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MTS out of control



 
 
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  #61  
Old October 8th 04, 05:44 AM
Trapper
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"Dan White" wrote in message . net...
"TYNK 7" wrote in message
...

As for Cardinals..I honestly do not know if they would fair well in hard

water
or not.
I might assume they'd be like the neons....but then again you really can't
always assume in this hobby.
NetMax....what sa you about Cardinals and hard water?


I have very hard water in NJ...got 6 cardinals about 2 months ago and they
are all doing just fine. I had cardinals years ago as a kid in the same
area and they had no problem with the hard water.

dwhite


Howdy again,

I'm across the river in Manhattan, and the water here, according to an
assay from 2003 I saw on the web, is about 1.2DH. That's fairly soft,
I reckon, and the pH is supposed to test out at about 7.2.

I *think* my water conditions here wouldn't take much tweaking to get
down to mid-6 pH and 2-3 DH that the tetras seem to like for breeding.
The best case scenario would be for my would-be flock of cardinals to
get to breeding condition. Other than a possible nitrate and
phosphate spike in NYC tap water, there seem to be few problems. I
think water changes and plants will keep these under control.

Has anyone had good freshwater experience with wet/dry? That was a
big part of my original post, not so far addressed.

Thanks!

--Trapper
  #62  
Old October 10th 04, 07:11 PM
Dean A. Markley
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Eric, I will take some of those snails off your hands! Will that help?
Also, a few native sunfish will help keep them down. Redbreasts are
snaileaters.

Dean

"Eric Schreiber" eric at ericschreiber dot com wrote in message
...
Quite some time ago (a year or more) I was given a handful of Malaysian
Trumpet snails by a local fish store. I counted perhaps a hundred. Most
went into my heavily planted 20 gallon community tank, where they've
done quite well for themselves.

Quite well, indeed.

I estimate I now have several thousand, still in that same 20 gallon
tank. The tank, fish and plants are all quite healthy, and the MTS
certainly aren't hurting anything that I can see. But their population
is extremely out of control.

I can literally see my substrate (Flourite gravel) moving, almost
constantly. Especially in the hour or so before the lights go off. It
probably isn't an exaggeration to say that 1/5 of the volume of my
substrate is actually MTS.

A bit of web searching turns up clown loaches as the best 'natural'
approach to dealing with these snails. I don't expect that they could
wipe the population out, and for that matter, I don't want to wipe the
MTS out - just reduce their numbers a lot.

According to the sites I've read, clown loaches are apparently ok in a
community tank, and will grow fairly slowly.


--
Eric Schreiber
www.ericschreiber.com



  #63  
Old October 20th 04, 04:14 AM
NetMax
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"Trapper" wrote...
"NetMax" wrote...
"Trapper" wrote...
"NetMax" wrote...
"Trapper" wrote...
"Dan White" wrote ...
"TYNK 7" wrote...
[snippety-snip]


I made a trip to my LFS on Friday before sundown, and the
reasonably-clueful (but interested in selling me stuff) LSF-guy
claimed that the shop's tetras do well in their slightly alkaline
(7.2ish) water. This guy tried to sell me on the idea of getting a
tapwater purifier doodad (not RO) to pull metals, etc., from my
tapwater, and to soften it somewhat, saying it is indispensible for
the tetras and planted tank I wish to maintain. The gizmo is $70, so
I might just say "what the heck."


I'm always sceptical about tapwater purifiers. Most of what I've seen
were softener pillows which needed to be recharged, or types of
zeolite/activated carbon, which also had a finite operating life. If the
natural conditions are fish-adaptable, then it's less work & expense to
keep them that way.

He also tried to sell me a $799 lighting hood, so the appropriate
grains of salt have been taken.

It is my opinion that osmotic pressure is of far greater interest to

the
hobbyist when keeping small river fish like Cardinal tetras. Rapid
changes in the gH which would be damaging to other larger or more

hardy
fish, will be fatal to small tetras, often resulting in an epidemic

of
some contagion (Ich, Velvet and fin rot seem to be the most

prevalent).

