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Old 20-04-2003, 06:12 AM
kush
 
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Default Water Chemistry for Art Majors?

It's been quite a few years since that chemistry class I never took, so if
someone could give me a hand here, I'd be grateful.

I've got a 75-gallon standard tank with 110 watts of lighting. The tank has
lots of wood in it and is moderately to heavily planted and I'm injecting
CO2 through a powerhead and also with a diffuser next to the filter output.
I have a pretty heavy fish load for a planted tank, but my maintenance is
impeccable (imho).

Forty-eight hours after it's weekly 20% water change and adding double the
recommended dosage of trace iron, my stats a

Ph.............7.4-7.5
Nitrate.......not measurable
Nitrite........ 0.5 ppm
Gh.............3
Kh............. 12
Fe............. not measurable

I say the carbonate hardness is not measurable because after 12 drops it
just turns the same colour as the test liquid.

My water comes from a well which feeds into a water softener in the
basement. There is no practical way to bypass the water softener.

My specific concern is algae, and I've got a small, tolerable amount every
kind I've ever heard of and then some. The plants are all doing "OK" but
I'm afraid that things might be starting to slip away from me, despite two
2" plecos, a dozen ottocats and a host of snails of every race, creed and
colour.

Paradoxically (perhaps), the Red-spot Ozelot and the Hygro Corymbosa are
vividly red and thriving, so I'm thinking that that's where all my iron
went, although I can't explain how or why. I've been totally unable to get
water sprite established (the gouramis may be a contributing factor there)
and the crypts aren't spreading. The fish are all fine.

SO... Do I lower the Ph and Kh and, if so, how? And how do I keep them down?
If anyone has product recommendations I would be grateful, preferably online
in the U.S., as there are no intelligent life-forms in my local shops.



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Old 20-04-2003, 06:12 AM
Dave Millman
 
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Default Water Chemistry for Art Majors?

kush wrote:

It's been quite a few years since that chemistry class I never took, so if
someone could give me a hand here, I'd be grateful.

I've got a 75-gallon standard tank with 110 watts of lighting.


This is low for a plant tank, but acceptable as long as you don't inject CO2.

The tank has
lots of wood in it and is moderately to heavily planted and I'm injecting
CO2 through a powerhead and also with a diffuser next to the filter output.


Oops! High CO2 plus low light. This is an imbalance which often causes algae
soup.


I have a pretty heavy fish load for a planted tank, but my maintenance is
impeccable (imho).


Ph.............7.4-7.5
Nitrate.......not measurable
Nitrite........ 0.5 ppm
Gh.............3
Kh............. 12
Fe............. not measurable

I say the carbonate hardness is not measurable because after 12 drops it
just turns the same colour as the test liquid.


A bit of confusion perhaps...

Nitrate with an A is the end result of the nitrification cycle. It is extremely
unlikely that it is unmeasurable in a heavy fish load tank, although
measurements under 5ppm are common when the tank is also heavily planted.

Nitrite with an I is an intermediate product of the nitrification cycle. In a
mature tank, it goes to zero and stays there forever. It is also toxic to fish.
Is it possible you have reversed these measurements?

In any case, Plants cannot grow without Nitrate with an A, as it is an important
macronutrient. Given that you are dosing micronutrients such as Fe, you are
probably creating a substantial imbalance.

Regarding your KH and pH, these are probably not your problem, although it would
be interesting to know where all that KH is coming from. What kind of substrate
and stone is in the tank?

Recommendations: Your light level is too low for a CO2 tank. Either stop
injecting CO2 or double your lighting.

Untangle your test results to figure out actual levels of Nitrate with an A and
Nitrite with an I. If Nitrate is actually unmeasureable, you will have to dose
KNO3 to allow plant growth.

These links are all from the group FAQ:

Background on water hardness:
http://faq.thekrib.com/begin-chem.html

Lighting:
http://www.thekrib.com/Lights/
http://faq.thekrib.com/plant-lighting.html

Nitrate and test kits:
http://faq.thekrib.com/begin-tests.html




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Old 20-04-2003, 06:12 AM
kush
 
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Default Water Chemistry for Art Majors?

