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post #1 of 5 (permalink) Old 12-29-2005, 02:28 PM Thread Starter
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More water chemistry questions

I have 2 tanks, a 30g and a 55g.
I recently began running pressurized CO2 on my 55g.
I run DIY on the 30g.
I dose both EI with GW ferts, with 50% water changes weekly.

I'm wondering about elevated Kh readings in my 55, which suggest way-high CO2.
Just took these readings this a.m.
55g kh: 8.5
30g kh: 7.0
tap kh (fresh): 6.0

I'll let a tap sample stand and retest tomorrow.
In the past, my tap and 55g kh were around 7-7.5.

My pressurized CO2 is running 24/7 around 80 bpm. This morning the Ph in my 55 was 6.4.

I had recently upped the CO2, trying to discourage some BBA, but didn't realize it had gotten this high. This a.m., before the lights went on, the kh and ph yield a CO2 ppm of 80-100.

This sounds REALLY high to me. But I don't see any fish gasping or other signs of stress.

Any thoughts? Should I decrease my CO2 bpm?
Why would the kh in my 55 be so much higher than the 30 or tap?
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post #2 of 5 (permalink) Old 12-29-2005, 02:34 PM
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CO2 injection doesn't raise Kh...if anything, it will reduce Kh over time if you don't do regular water changes.

Substrate choice, and water changing habits strike me as possible reasons for different Kh in your tanks. Did you retest Kh to rule out a bad testing? I know my Kh reagent bottle sometimes likes to drop smaller droplets.

80bpm is pretty high. I have almost 10 dKh, and I only run about 45bpm on a 75gallon.

High CO2 doesn't mean low O2...this is why your fish won't gasp just because CO2 is over 60ppm.
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post #3 of 5 (permalink) Old 12-29-2005, 02:57 PM Thread Starter
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I change both tanks 50% on the same day.
I wasn't trying to suggest that the CO2 elevated the Kh - only that I calculate CO2 ppm via Kh and Ph, and the combination of lowered Ph and elevated Kh add up to very high CO2 levels.
The 55 is probably 80:20 flourite:gravel, the 30 is an approx 50:50 gravel:flourite, with some laterite.
(The 30 was originally gravel with laterite. When I set up the 55 maybe 4 months ago, I used some old gravel from the established 30 to get the 55 going, and added flourite to replace what I had removed.)

The Kh and Ph readings have been pretty consistent over multiple tests over the past couple of weeks, and the Kh test is only a month or 2 old. It seems as tho the tank's Kh readings increased right about when I started EI dosing with GW products. Any possible link?
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post #4 of 5 (permalink) Old 12-30-2005, 03:42 PM Thread Starter
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Just did the post 24-hr test on my tap H2O.
Kh 6.5-7
Ph 7.2

Retested the H2O in my 55 gal
Kh 8-8.5
Yesterday's reading was 8.5.

So it seems as tho something in my 55 is elevating the Kh.
Any thoughts?

I recently pulled the wood from my 55.
Was having recurrent algae problems, despite repeated bleachings and soaking.
It was a stump I pulled from a lake, but I fear it was soft wood - most likely white pine.
It never would sink, and after 3-4 weeks it would get covered with various slimey algae.
Replaced it with several rocks that I thought were inert.

The Kh was reading elevated around 8 prior to exchanging the wood for the rocks.

Is this Kh or CO2 ppm something I should be concerned about?
Should I scale down my CO2 bpm?

The fish seem healthy.
Plants are showing good growth, tho I'm still getting some black algae growth on the lower leaves of several plants, and fuzzy black growth on individual pieces of flourite, but it seems somewhat less than before.
I did a major replanting 3 weeks ago, and am hoping that as the plants come more "on-line" they'll outcompete the algae.
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post #5 of 5 (permalink) Old 12-31-2005, 12:46 AM
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Get a better pH test kit. Water with a kH of 6.5-7 will have a pH of 7.8
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