If I end up getting the aforementioned water purifier doodad, and if
its effectiveness doesn't vary wildly during use, I think I should be
able to keep my water-change water chemistry pretty consistent. Any
evaporative losses will be topped off by commercially-supplied
distilled/deionized water, so I think I won't have much to worry about
in terms of *increasing* hardness. The plants could have a softening
effect, though, so I'll just have to keep testing. And I'll remember
your idea of keeping some coral on hand just in case.


In theory, I'm in agreement, but the ability to use copious amounts of
source water is an extremely valuable tool which I'm always reticent to
give up. As soon as you sucumb to massaging your water's parameters to
anything different than source, then you relinquish part of your
abilities and accept some limitations. A new hobbyist is well advised to
change as little as possible. For everyone else, it's at your
discretion, based on experience, confidence and the application.

Also, I haven't ruled out the idea of getting an RO unit, and using
commercially-available reconstituting solutions with its output. The
tapwater here has a fair amount of nitrates and phosphates, and it
seems like it could be worthwhile to keep those as low as possible to
prevent algal blooms. Then again, pulling enough C02 in the tank to
get to pH 6 might give the plants all the leg-up they need.


Nitrates are not a problem in low-fishload planted tanks. Some hobbyists
add nitrates in these conditions. Also phosphates can be removed with a
phosphate pillow if the need arose (just fyi).

Anecdotally, I was keeping Neon tetras [and lots of 'em, in 7.7pH,

3dgH 2dkH
water].


This leads me to believe that I'm just a wee bit needlessly worried.

Later [Cards kept in a standard tank at 7.7pH and they did great].
[***] At 7.7pH, this brings us to almost 4 orders of magnitude, but

_note_ my
hardness was 3dgH, and I think this was a big contributor.


The idea this gives me is that there's got to be a 3-dimensional (at
least) matrix from which can be computed some useful single parameter
for one's water. In other words, you plug in pH, gH, kH, and out
comes some number. And let's say your fishies need that number in a
certain range. I'm not sure how I'd go about calculating this number,
we may have to just see who keeps happy tetras and just figure it out
empirically.


Interesting idea, though I think it would be better described as fishies
needing to avoid a number range, rather than being in a number range, as
they are exremely adaptable if the changes occur gradually (just as they
would in a larger body of water than your typical aquarium ;~).

[The coral buffer idea]
My translation of what this means is that if my tapwater has little
buffering capacity, as carbonate, then addition of some buffering
capability to the system as a whole is indicated. This suggestion

is
facially sound; one wants to keep a hedge against the dreaded pH
crash, notwithstanding sources positing Cardinals' acid tolerance,
supra.


Correct, though not all buffering agents are created equally ;~)


Right. One must select the buffering system for effectiveness at the
desired pH (among other factors). If I mind my Ps and Qs, I think I
can get away with the carbonic acid/carbonate buffers at pH 6. And if
I'm wrong, I'm sure someone will tell me. g


Not me, I've only been doing the stuff for just over 30 years, so I'm
still learning.

I think the coral itself won't really be touched significantly

unless
there is in the tank an acidifying force capable of exhausting the

tap
water's inherent buffering capacity between water changes.


Typically, the primary acidifying effect will be [the obvious].

Trade
doctrine for the 'fence' is 4dkH, below which you need to be far more
cautious.


Seems to me that the caution is against pH crash. And it seems also
that if one's hell-bent on using really soft water for some purpose,
it is a good idea to have a quite large system with small biological
load.

I wouldn't want to play around with really soft water at pH 5.5 in a
10-gal tank with 5 fish, but I suspect the danger would be much
lessened in a 6-foot tank.


Yes and no. On the surface, yes, as every change or risk of imbalance is
magnified by a greater fishload (smaller tank), and larger tanks (100g+)
move (parametrically) very slowly, almost establishing their own
biotope-like balance if allowed to, but (there is always a but).... If
it takes more time to 'affect' a larger tank, they also have much more
momentum, so that the intitial correctve actions often appears
ineffective. Coupled with the hobbyist's more relaxed approach with
larger tanks (and who can blame us after so many test results appear so
constant), that we sometimes get caught unawares ;~).

