You can put the dolomitic lime in your filter instead of the sock. but it seems it
has done the job of adding a buffer. Baking soda may increase the pH quickly (not
desirable), but it wont provide lasting stability cause the bicarb breaks down to CO2
and leaves the pond. That is where the dolomitic limestone comes in. It slowly
releases on demand as needed, almost like having limestone in the pond. anything
above 50 is OK, altho higher is better.
It is expected that pH is low in morning as the CO2 has been removed during the night
by plants in the water. During the day CO2 and O2 levels increase with pH peaking
right before sunset. But the more plants (algae) in the water, the larger the swing
.... do you have green water? It could be if your water is green and warm then the
plants are using up the oxygen... especially if you dont have sufficient oxygenation.


So maybe other people could share what their morning and late afternoon pH is? I did
a search to find out what "normal" swings are but I think this group could provide
the data. Please include pH out of the tap and if you have noticed pH shifts after
heavy rains.

Ingrid



"JGW" wrote in message
I have a "Master Test Kit" On 5/2/04, when I found the first fish
dead, the pH was 8.2 (late afternoon). The KH was 53.7 ppm and the GH
was 71.6 ppm. Several days later, I tested the pH first thing in the
morning and it was around 7.0. That was when I added the dolomite
lime.
Today, when I found the second fish, the pH was between 6.8 and 7.0
(around noon). The kH was 71.6 ppm and the GH was 107.4 ppm.
I am thinking I may be having too large pH swings and that the water
hardness is too low. I have the dolomite hanging in the water in a
leg from a pair of panty hose, and periodically I squish it around to
try to release more into the water. It hangs right below the
waterfall.

Your numbers...

KH 53.7 to 71.6
GH 71.6 to 107.4
pH 8.2 to 6.8/7.0



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