kh weirdness

Robin wrote:
Hi!

This is a request for help. [***]

I have [a 5gal, with DIY, eco-complete and no livestock].

After a day or so of CO2 injection I tested the water. Strangely, my
kh went up from 4.5 tap water level to 7. The Ph went up too, from
7.6-7.8 tap water level to 8.0. Huh? So, I increased the
yeast:sugar
ratio today and the Ph has fallen to tap water level but the kh went
up
9. I measured it twice and then checked the tap water level again to
make sure the test itself wasn't faulty.

I scooped out some substrate and tried the vinegar test and no fizz.

What you didn't report, however, was what would happen to the apparent
KH and pH of your 5-gal tank *without* the DIY yeast going. So, off
the top of my head, here are some experiments you can do:

(1)
Do a near-total (or total) water change, and discontinue DIY CO2.
Also, keep some new tapwater in a clean glass container open to the
atmosphere. Over the course of a day or two, perform KH and pH
analyses of the tapwater stored in the clean glass container, and the
water in the tank.

You should expect to see some excursion in the pH in the first day or
so, as the waters outgas and equilibrate CO2 with the air. After
sitting for 24 hrs (and probably less, since it's only a 5g tank) there
should be no further pH excursions in the aquarium unless you have
something going on in the substrate (decomposing mulm, or sneaky
carbonates, etc.)

If, after a couple days, you have observed a stabilization of KH and
pH, then you may have some cause to suspect something screwy with the
DIY CO2 was tweaking your water.

If, after a couple days, you have NOT observed a stabilization of KH
and pH, then you may have some cause to suspect *both* the substrate
and your DIY CO2.

(2)
Get 2 clean glass containers, fill each with tapwater before bedtime.
Next morning, wake up and take KH and pH readings on each. Then
connect your DIY CO2 to one container. Go to work, have a life for a
day, etc. Next, test KH and pH of both containers' water.

If your DIY CO2 has been working correctly, the KH of both containers'
water should be the same. The pH of the CO2-injected water should, of
course, have lowered.

If the KH of the CO2-injected water *has* changed, then the only think
I can think that means is that some of the yeast soup from the
fermenter is getting into the water and mucking things up.

(3)
This is more of a research type experiment. Go to google, and try to
find a recent analysis of your tapwater source. If you live somewhere
civilized, i.e. a city or something like it, the water utility's
analysis is almost sure to be findable. If you're on a well, you may
have a tougher time with this. I think you'll be most interested in
the carbonate hardness (which you'll likely get in equivalent ppm of
CO3--) but it could be of interest if you have a big phosphate spike in
there, too.


The only other factor is ammonia. I'm trying the fishless cycling
method and it's currently 5.0 and nitrites appeared today at .25. I
don't think this is relavent, though.

I think we can safely neglect ammonia for this, yes.

I have no idea what I'm doing wrong. I searched the forums and the
only other mention of a kh rise w/ Co2 involved a tablet (I'm using
yeast). Can anyone help me?


Here's yet more info. Case study: my tanks and tapwater. I live in
NYC, and the tapwater has a KH of 1. Though I'm running a large tank
with few fish and it would be safe to keep a KH that low, I nonetheless
do not, and up it to somewhere between 3-4 with baking soda. I run
pressurized CO2 and a pH controller to keep the whole pH/KH/CO2
equation where I want it.

In my opinion, once you have an understanding of the KH/pH/CO2
relationship, getting and using a pH controller and pressurised CO2 is
the single easiest and most brainless way to get your water to any
desired pH while maintaining the CO2 concentration plants like.

HTH,
Trapper

Thanks for all of your suggestions.

The tank had been set up previously so I am fairly confident about the
behavior my non-co2 water values. (The little minnows I kept sadly
were infected w/ tb and died off. I took the tank apart and gave
everything a good bleach soaking/scrubbing followed by lots of rinsing
and decholorinating, a new filter pad and bio-wheel, and new gravel.)
The ph is 7.0 out of the tap, 7.5ish after standing (CO2 dissolves),
and used to fluctuate from 7.8 to 8.2 with the presence of a plant.
The kh had always been stable at 4.5.

So, you're right, something is either screwy with the gravel or the diy
CO2. I removed the CO2 for now and changed the water in the tank, and
am going to observe the kh/ph with just the gravel. I think I'll also
try the CO2 container test you mentioned. Hopefully I'll get some
clues!

I'm occasionally in NYC and enjoy the famously soft water. ((My
friends tell me it's the secret to those delicious bagels.)

I think I solved the mystery.

The gravel + water on its own yielded no rise in kh, and neither did
the CO2 into a bottle. But, when I was running the CO2 into the tank I
used a check valve. (I didn't use the valve when I ran the CO2 into
the bottle.)

Well, the check valve had some type of filtering material. It was the
only valve in the fish store and I didn't think much about it when I
bought it. I found another valve w/ no filter material and tried
injecting the CO2 into the tank again, and, no extra kh.

I feel silly because I hadn't noticed this before posting!

Robin wrote:
I think I solved the mystery.

The gravel + water on its own yielded no rise in kh, and neither did
the CO2 into a bottle. But, when I was running the CO2 into the tank
I
used a check valve. (I didn't use the valve when I ran the CO2 into
the bottle.)

Well, the check valve had some type of filtering material. It was
the
only valve in the fish store and I didn't think much about it when I
bought it. I found another valve w/ no filter material and tried
injecting the CO2 into the tank again, and, no extra kh.

I feel silly because I hadn't noticed this before posting!

Hey, I'm glad you found the culprit. Now, on to the real business of
fish and plants!

Contact me off-line if you want a copy of my ph/kh/co2 chart. It
prints nicely and is good to keep taped up near your tank.

montagnard_army at free-email-provider-beginning-with-y dot see-oh-em.

--
Trapper