[snippety-snip]


The only possible snag I see is if I eventually employ a C02

system.
In particular, I wonder if a w/d trickle filter is *too* good at
performing outgassing, and, if so, whether I'd lose much of the CO2
benefit as a result.


I think we have similar opinion on the pros & cons, including the

concern
about outgassing the extra CO2.


The LFS people were of somewhat divided opinion as to w/d filters in
CO2-equipped planted tanks. Consensus was mildly against, due to
exactly this concern about CO2 outgassing.


Speaking as a customer, LFS manager and a fish-dept personnel trainer,
I've never held the opinions of LFS personnel in high esteem. I do trust
the newgroups to point me in more accurate and measurable directions.

That said, I have given this some thought and I do believe it is
possible, at the expense of additional CO2, to keep the plants
supplied with as much of the dissolved gas as they need - even while
using a w/d filter. This I predicate on the assumption that the w/d
will not be able to outgas 100% of dissolved C02; there will be *some*
amount, addable to the tank, which even after dissipation by the w/d
will end up being proper. There's no calculable approach I can think
of to determining this level, and I'd just have to titrate.


LOL on titrate, never heard it put this way, though it reasonably
describes the process if using a pressurized CO2 canister. If use yeast
reaction, you will be more limited on how much CO2 you can afford to have
dissipated. In any case, try to minimize your surface turbulence or you
will have another CO2 sink to compensate for.

snip
If I target a pH of, say, 6 (and my gut feeling is that it can safely
be done) I'm not too worried about affecting the fishies adversely.
I'll bet that within reason dissolved C02 won't displace dissolved O2,
and the Cards will be fine.


Yes, I've also read that O2 displacement by CO2 does not significantly
occur in these applications. If your interest has you curious, would
using a nitrogen/CO2 mix be more advantageous? I wonder what the plants
would think of that? It would be a more natural mixture (as a ratio to
CO2, not O2).
--
www.NetMax.tk

[snip]



--Trapper



  #64  
Old October 22nd 04, 03:08 PM
Trapper
external usenet poster
 
Posts: n/a
Default

"NetMax" wrote in message m...
"Trapper" wrote...
"NetMax" wrote...
"Trapper" wrote...
"NetMax" wrote...
"Trapper" wrote...
"Dan White" wrote ...
"TYNK 7" wrote...
[snippety-snip]



[I wrote about tapwater purifiers, and RO units]


I'm always skeptical about tapwater purifiers. Most of what I've seen
were softener pillows which needed to be recharged, or types of
zeolite/activated carbon, which also had a finite operating life. If the
natural conditions are fish-adaptable, then it's less work & expense to
keep them that way.


I've finally begun, slowly, to analyze my tapwater. The results so
far have been interesting:
pH @ zero time: 7.0
pH @ 17hrs: ~7.2 (guesstimate; my test kit has 0.5pH increments)

KH: 0.8

I've yet to test for GH, so the picture's not really complete. My
feeling, which I base solely on published NYC water analyses, is that
GH is not going to be very high at all. The upshot of this is that,
at least with respect to KH and GH, an RO unit or tapwater purifier is
not going to buy me any advantages at all.

It's still an open question whether it'd be worthwhile for nitrates
(reportedly ~0.2 ppm out of the tap) and phosphates (reportedly ~2.1
ppm out of the tap) and metals (unknown).

Time to scope out a source of reagent-grade bicarb and CaCO3.

[snip]


[I muse about tapwater purifiers, RO units, water-change water consistency,
and topping off evaporative losses with RO]


In theory, I'm in agreement, but the ability to use copious amounts of
source water is an extremely valuable tool which I'm always reticent to
give up. [Tinkering with it is] at your discretion, based on experience,
confidence and the application.


Based on the result of my KH testing, I'm sufficiently concerned with
the buffering capacity of my water that I think I'll be forced to do
*some* kind of modifications of the tapwater. Point taken, though;
simplicity with this most fundamental component of the system is to be
sought where possible.

[More on RO, nitrates, phosphates, and plants]


Nitrates are not a problem in low-fishload planted tanks. Some hobbyists
add nitrates in these conditions. Also phosphates can be removed with a
phosphate pillow if the need arose (just fyi).


