Hopefully someone can help me here :-)

Recently I moved house and was forced to rebuild my 55 gal (48"x20"x14")
tank from scratch. It's a community tank, which until I moved had very
happy plants which were often pearling streams of bubbles during the day
when the lights were on.

Since moving, the plants are decidedly unhappy and there is some algae
growth (but not too bad) on leaves.

Lighting is flourescent - 1 x 36W 7500K + 1 x 36W 50/50 6000K/Actinic. On
around 10 hours a day.

Tank chemistry at the moment is as follows:

pH 7.2
kH 1-2 deg
Nitrate: 20ppm
PO4: Unknown

From the pH and kH I believe the dissolved CO2 is probably around 2.8ppm
which seems very low.

Problem is, if I attempt to increase the kH, the pH follows it, so I'm
unable to increase kH to increase CO2 concentration. I've never needed to
add CO2 with a reactor before, so there must be something else I missing.

The tank is dosed with Sera Florena fertilizer every couple of weeks.

Anyone have any suggestions about how I may improve the water chemistry to
get the plants in action again?

The fish are all perfectly happy BTW.


Thanks
Graham.

"Graham Broadbridge" wrote
Anyone have any suggestions about how I may improve the water chemistry to
get the plants in action again

How old are your lights?
I had some issues a few weeks back with slower growth & BGA.
I replaced a tube that was only 9 months old & now all is OK.

--
Graham Ramsay
Blairgowrie (UK)
www.ibrox.freeserve.co.uk/aquarium.htm

Xref: 127.0.0.1 rec.aquaria.freshwater.plants:72925

Both tubes are less than three months old.

It's something in the chemistry - times like this I wish I'd listened more
in Chem classes at school

Thanks for the suggestion, though.

Graham.


"Graham Ramsay" wrote in message
...
"Graham Broadbridge" wrote
Anyone have any suggestions about how I may improve the water chemistry
to
get the plants in action again

How old are your lights?
I had some issues a few weeks back with slower growth & BGA.
I replaced a tube that was only 9 months old & now all is OK.

--
Graham Ramsay
Blairgowrie (UK)
www.ibrox.freeserve.co.uk/aquarium.htm

Graham Broadbridge graham at peachy dot org wrote:
tank from scratch. It's a community tank, which until I moved had very
happy plants which were often pearling streams of bubbles during the day
when the lights were on.
snip
unable to increase kH to increase CO2 concentration. I've never needed to
add CO2 with a reactor before, so there must be something else I missing.

You had pearling without added CO2 and with less than 2 watts per gallon?
How is that possible?

How far away did you move? Are you in a different water supply? I bet it's
something in the new water.

--
Victor M. Martinez

http://www.che.utexas.edu/~martiv

Xref: 127.0.0.1 rec.aquaria.freshwater.plants:72945

Hi Victor,

"Victor M. Martinez" wrote in message
...
Graham Broadbridge graham at peachy dot org wrote:
tank from scratch. It's a community tank, which until I moved had very
happy plants which were often pearling streams of bubbles during the day
when the lights were on.
snip
unable to increase kH to increase CO2 concentration. I've never needed
to
add CO2 with a reactor before, so there must be something else I missing.

You had pearling without added CO2 and with less than 2 watts per gallon?
How is that possible?

Dunno, it was as I said before I moved.

How far away did you move? Are you in a different water supply? I bet it's
something in the new water.

Moved less than 5 miles. You're probably right about it being something
lacking in the water.
My first thought was PO4, but prior to the move I always had kH around 5 out
of the tap,
so maybe the soft water is contributing.

I'm no chemist, which is why I posted all the relevant water chemistry.
Maybe someone can explain how I can increase the kH without the pH going
through the roof and killing all the fish. I'm acceptable to all
suggestions.

Regards
Graham


--
Victor M. Martinez

http://www.che.utexas.edu/~martiv

The only way you will be able to increase the KH and lower the pH is by injecting CO2. For example, if you start out with a KH of 4 degrees, your target pH will be around 6.9, giving you an optimum level of CO2 @15ppm, ideal for plants and safe for fish.