Whoops! Right you are, I have my "N's" reversed. That was embarrassing. I
agree that Nitrate is unlikely to be the problem. The stats were provided in
order to rule it out but, instead, I just made it even less clear.
Apologies.

I'm dosing with Fe because it's all being used, and I'm trying to give my
plants a leg up on the algae. Is that wrong?

I've actually stepped back my lighting from 220 watts but am adding CO2
because it helps lower my Ph and, according to the "Determination of CO2
Content in Aquarium Water" table I'm using, with ph of 7.5 and Kh of oh,
say, 15, I expect the CO2 content to be about 11 mg per quart which would be
at the low end of desirable, or do I have that muddled?

I'm still getting around the idea of carbonate hardness which I had rather
thought in my muddled way to have been subject to "manipulation" as opposed
to Gh aka permanent hardness which is, well, permanent. At any rate, I'm
using coarse gravel out of a bag from Petco, brand and chemical composition
long since forgotten, but the standard stuff.

At any rate, thank you very much for your help. It was not the answer I
expected and, in my experience, those are almost invariably the ones which
are correct.

One last question. Would you even attempt to maintain a Ph at around 7 if
it comes out the spigot at around 8?

Thanks,
kush

"You can't have everything - where would you put it?"

Dave Millman wrote in message
...
kush wrote:

It's been quite a few years since that chemistry class I never took, so

if
someone could give me a hand here, I'd be grateful.

I've got a 75-gallon standard tank with 110 watts of lighting.


This is low for a plant tank, but acceptable as long as you don't inject

CO2.

The tank has
lots of wood in it and is moderately to heavily planted and I'm

injecting
CO2 through a powerhead and also with a diffuser next to the filter

output.

Oops! High CO2 plus low light. This is an imbalance which often causes

algae
soup.


I have a pretty heavy fish load for a planted tank, but my maintenance

is
impeccable (imho).


Ph.............7.4-7.5
Nitrate.......not measurable
Nitrite........ 0.5 ppm
Gh.............3
Kh............. 12
Fe............. not measurable

I say the carbonate hardness is not measurable because after 12 drops it
just turns the same colour as the test liquid.


A bit of confusion perhaps...

Nitrate with an A is the end result of the nitrification cycle. It is

extremely
unlikely that it is unmeasurable in a heavy fish load tank, although
measurements under 5ppm are common when the tank is also heavily planted.

Nitrite with an I is an intermediate product of the nitrification cycle.

In a
mature tank, it goes to zero and stays there forever. It is also toxic to

fish.
Is it possible you have reversed these measurements?

In any case, Plants cannot grow without Nitrate with an A, as it is an

important
macronutrient. Given that you are dosing micronutrients such as Fe, you

are
probably creating a substantial imbalance.

Regarding your KH and pH, these are probably not your problem, although it

would
be interesting to know where all that KH is coming from. What kind of

substrate
and stone is in the tank?

Recommendations: Your light level is too low for a CO2 tank. Either stop
injecting CO2 or double your lighting.

Untangle your test results to figure out actual levels of Nitrate with an

A and
Nitrite with an I. If Nitrate is actually unmeasureable, you will have to

dose
KNO3 to allow plant growth.

These links are all from the group FAQ:

Background on water hardness:
http://faq.thekrib.com/begin-chem.html

Lighting:
http://www.thekrib.com/Lights/
http://faq.thekrib.com/plant-lighting.html

Nitrate and test kits:
http://faq.thekrib.com/begin-tests.html






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Old 20-04-2003, 06:12 AM
Jeff Ludwig
 
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Default Water Chemistry for Art Majors?

Oops! High CO2 plus low light. This is an imbalance which often causes
algae
soup.


I would disagree here. I have never heard of anyone implicating CO2 in
algae issues. More is better, even for low light tanks, the same can likely
be said about potassium. In fact, Tom Barr's recommended levels work great
on low light tanks... you get into problems when you're below those levels
and light is too high. I must agree however, not enough light.

In any case, Plants cannot grow without Nitrate with an A, as it is an

important
macronutrient. Given that you are dosing micronutrients such as Fe, you

are
probably creating a substantial imbalance.