Okay, I am now tending toward the conclusion that the chief, if not
entire, utility of an RO unit for me will be to produce water suitable
for replacement of evaporative losses. Given the price here in NYC of
a gallon of distilled water (several bucks, when you can find it)
it'll be cost-effective in no time for me to get a $120 RO unit.


Anecdotally, I was keeping Neon tetras [and lots of 'em, in 7.7pH,
3dgH 2dkH water].


There's got to be a chemistry lesson in this. Running your pH and kH
through the formula:
[CO2] = 3 * (kH) * 10^(7-pH)
where kH = 36 ppm
gives [CO2] ~ 1.2 ppm. Ambient [CO2] is said to be 3-5 ppm.

It must be that there is other buffer funkiness going on in that
system. Perhaps a significant buffer sink other than carbonate?
Plants eating CO2 faster than the passive diffusion rate from
air-water?

[snip]


The idea this gives me is that there's got to be a 3-dimensional (at
least) matrix from which can be computed some useful single parameter
for one's water. [***]


Interesting idea, though I think it would be better described as fishies
needing to avoid a number range, rather than being in a number range, as
they are exremely adaptable if the changes occur gradually (just as they
would in a larger body of water than your typical aquarium ;~).


I think of this in just the same terms as an aircraft's flight
envelope. There are certain parts where it's no-go. Elsewhere,
you're fine with the right adaptations.

[The coral buffer idea]

I'm planning to use a pH controller to drive my CO2 system. With this
I will have to be veeeeeery careful. It strikes me that if I've got
an arbitrarily large CaCO3 source (like a hunk o' coral) and a
feedback look controlling CO2 generation, I could end up with a race
condition: the end point would be fantastic CO2 concentration, skyhigh
kH, and dead fish.

So, that either imposes on me the duty to watch the foregoing system
like a hawk and withdraw the coral when kH is right, OR I'll just have
to get reagent-grade powdered chemicals to add in known quantities.


Yes and no. On the surface, yes, as every change or risk of imbalance is
magnified by a greater fishload (smaller tank), and larger tanks (100g+)
move (parametrically) very slowly, almost establishing their own
biotope-like balance if allowed to, but (there is always a but).... If
it takes more time to 'affect' a larger tank, they also have much more
momentum, so that the intitial correctve actions often appears
ineffective. Coupled with the hobbyist's more relaxed approach with
larger tanks (and who can blame us after so many test results appear so
constant), that we sometimes get caught unawares ;~).


The proper way to approach this large-tank complacency, then, is to
use really precise (and accurate) test kits, and use them frequently.
Key, too, is to produce a log and/or graphical representation of the
parameters. With really fastidious data collection, I think one
stands a better chance of seeing if a smal variation in a test result
is within the "noise" to be expected.



[snippety-snip]



snip
If I target a pH of, say, 6 (and my gut feeling is that it can safely
be done) I'm not too worried about affecting the fishies adversely.
I'll bet that within reason dissolved C02 won't displace dissolved O2,
and the Cards will be fine.


Yes, I've also read that O2 displacement by CO2 does not significantly
occur in these applications. If your interest has you curious, would
using a nitrogen/CO2 mix be more advantageous? I wonder what the plants
would think of that? It would be a more natural mixture (as a ratio to
CO2, not O2).


First, it would seem that my gut feeling, while technically correct,
would not have left me much wiggle room at all. At pH6, CO2 between
10-25 ppm (18ppm) you need to maintain kH of 0.6 (which I can't get,
even with my water, without diluting with RO). I certainly would NOT
want to play with kH=0.6 water in other than a quite large and
understocked tank.

Next, as to the idea of using an N2/CO2 mix for carbon dioxide
injection: I can think of a few reasons it mightn't be advantageous at
all. First, the tank water at large is already saturated with N2 from
the air, and available nitrogen *as nitrogen* is not important to a
system where nitrogen fixation is not taking place (e.g.
Rhizobium-using legumes in the terrestrial context). Second, a ten
pound tank of N2/CO2 contains less CO2, and I'd have to change it out
at a faster rate reflecting the proportion less than 100% of CO2 in
the mix.

