Mystery Water Parameters

Greetings,

When I originally set up my current 75g planted tank, the tap water
here was pH ~7.0 with a gH of ~2 and a kH of ~1.5.

Now, a year later, the water coming from the tap has a pH of 8.3!
Even though the hardeness levels have remained the same.
(And no, it's not the test kits...)

Aging the water doesn't help, and makes water changes a real PITA!
Am I going to have to resort to RO/DI water?

What on earth are they adding to the water that is causing this?
What could be in the water that it doesn't effect the hardness levels?
Also, water changes are causing algea blooms.

Thanks for any insight,
Greg

Greg G. wrote in message
...
...

...Now, a year later, the water coming from the tap has a pH of 8.3!

But your aquarium environment has matured and, depending on your setup, if
it's planted moderately-to-heavy, may be able to handle 25%+ weekly water
changes - test aggressively until you get the hang of it.

My tap water is over eight-degrees and I do weekly 1/3 water changes into my
75-gallon with no problem (3 wpg w/ 3 DYI CO2 bottles).

...Also, water changes are causing algea blooms.

City water? Test for phosphate. Not that there's much you can do about it,
other than to crank up the lighting, CO2, and trace mineral to attempt to
compensate.

Good luck.

"Greg G." wrote in message
...

Greetings,

When I originally set up my current 75g planted tank, the tap water
here was pH ~7.0 with a gH of ~2 and a kH of ~1.5.

Now, a year later, the water coming from the tap has a pH of 8.3!
Even though the hardeness levels have remained the same.
snip
What on earth are they adding to the water that is causing this?
snip

Caustic soda is what my municipality adds to bump the pH up.

NetMax

On Sat, 8 Nov 2003 16:18:23 -0500, "NetMax"
wrote:

snip
Now, a year later, the water coming from the tap has a pH of 8.3!
Even though the hardeness levels have remained the same.
snip
What on earth are they adding to the water that is causing this?
snip

Caustic soda is what my municipality adds to bump the pH up.

NetMax

Thanks, I had about given up on an answer-short of taking it to a lab.

Any ideas on counteracting this, short of R/O-DI or peat filtering?

Greg

"Greg G." wrote in message
...
On Sat, 8 Nov 2003 16:18:23 -0500, "NetMax"
wrote:

snip
Now, a year later, the water coming from the tap has a pH of 8.3!
Even though the hardeness levels have remained the same.
snip
What on earth are they adding to the water that is causing this?
snip

Caustic soda is what my municipality adds to bump the pH up.

NetMax

Thanks, I had about given up on an answer-short of taking it to a lab.

Any ideas on counteracting this, short of R/O-DI or peat filtering?

Greg

The first step IMO would be to ascertain exactly what your municipality
is doing. Contact them and they will FAX you the water parameters and
some history. The addition of caustic soda is to reduce the decay of
their pipes. It might be transitional while maintenance or
infrastructure work is underway, or they might be about to change to a
different method. Make your plans from accurate information.

AFAIK, caustic soda has no effect on gH or kH, only pH, and it's not
particularly stable. In my situation (7.6pH, 2-3dgH, 1-2dkH), it's easy
to drop the pH with CO2 injection as the kH is so low, however there is
some danger of a pH crash (even without CO2). Our municipality's water
leaves the treatment plant at 9.1pH, but 7.6-7.7pH is what I typically
get out of the tap. Time of day, and day of week may also influence your
pH. Standing water pH will be much lower, so Sunday night's water
should be much more acidic than Monday afternoon.

I've just started to add a bag of crushed coral to a filter compartment
to see if I can boost the kH slightly while keeping the pH in the low 7s/
high 6s. It's an experiment to see if I can achieve some greater
stability through non-chemical means. My test application is a high
fish-load, 1/3 planted, non-CO2 tank running 50% w/c per week (almost
continuous w/c system). If anyone has any other ideas on how to
counteract caustic soda without stripping my last few remaining
carbonates, I'm all ears.