I believe she's seeing NO2 because her plants are rotting away due to lack
of light. NH4 should not even get a chance to be converted to NO2 if light
levels are okay.

Regarding your KH and pH, these are probably not your problem, although it

would
be interesting to know where all that KH is coming from. What kind of

substrate
and stone is in the tank?


Recommendations: Your light level is too low for a CO2 tank. Either stop
injecting CO2 or double your lighting.


Again, as above, I think this is bad advice. Do increase lighting to keep
plants alive, no need to stop CO2.

Cheers,
Jeff Ludwig


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Old 20-04-2003, 06:12 AM
Jeff Ludwig
 
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Default Water Chemistry for Art Majors?

I'm dosing with Fe because it's all being used, and I'm trying to give my
plants a leg up on the algae. Is that wrong?


In order of importance, fix light levels, then CO2, NO3/PO4/K+ then finally
play around with traces. Traces are just that trace and have little effect
on anything unless the big nutrients, CO2 NO3/PO4/K are taken care of.

I've actually stepped back my lighting from 220 watts but am adding CO2


Can you get somewhere in between 220 and 110? Around 150 would be great,
3 55W PCFs maybe. 220W might be a little challenging, but it's very
possible to get things balanced.

because it helps lower my Ph and, according to the "Determination of CO2
Content in Aquarium Water" table I'm using, with ph of 7.5 and Kh of oh,
say, 15, I expect the CO2 content to be about 11 mg per quart which would

be
at the low end of desirable, or do I have that muddled?


At a KH of 15 I would be shooting for a pH of 7.2... neutral 7 might be a
little too far, you may see some fish getting stressed. Ideally you want
25-30ppm if you can, I don't care what kind of lighting you have.

I'm still getting around the idea of carbonate hardness which I had rather
thought in my muddled way to have been subject to "manipulation" as

opposed
to Gh aka permanent hardness which is, well, permanent. At any rate, I'm
using coarse gravel out of a bag from Petco, brand and chemical

composition
long since forgotten, but the standard stuff.


All these terms stink, and I hate that aquarium literature uses them. "dKH"
is really alkalinity, a measure of the total amount of base present in your
water. "General Hardness" is the amount of Ca++ and Mg++ in your water
(actually includes other divalent cations too, but they are not very
common).

Give http://www.sfbaaps.com/reference/barr_02_01.shtml a read. You may find
you need to bring the KH down by using an RO system over the long haul, 15
dKH is a lot. Stick with vallisneria and egeria densa, and the true
aquatics if you water is this basic, also any plants that grow near Lake
Tang would be pretty good... a lot of the amazon/soft water marsh plants may
grow more slowly than usual.

Cheers,
Jeff Ludwig




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Old 20-04-2003, 06:12 AM
Dave Millman
 
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Default Water Chemistry for Art Majors?

Jeff Ludwig wrote:

Recommendations: Your light level is too low for a CO2 tank. Either stop
injecting CO2 or double your lighting.


Again, as above, I think this is bad advice. Do increase lighting to keep
plants alive, no need to stop CO2.


You are correct. I stand corrected.

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Old 20-04-2003, 06:12 AM
kush
 
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Default Water Chemistry for Art Majors?

Jeff, Dave, first I'm going to apologize for being a cretin and then I'm
going to try to give you my correct parameters one more time before I let
you get on with your lives. My two-year old is sleeping now, so I hope to
be able to actually read this through before I hit the "send" button...

I have 190 watts, that's one hundred & ninety watts, that's 2 40 watt
standard flourescents at ?k in an AllGlass 48" twin strip plus 2 55 watt
compacts at 5300k retrofitted into an AllGlass 48" twin strip.

The lights are turned on for 12 1/2 hours a day. I keep the temperature down
about 72 in an attempt to brake the algae, which probably ****es off my
angels.

My Nitrite with an "i" is not measurable, and my nitrate with an "a" is less
than 0.5 ppm.

So, if my lighting and CO2 is alright (yes?), Gh and Kh are wacko but not
fatal, trace is added in accordance with packaging instructions or when Fe
is not detectable by testing, and "N"s are within acceptable limits, where
do I stand in the algae battle?