Later, gator!
--Trapper
  #65  
Old October 22nd 04, 03:49 PM
Rocco Moretti
external usenet poster
 
Posts: n/a
Default

Trapper wrote:

[The coral buffer idea]


I'm planning to use a pH controller to drive my CO2 system. With this
I will have to be veeeeeery careful. It strikes me that if I've got
an arbitrarily large CaCO3 source (like a hunk o' coral) and a
feedback look controlling CO2 generation, I could end up with a race
condition: the end point would be fantastic CO2 concentration, skyhigh
kH, and dead fish.


Chemistry wonks can correct me if I'm wrong, but I don't think it will
be a big problem. In solution you have the reaction:
Carbonic acid = Bicarbonate = Carbonate
The interconversions are acid/base reactions, so they're fast, and thus
probably at equilibrium with each other. This means that at a given pH,
the ratios between all three are constant (due to the law of mass
action). You also have a large reserve of coral (calcium carbonate).
When it dissolves, it breaks up into calcium and carbonate. If the
reaction is at equilibrium, the product of the calcium and carbonate
concentrations is constant (also by mass action). Let's assume that the
water is allowed to equilibrate with calcium carbonate before you turn
on your CO2 regulator.

You turn on the CO2, and the pH is slightly high. CO2 is pumped into the
system. This reacts with water and turns into carbonic acid which turns
into bicarbonate (since the ratios were disturbed), which then turns
into carbonate, which then reacts with the (now) excess calcium ions,
and crashes out, which lowers the carbonate concentration, which allows
more carbon to flow this way from CO2. You just added 2 H+ ions
(lowering the pH), but didn't increase the kH as much as if the carbon
hit a wall at the carbonate, as some of it crashed out. It's also true
that you lowered the pH, thus increasing the proportion of carbonic acid
and bicarbonate in solution (compared to carbonate), but this increase
just means that the next CO2 molecule just won't make it all the way to
carbonate. What you are worried about (more coral will dissolve with
increased acid addition) won't likely happen.

It's true that if you add an acid (say, hydrochloric) to your tank, you
increase the amount of bicarbonate and carbonic acid in your tank, but
since there isn't a supply from CO2, it comes from the carbonate end,
which is replenished by the dissolving calcium carbonate. If you add
carbonic acid (CO2), this increase comes from the carbonic acid end instead.

This is all theoretical though. Can anyone confirm/refute my reasoning?

-Rocco
  #66  
Old October 23rd 04, 05:33 PM
NetMax
external usenet poster
 
Posts: n/a
Default

"Trapper" wrote...
"NetMax" wrote...
"Trapper" wrote...
"NetMax" wrote...
"Trapper" wrote...
"NetMax" wrote...
"Trapper" wrote...
"Dan White" wrote ...
"TYNK 7" wrote...
[snippety-snip]


[I wrote about tapwater purifiers, and RO units]


I'm always skeptical about tapwater purifiers. Most of what I've

seen
were softener pillows which needed to be recharged, or types of
zeolite/activated carbon, which also had a finite operating life. If

the
natural conditions are fish-adaptable, then it's less work & expense

to
keep them that way.


I've finally begun, slowly, to analyze my tapwater. The results so
far have been interesting:
pH @ zero time: 7.0
pH @ 17hrs: ~7.2 (guesstimate; my test kit has 0.5pH increments)

KH: 0.8


Your pH bump after outgassing sounds perfectly normal. The accuracy of
pH measurements (typical kit) is something like +- 0.4 absolute and 0.2
relative, so you're in the ballpark.

I've yet to test for GH, so the picture's not really complete. My
feeling, which I base solely on published NYC water analyses, is that
GH is not going to be very high at all. The upshot of this is that,
at least with respect to KH and GH, an RO unit or tapwater purifier is
not going to buy me any advantages at all.

It's still an open question whether it'd be worthwhile for nitrates
(reportedly ~0.2 ppm out of the tap) and phosphates (reportedly ~2.1
ppm out of the tap) and metals (unknown).

Time to scope out a source of reagent-grade bicarb and CaCO3.

