly with CO2 injection? My understanding was
that the pH dropped with CO2 injection because the kH didn't. On the
other hand, CO2 makes carbonic acid which would drop your kH.

However, two issues...

a) As Kh approaches zero so Ph becomes unstable and can crash (to 5 &
below)
with disasterous results.

b) At levels below Kh 3-4 you get Ammonium instead of Ammonia released.
This
means your Bio filter dies back a bit. If you then bring the Kh back up
to 4
& above for any reason the Ammonia suddenly gets released as Ammonia
with
similarly diasterous consequences - this one is known as "Old Tank
Syndrome"
since over time the Kh of a tank will naturally fall (unless there is
anything in the tank to hold it up). With a tank like that if you then
do a
water change and so restore the Kh everything can go a bit pear shaped.

I thought the NH4 to NH3 conversion was a direct function of only pH.
Under acidic forces, the kH will indirectly alter the NH3 to NH4 by
allowing the pH to drop (but I'm no chemist).
--
www.NetMax.tk

Safest way to bring Ph down to 7 & below is with CO2.

rgds

I.