Reduce the daytime to 11 hours? Any recommendations on tamping down the Ph
without adding bisodium phosphate, or are phosphates OK with low nitrate
with an "a"? Anything else you can think of?

Thanks for your time. Do you find it difficult to give people useful advice
when they haven't given you useful information?

kush

"You can't have everything - where would you put it?"

Jeff Ludwig jeff at rockytop_dot_net wrote in message
...
Oops! High CO2 plus low light. This is an imbalance which often causes

algae
soup.


I would disagree here. I have never heard of anyone implicating CO2 in
algae issues. More is better, even for low light tanks, the same can

likely
be said about potassium. In fact, Tom Barr's recommended levels work

great
on low light tanks... you get into problems when you're below those levels
and light is too high. I must agree however, not enough light.

In any case, Plants cannot grow without Nitrate with an A, as it is an

important
macronutrient. Given that you are dosing micronutrients such as Fe, you

are
probably creating a substantial imbalance.


I believe she's seeing NO2 because her plants are rotting away due to lack
of light. NH4 should not even get a chance to be converted to NO2 if

light
levels are okay.

Regarding your KH and pH, these are probably not your problem, although

it
would
be interesting to know where all that KH is coming from. What kind of

substrate
and stone is in the tank?


Recommendations: Your light level is too low for a CO2 tank. Either stop
injecting CO2 or double your lighting.


Again, as above, I think this is bad advice. Do increase lighting to keep
plants alive, no need to stop CO2.

Cheers,
Jeff Ludwig




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Old 20-04-2003, 06:12 AM
Iain Miller
 
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Default Water Chemistry for Art Majors?

Biggest concern would be that your water has been through a domestic water
softener - this is NOT good for fish (if you have them). Domestic water
softeners work on an ionisation basis & basically strip the GH from the
water but don't touch the KH. Canb you not take a feed to a tap from in
front of the water softener?

I.


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Old 20-04-2003, 06:12 AM
 
Posts: n/a
Default Water Chemistry for Art Majors?

The PH and CO2 affect the KH. If you test your tap water you will probably
find that the KH is lower than it is in your tank.

Recommendation: Lower PH and see what effect that has on the KH and FE. Go
ahead and reduce period of lighting to 11 hours and keep thermostat as low
as you can without hurting the fish.

Can anyone comment on adding Bisodium Phosphate to a tank with an
established algae problem?

Regards, Snark

First get the
kush wrote in message
...
Jeff, Dave, first I'm going to apologize for being a cretin and then I'm
going to try to give you my correct parameters one more time before I let
you get on with your lives. My two-year old is sleeping now, so I hope to
be able to actually read this through before I hit the "send" button...

I have 190 watts, that's one hundred & ninety watts, that's 2 40 watt
standard flourescents at ?k in an AllGlass 48" twin strip plus 2 55 watt
compacts at 5300k retrofitted into an AllGlass 48" twin strip.

The lights are turned on for 12 1/2 hours a day. I keep the temperature

down
about 72 in an attempt to brake the algae, which probably ****es off my
angels.

My Nitrite with an "i" is not measurable, and my nitrate with an "a" is

less
than 0.5 ppm.

So, if my lighting and CO2 is alright (yes?), Gh and Kh are wacko but not
fatal, trace is added in accordance with packaging instructions or when Fe
is not detectable by testing, and "N"s are within acceptable limits, where
do I stand in the algae battle?

Reduce the daytime to 11 hours? Any recommendations on tamping down the

Ph
without adding bisodium phosphate, or are phosphates OK with low nitrate
with an "a"? Anything else you can think of?

Thanks for your time. Do you find it difficult to give people useful

advice
when they haven't given you useful information?

kush

"You can't have everything - where would you put it?"

Jeff Ludwig jeff at rockytop_dot_net wrote in message
...
Oops! High CO2 plus low light. This is an imbalance which often causes

algae
soup.


I would disagree here. I have never heard of anyone implicating CO2 in
algae issues. More is better, even for low light tanks, the same can

likely
be said about potassium. In fact, Tom Barr's recommended levels work

great
on low light tanks... you get into problems when you're below those

levels
and light is too high. I must agree however, not enough light.