[snip]


[I muse about tapwater purifiers, RO units, water-change water

consistency,
and topping off evaporative losses with RO]


In theory, I'm in agreement, but the ability to use copious amounts

of
source water is an extremely valuable tool which I'm always reticent

to
give up. [Tinkering with it is] at your discretion, based on

experience,
confidence and the application.


Based on the result of my KH testing, I'm sufficiently concerned with
the buffering capacity of my water that I think I'll be forced to do
*some* kind of modifications of the tapwater. Point taken, though;
simplicity with this most fundamental component of the system is to be
sought where possible.

[More on RO, nitrates, phosphates, and plants]


Nitrates are not a problem in low-fishload planted tanks. Some

hobbyists
add nitrates in these conditions. Also phosphates can be removed

with a
phosphate pillow if the need arose (just fyi).


Okay, I am now tending toward the conclusion that the chief, if not
entire, utility of an RO unit for me will be to produce water suitable
for replacement of evaporative losses. Given the price here in NYC of
a gallon of distilled water (several bucks, when you can find it)
it'll be cost-effective in no time for me to get a $120 RO unit.


I don't understand the concern over the replenishment of your evaporated
water. In a marine (and brackish applications to a lesser degree), there
is a requirement to know and maintain (to some degree), the specific
gravity of the water. Once the SG is known, replacing evaporated water
with distilled water maintains that SG. This is also somewhat applicable
to hard-water applications which are brutally unmaintained (only topping
up with hard water without doing water changes will cause the hardness to
continue rising). None of these situations are applicable to running a
soft water tank. The extreme is actually more applicable. When you top
up, add water with some minerals to prop your gH/kH balance again.

Anecdotally, I was keeping Neon tetras [and lots of 'em, in

7.7pH,
3dgH 2dkH water].


There's got to be a chemistry lesson in this. Running your pH and kH
through the formula:
[CO2] = 3 * (kH) * 10^(7-pH)
where kH = 36 ppm
gives [CO2] ~ 1.2 ppm. Ambient [CO2] is said to be 3-5 ppm.

It must be that there is other buffer funkiness going on in that
system. Perhaps a significant buffer sink other than carbonate?
Plants eating CO2 faster than the passive diffusion rate from
air-water?


LOL, you caught that. The 'buffer sink' was lots of fish (commercial
tanks). A commercial 60g tank receives Neon tetras in quantities of
about 500 at a time (when I though there was still close to 200, I'd
scale the delivery back to 400. Also the CO2 calculation is precise but
the variables are not. To maintain acceptable parameters, the Neon Tetra
tank (to continue using this as an example) received a 10% water change
every 6 hours (automated), and fresh water ranged from 7.5 to 7.8pH. The
titration test for kH is also very coarse, turning on the 3rd drop, so
the kH in ppm was between 36 and 54 (not a very exact multiplier). The
tank was also heavily planted (almost 100% of the surface with a 3" tall
Sunset hygrophilia), so it was not gravel vacuumed. Many things
contribute to the math and this was one of about 40 different tetra tanks
running low kH, moderate pH conditions.

[snip]
[The coral buffer idea]

I'm planning to use a pH controller to drive my CO2 system. With this
I will have to be veeeeeery careful. It strikes me that if I've got
an arbitrarily large CaCO3 source (like a hunk o' coral) and a
feedback look controlling CO2 generation, I could end up with a race
condition: the end point would be fantastic CO2 concentration, skyhigh
kH, and dead fish.

So, that either imposes on me the duty to watch the foregoing system
like a hawk and withdraw the coral when kH is right, OR I'll just have
to get reagent-grade powdered chemicals to add in known quantities.


The advantage of using natural modifiers (dolomite, limestone, tufa,
marble, coral etc) over chemical modifiers is their self-adjusting and
progressive rate of influence. For example, the rate at which coral
breaks down releasing carbonates is a non-linear function dependant on
the acidity of the water. The more acidic the water, the more active the
coral, and in high pH/alkaline conditions, the coral approaches an inert
decoration. The minerals may not completely (or initially) do the job
needed, so some chemicals are used (to prop the kH) but the general
objective is to reach a sustainable chemical-free operation.

