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CO2 vs. KH testing

Ok, first off a disclaimer…I am not a scientist or a chemist so my test may
be flawed.  With that said here is what I did layman style :o)

Reason for test:
I wanted to see if I could increase the PH levels by increasing the KH.
Also to see if I could lower the KH levels by lowering the PH by way of CO2.

I am using a CO2 canister and needle valve not DIY CO2.  I have a bubble
counter and a DIY Diffuser.   The Diffuser is not efficient due to the fact
that there are still tiny bubbles coming out of the bottom indicating that
the CO2 is still not mixing to maximum capacity.

Lighting is one VHO T-12 110 watt light and one 40 plant light from GE.
They are on for 12 hours per day.

Tank size is 55 gallon regular.

Plants are heavily planted.

Filters are one bio real on slow setting and one power head pushing water
through the diffuser.

Water changes every week about 45% or 20 gallons.

10-25-01 5:30pm

I wanted to do a water change before conducting the test.  I checked the
water before water change and here are the results.

CA     		23
MG      		8
FE     	 	7.5
GH      	 	5
KH      		3
PH      		7
CO2   		10
PO4   		Above 2
NO3 			12.5

After water change
KH 		2
PH 		7

1 hour after adding 2 tspn baking soda
KH 		4
PH		7

2 hours after adding another 2 tspn baking soda
KH		6
PH		8

Notice the rise in PH?  Lights had been off for an hour by then so can that
account for the rise in PH?  BTW, I had not added any plant food or anything
else at this point.

10-26-01 9:00 am

Checked water in the morning

KH		7
PH		8

Lights have been on for 2 hours now.  PH is still high did the baking soda
make this go up or has the PH just not gone down from being off for the
night?  Thought the PH swing would be minor.  This is not minor to me.

1 hour after adding 40ml of flourish and 20ml TMG

KH 		7
PH		7.5 - 8

1 hour after adding 1 tspn K2SO4.  Some one told me that by adding plant
foods it may mess up the PH and KH readings.  This is why I am going step by
step here.  Plant food is all in now.  I did not add Fe or KNO3 or PO4 at
this time.  They seem fine for now.  BTW, I do not have a test kit for the P
so I am just going on how the plants look.

KH		7
PH		7.5

I hour after doubling my bps CO2.  Started with 2 bps now up to 4 bps.

KH		7
PH		7 – 7.5

2.5 hours after doubling the bps CO2 to 4bps

KH		7
PH		7

4 hours after doubling the bps CO2 to 4bps

KH		7
PH		6.5 to 7

10-27-01 5:00 pm

Just checked once more and found….

KH		7
PH		almost a strong 6.5

So I have now proved to myself that the KH is in no way directly affected by
the swing in PH when the CO2 is altered and that the PH is in no way
directly affected by the swing in KH when the KH is altered.  Which brings
me to two more questions...how high is to high for the KH?  And should I
bring the GH up also?

Dave Berryman