In any case, Plants cannot grow without Nitrate with an A, as it is an

important
macronutrient. Given that you are dosing micronutrients such as Fe,

you
are
probably creating a substantial imbalance.


I believe she's seeing NO2 because her plants are rotting away due to

lack
of light. NH4 should not even get a chance to be converted to NO2 if

light
levels are okay.

Regarding your KH and pH, these are probably not your problem,

although
it
would
be interesting to know where all that KH is coming from. What kind of

substrate
and stone is in the tank?


Recommendations: Your light level is too low for a CO2 tank. Either

stop
injecting CO2 or double your lighting.


Again, as above, I think this is bad advice. Do increase lighting to

keep
plants alive, no need to stop CO2.

Cheers,
Jeff Ludwig






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Old 20-04-2003, 06:12 AM
Iain Miller
 
Posts: n/a
Default Water Chemistry for Art Majors?

Xref: 127.0.0.1 rec.aquaria.freshwater.plants:66029


"[email protected]" wrote in message
...
The PH and CO2 affect the KH. If you test your tap water you will probably
find that the KH is lower than it is in your tank.

Recommendation: Lower PH and see what effect that has on the KH and FE. Go
ahead and reduce period of lighting to 11 hours and keep thermostat as low
as you can without hurting the fish.

Can anyone comment on adding Bisodium Phosphate to a tank with an
established algae problem?


CO2 does NOT affect KH.

There is a direct relationship between CO2, Ph & KH

If you add CO2 the PH will drop - the KH will stay constant

If you take it away, the reverse happens

Things that affect KH are things like limestone in the tank which will raise
it (and with it the Ph at a given CO2 level.

Over time KH will gradually decrease as the buffer gets eaten up (all other
things being equal)....this will mean that your PH will gradually fall with
it at a given level of CO2. When KH gets to 0 then PH will crash. At KH
levels of below 2gDh KH becomes much less stable.

KH is much harder to move than either PH or CO2 levels. As above, add CO2 &
PH drops quite quickly - KH won't move.

Raise KH by having some source of calcium in the tank, lower it by filtering
through peat.

HTH

I.





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Old 20-04-2003, 06:12 AM
kush
 
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Default Water Chemistry for Art Majors?

I checked. My household water supply (artisian well w/ water softener) has a
Ph of 8 and the Kh measures 8 right out of the tap.

When I test my aquarium water the Ph is about 7.4 or 7.5 and the Kh is over
12. I can't tell the exact degree because the vial turns the same colour
as the test fluid.

I have no limestone in my tank, just coated aquarium gravel out of a bag and
ceramic bio rings in the filter.

Will peat discolour my water? Do I buy it at a garden center and stuff it in
a media bag and put it in my cannister filter? WILL bisodium phosphate
cause my algae to boom? Should I find a new hobby?

My plants are mostly thriving and my fish appear healthy. It's just that the
algae is slowly gaining ground...

Thanks all.

Iain Miller wrote in message
...

"[email protected]" wrote in message
...
The PH and CO2 affect the KH. If you test your tap water you will

probably
find that the KH is lower than it is in your tank.

Recommendation: Lower PH and see what effect that has on the KH and FE.

Go
ahead and reduce period of lighting to 11 hours and keep thermostat as

low
as you can without hurting the fish.

Can anyone comment on adding Bisodium Phosphate to a tank with an
established algae problem?


CO2 does NOT affect KH.

There is a direct relationship between CO2, Ph & KH

If you add CO2 the PH will drop - the KH will stay constant

If you take it away, the reverse happens

Things that affect KH are things like limestone in the tank which will

raise
it (and with it the Ph at a given CO2 level.

Over time KH will gradually decrease as the buffer gets eaten up (all

other
things being equal)....this will mean that your PH will gradually fall

with
it at a given level of CO2. When KH gets to 0 then PH will crash. At KH
levels of below 2gDh KH becomes much less stable.

KH is much harder to move than either PH or CO2 levels. As above, add CO2

&
PH drops quite quickly - KH won't move.