Yes and no. On the surface, yes, as every change or risk of

imbalance is
magnified by a greater fishload (smaller tank), and larger tanks

(100g+)
move (parametrically) very slowly, almost establishing their own
biotope-like balance if allowed to, but (there is always a but)....

If
it takes more time to 'affect' a larger tank, they also have much

more
momentum, so that the intitial correctve actions often appears
ineffective. Coupled with the hobbyist's more relaxed approach with
larger tanks (and who can blame us after so many test results appear

so
constant), that we sometimes get caught unawares ;~).


The proper way to approach this large-tank complacency, then, is to
use really precise (and accurate) test kits, and use them frequently.
Key, too, is to produce a log and/or graphical representation of the
parameters. With really fastidious data collection, I think one
stands a better chance of seeing if a smal variation in a test result
is within the "noise" to be expected.


That is one of several ways to achieve good results. Another method is
to very slowly increase your bio-load while monitoring the parameters
less agressively. Another method is to stabilize on a relatively small
(non-breeding) fish-load with a moderately high plant load, whose growth
rate will parallel the fish growth *and* the rate of detritus
accumulation to achieve a balance. Another method is to ignore
parameters and follow an agressive water changing routine. Another
method is an agressive removal of all solid wastes through maintenence
and filtration coupled with a water change routine designed to maintain a
minimum kH. Another is to routinely add something like sodium
bicarbonate to the change water.

A planted soft-water tetra tank lends itself to a combination of the well
planted / low fish-load / low-breeding probability / overfiltered
solution with regular water changes, and monitoring the kH to stay above
a described minimum (using natural modifiers), or using tannic acids
(driftwoods, peat etc) to achieve a simialr stabilization.

Keep in mind that my biased opinions are rooted in
i) I'm lazy, so I'll do lots of front-end research and work to achieve
the lowest possible running maintenence
ii) I want it to look natural, a cross-section of nature
iii) I want to maximize fish health by minimizing water-parameter bounce

[snippety-snip]



snip
If I target a pH of, say, 6 (and my gut feeling is that it can

safely
be done) I'm not too worried about affecting the fishies adversely.
I'll bet that within reason dissolved C02 won't displace dissolved

O2,
and the Cards will be fine.


Yes, I've also read that O2 displacement by CO2 does not

significantly
occur in these applications. If your interest has you curious, would
using a nitrogen/CO2 mix be more advantageous? I wonder what the

plants
would think of that? It would be a more natural mixture (as a ratio

to
CO2, not O2).


First, it would seem that my gut feeling, while technically correct,
would not have left me much wiggle room at all. At pH6, CO2 between
10-25 ppm (18ppm) you need to maintain kH of 0.6 (which I can't get,
even with my water, without diluting with RO). I certainly would NOT
want to play with kH=0.6 water in other than a quite large and
understocked tank.


My understanding is that the chemical properties at work do not strictly
follow the formula. The carbonic-acid induced balance very quickly
normalizes when the CO2 injection is removed, causing the pH to bounce
back to the true equilibrium. The way I look at it, the objective is to
achieve a non-CO2 working balance, and then add CO2 for entertainment
purposes (and achieve your new artificial balance). Achieving a
*working* balance with injected CO2 seems somewhat precarious, and best
left to experienced hobbyists running more than one tank. imo, if you
only have one tank to play with, get your working balance established and
then you can tweak with a bit of CO2 as you become more comfortable with
the processes taking place (just general advice and not particularly
directed at anyone).

Next, as to the idea of using an N2/CO2 mix for carbon dioxide
injection: I can think of a few reasons it mightn't be advantageous at
all. First, the tank water at large is already saturated with N2 from
the air, and available nitrogen *as nitrogen* is not important to a
system where nitrogen fixation is not taking place (e.g.
Rhizobium-using legumes in the terrestrial context). Second, a ten
pound tank of N2/CO2 contains less CO2, and I'd have to change it out
at a faster rate reflecting the proportion less than 100% of CO2 in
the mix.


N2, oh well, it was just an idea ). Thanks for the entertaining,
educational and engaging post Trapper.
cheers
--
www.NetMax.tk

Later, gator!
--Trapper



 




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