NetMax

"NetMax" wrote in message .. .
[snip]
AFAIK, caustic soda has no effect on gH or kH, only pH, and it's not
particularly stable.
[snip]

Caustic soda is NaOH. While it doesn't directly affect kH, it will
indirectly raise it.

Once the water is out of the tank, the concentration of CO2 will come
to some equilibrium. If your pH is high due to NaOH addition, some of
the CO2 the water absorbs will be converted to bicarbonate. The water
will keep absorbing CO2 until the kH is at the equilibrium level for
the pH and CO2 concentration. During this process the pH may come down
a little.

In other words, at a given CO2 concentration and pH level, there's
only one stable amount of bicarbonate. So, given a little time, your
water will get there.

I've just started to add a bag of crushed coral to a filter compartment
to see if I can boost the kH slightly while keeping the pH in the low 7s/
high 6s. It's an experiment to see if I can achieve some greater
stability through non-chemical means. My test application is a high
fish-load, 1/3 planted, non-CO2 tank running 50% w/c per week (almost
continuous w/c system). If anyone has any other ideas on how to
counteract caustic soda without stripping my last few remaining
carbonates, I'm all ears.

For the reasons I just explained, you can't. Adding CO2 is the only
possible mechanism to reduce pH without reducing kH. This is because
the pH is set by the ratio of CO2 to bicarbonate. So if you reduce pH
without adding CO2, you'll reduce kH. If you increase pH without
adding bicarbonates, you'll quickly get more bicarbonates anyway as
atmospheric CO2 gets converted.

- Jim

"Jim Seidman" wrote in message
om...
"NetMax" wrote in message
.. .
[snip]
AFAIK, caustic soda has no effect on gH or kH, only pH, and it's not
particularly stable.
[snip]

Caustic soda is NaOH. While it doesn't directly affect kH, it will
indirectly raise it.

Once the water is out of the tank, the concentration of CO2 will come
to some equilibrium. If your pH is high due to NaOH addition, some of
the CO2 the water absorbs will be converted to bicarbonate. The water
will keep absorbing CO2 until the kH is at the equilibrium level for
the pH and CO2 concentration. During this process the pH may come down
a little.

In other words, at a given CO2 concentration and pH level, there's
only one stable amount of bicarbonate. So, given a little time, your
water will get there.

I've just started to add a bag of crushed coral to a filter
compartment
to see if I can boost the kH slightly while keeping the pH in the low
7s/
high 6s. It's an experiment to see if I can achieve some greater
stability through non-chemical means. My test application is a high
fish-load, 1/3 planted, non-CO2 tank running 50% w/c per week (almost
continuous w/c system). If anyone has any other ideas on how to
counteract caustic soda without stripping my last few remaining
carbonates, I'm all ears.

For the reasons I just explained, you can't. Adding CO2 is the only
possible mechanism to reduce pH without reducing kH. This is because
the pH is set by the ratio of CO2 to bicarbonate. So if you reduce pH
without adding CO2, you'll reduce kH. If you increase pH without
adding bicarbonates, you'll quickly get more bicarbonates anyway as
atmospheric CO2 gets converted.

- Jim

In my case, the NaOH added by the municipality brings the 3dgH, 1dkH
water from the low 6s (during treatment) to the low 9s. Water leaves the
treatment plant at 9.1pH and arrives at our tap at about 7.6pH (I
attribute the pH drop to the iron leeching en route). There seems to be
no apparent difference to the kH, so I surmise the CO2 concentration is
already in the 3-4ppm range. Without doing anything, this water used for
aquariums will easily pH crash, so the addition of crushed coral is to
maintain a minimal amount of kH in the water. If this settles at 6.8pH
or 7.6pH or anywhere in between, I'll be satisfied, as stability is my
objective. In my Discus and Cardinal tanks, I _do_ use CO2 injection to
drop the pH to the 6.5-6.8pH range (also some Mopani). Surprisingly,
these tanks seem more pH stable (this might just be my imagination... too
many tanks running ;o).

NetMax