Raise KH by having some source of calcium in the tank, lower it by

filtering
through peat.

HTH

I.





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Old 20-04-2003, 06:12 AM
 
Posts: n/a
Default Water Chemistry for Art Majors?


Iain Miller wrote in message
...

CO2 does NOT affect KH.


Beg to differ. This is quoted from RedSea:

"CO2 gas dissolved in water can take the form of bicarbonate or carbonate.
These three forms are in chemical equilibrium. Which form is present in what
amount depends on pH.

Dissolved CO2 = bicarbonate ion = carbonate ion

In the pH range favorable to water plants, pH 6.4 - 7.2, a percentage will
be present as dissolved CO2 and the rest as bicarbonate ions.
From pH 8.0 to pH 8.8 there will be almost no dissolved CO2, a large amount
of bicarbonate and a small amount of carbonate."

From which I conclude that carbonate hardness can be reduced by lowering
either CO2 or pH.



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Old 20-04-2003, 06:12 AM
E. Mito
 
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Default Water Chemistry for Art Majors?

In article , "Iain Miller"
writes:


CO2 does NOT affect KH.

There is a direct relationship between CO2, Ph & KH

If you add CO2 the PH will drop - the KH will stay constant


Maybe you mean GH? CO2 won't affect GH (mainly dependent on Ca+2 and Mg+2 if I
understand correctly).



Erica
http://members.aol.com/_ht_a/mitoem/mitoem/index.htm

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Old 20-04-2003, 06:12 AM
James Purchase
 
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Default Water Chemistry for Art Majors?

Adding CO2 does NOT change Alkalinity (which is _really_ what you are
talking about when you use the term "KH".

Many people (and MANY websites, even commercial ones) confuse water hardness
and alkalinity and the terms they use to describe them only add to the
confusion. Both are normally given in ppm CaCO3. When water falls as rain,
the falling raindrops absorb CO2 from the atmosphere. Some of this dissolved
CO2 will form Carbonic Acid, giving the raindrop a slightly acid pH. Calcium
bearing rock is very common all over the world and when the rain percolates
thru the soil, it dissolves some of the CaCO3 contained in the soil.

When a mineral like CaCO3 dissolves in water, the molecule breaks apart,
into a Ca++ ion and a CO3-- ion. The Ca++ is the ion responsible for water
hardness and the CO3-- ion is responsible for alkalinity (KH if you prefer).
In _most_ natural bodies of water, the alkalinity is all due to "Carbonate
Hardness" (the German word for this is where "KH" comes from). So, when you
measure "hardness", you are getting the measure of the Ca++ ions in the
water (along with other ions with a ++ charge, like Magnesium). When you
measure "alkalinity" (KH), you are getting the measure of the CO3-- ions.
Note that the bicarbonate ion (HCO3-) is a "form" of the bicarbonate ion -
see below.

Water not only has the ability to dissolve most minerals to some extent,
breaking the molecules apart into the constituent ions, it also breaks apart
itself, to some extent (not much - most of the molecules in a glass of water
are still H2O). When water disassociates, it becomes H+ and OH- ions. The H+
ions don't really exist in solution as naked protons (which is what you are
left with when an atom of Hydrogen loses its single electron) - they join
together loosely with water molecules forming H3O+. As a quick shorthand, H+
= H3O+.

Some of those "naked protons" (the H+ ions) can react with carbonate ions
(the CO3-- ions), forming bicarbonate ions (HCO3-). There is a direct
equilibrium relationship between dissolved CO2, pH, HCO3- and CO3--. If you
add CO2 the ratio of HCO3- to CO3-- will change, but the total amount of
[(HCO3-) + (CO3--)] doesn't change. The pH of the water will change as the
number of H+ ions varies (pH is the negative log of [H+]).

When you add CO2 to an aquarium, the pH will drop. How FAR it will drop
depends upon the Alkalinity of the water. In a water supply that has a
moderate Alkalinity, the pH will be held pretty constant, only dropping
slightly. If there was no Alkalinity in the water, the addition of CO2 would
cause the pH to crash, endangering your fish. You can increase your water's
Alkalinity by adding Baking Soda (NaHCO3) if necessary.

In a planted aquarium, it isn't necessary to shoot for a "specific" pH. I
see many questions from people worrying about how to get the pH "down" to
some specific number. This really isn't needed. Depending upon your water's
Alkalinity, adding CO2 can depress the pH - but it isn't the drop in pH
which is important. What is important for the plants is the increase in
dissolved CO2. You can use the charts on the KRIB to see how much CO2 is in
your water at varying alkalinity (KH) levels and pH values.

This is the Carbonate-Bicarbonate buffer system and is the primary buffering
system in most natural bodies of water. Other chemicals _can_ influence the
pH of the water. The one most frequently encountered by aquarists is
Phosphates. This is what is contained in products like "pH Down". Phospate
buffers can lower the pH but they will have absolutely NO EFFECT on the
level of CO2 in the water. You can't use it as a short cut or a substitute
for adding CO2. Excess phosphates can also contribute to problems with
algae.

Enough chemistry?

James Purchase
Toronto

"[email protected]" wrote in message
...

Iain Miller wrote in message
...

CO2 does NOT affect KH.


Beg to differ. This is quoted from RedSea:

"CO2 gas dissolved in water can take the form of bicarbonate or carbonate.
These three forms are in chemical equilibrium. Which form is present in

what
amount depends on pH.

Dissolved CO2 = bicarbonate ion = carbonate ion

In the pH range favorable to water plants, pH 6.4 - 7.2, a percentage will
be present as dissolved CO2 and the rest as bicarbonate ions.
From pH 8.0 to pH 8.8 there will be almost no dissolved CO2, a large

amount
of bicarbonate and a small amount of carbonate."

From which I conclude that carbonate hardness can be reduced by lowering
either CO2 or pH.





  #15   Report Post  
Old 20-04-2003, 06:12 AM
kush
 
Posts: n/a
Default Water Chemistry for Art Majors?

Thanks to everyone who offered advice and I apologize if I started any
fights. Since last we spoke, I've added two 2"-to-3" pl*cos and cut back
the lighting to eleven hours. File under "Weird but True:" By visual
inspection, the amount of algae in my tank is reduced by roughly half since
Friday. I doubt it was two days of reduced lighting, but whether it was the
double-dose of iron or the pl*cos, or some process already under way, or all
of the above, my optimism has been (at least temporarily) restored. Now if
I can just stabilize it...

Thanks again,
kush

"You can't have everything - where would you put it?"

I've never
kush wrote in message
...
It's been quite a few years since that chemistry class I never took, so if
someone could give me a hand here, I'd be grateful.

I've got a 75-gallon standard tank with 190 watts of lighting. The tank

has
lots of wood in it and is moderately to heavily planted and I'm injecting
CO2 through a powerhead and also with a diffuser next to the filter

output.
I have a pretty heavy fish load for a planted tank, but my maintenance is
impeccable (imho).

Forty-eight hours after it's weekly 20% water change and adding double the
recommended dosage of trace iron, my stats a

Ph.............7.4-7.5
Nitrite.......not measurable
Nitrate........ 0.5 ppm
Gh.............3
Kh............. 12
Fe............. not measurable

I say the carbonate hardness is "more than" 12 because after 12 drops it
just turns the same colour as the test liquid.

My water comes from a well which feeds into a water softener in the
basement. There is no practical way to bypass the water softener.

My specific concern is algae, and I've got a small, tolerable amount every
kind I've ever heard of and then some. The plants are all doing "OK" but
I'm afraid that things might be starting to slip away from me, despite two
2" plecos, a dozen ottocats and a host of snails of every race, creed and
colour.

Paradoxically (perhaps), the Red-spot Ozelot and the Hygro Corymbosa are
vividly red and thriving, so I'm thinking that that's where all my iron
went, although I can't explain how or why. I've been totally unable to get
water sprite established (the gouramis may be a contributing factor there)
and the crypts aren't spreading. The fish are all fine.

SO... Do I lower the Ph and Kh and, if so, how? And how do I keep them

down?
If anyone has product recommendations I would be grateful, preferably

online
in the U.S., as there are no intelligent life-forms in my local shops.






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