The KH can be raised by using baking soda. There is a direct correlation between pH, KH and CO2. When you raise KH, so pH elevates, it's unavoidable, you must use CO2 to lower it!

If CO2 is to low, the plants will eat the KH and convert it to CO2, this process is known as biogenic decalcification, this causes pH to rise and eventually become unstable leading to pH swings.

Best to use a pressurized CO2 system for absolute control.

"Graham Broadbridge" graham at peachy dot org wrote in message . au...

I'm no chemist, which is why I posted all the relevant water chemistry.

Regards
Graham

Think of it like a balance, see saw etc. The CO2 is the acid and the
HCO3(KH) is the base. The pH is a ratio of both of these.
The CO2 is a gas and has an atmospheric component. The KH(HCO3) does
not. Therefore the CO2 can leak(be driven off if in excess) out or
leak into the tank(If the CO2 level is understaturated or you add CO2
to enrich your tank). The KH stays the same pretty much unless you
have a relatively few number of plants that can rip the CO2 out of
HCO3= CO2+OH.

You can get confused by the chemistry and theory or you can just
follwo the pH/KH/CO2 table.

Step one:
Measure KH, make sure it's around 3 degrees(~50ppm) or higher.

Step two:

Find the KH you measured and then find the right pH range for a CO2
level of 20-30ppm range on the pH/KH/CO2 chart

Step three add enough CO2 gas ONLY to achieve this pH.

That's it. Try and maintain the pH in that range while the lights are
on.

Maybe someone can explain how I can increase the kH without the pH going
through the roof and killing all the fish. I'm acceptable to all
suggestions.

Well fish live in nature seem to do fine with good sized swings in
areas with high plant denisities. They are not sudden and take most of
the day to slowly ebb and flow diurnally. Most productive systems do
this, some up to 2 full pH units and some shallow lakes with lots of
plants will go from pH 6 to a pH of 10 daily.

But keeping a certain pH locked in is just to supply the right amount
of CO2 for the plants. This is the name of the game, we don't add CO2
to adjust the pH, just supply the plants with CO2. Some seem to think
plants like a certain pH or KH, which is generally not true. All the
plants want is CO2/nutrients etc.

Regards,
Tom Barr

Hi Tom,

Thanks for the very informative post. Also, thanks everyone else for the
info you have provided.

Over the last 4 days I've introduced some CO2 injection into the tank using
the old 2 litre coke bottle, sugar and yeast mix to generate CO2, and
disolving it into the water using a home built contraption that is
constructed from an old aquarium vaccum cleaner tube fed from the output of
a powerhead with an airstone inside :-)

pH changes were very slow, but at this point I've increased kH from around
1.5 to 4.0 (by addition of baking soda in small steps) in order to maintain
pH 7.0. I've noticed one teaspoon of baking soda increases kH by 1 deg in
my 55 gal tank. pH is currently 7.0 which I believe is around 12ppm CO2 .
Tomorrow I'm expecting a CO2 test kit which will hopefully confirm that
calculation. In any case the fish are all happy and some plants are now
sending strings of bubbles and are showing some new growth.

I believe I understand now the reason why I was able to have a kH reading of
5 deg with a pH of 7.0 without CO2 injection before I moved house. The old
tank was very old, and had been at some time or another either acid or
alkaline so in each case I either added pH-UP or pH-DOWN. After a lot of
reading over the last few days, it seems to me that if one adds a strong
Carbonate buffer (such as pH up) and then adds a strong Phosphate buffer (pH
down), the two will reach an equilibrium in terms of pH, whilst still
maintaining some buffering capacity. Over a period of years this could add
up to a lot of buffering, which is probably what I was seeing with my kH 5
pH 7 reading. Obviously some of each would be lost during water changes,
but the equilibrium would be maintained until such time as the tank crashed
out.

That's my theory, and I'd appreciate any comments.

Regards
Graham.




" wrote in message
om...
"Graham Broadbridge" graham at peachy dot org wrote in message
. au...

I'm no chemist, which is why I posted all the relevant water chemistry.

Regards
Graham

Think of it like a balance, see saw etc. The CO2 is the acid and the
HCO3(KH) is the base. The pH is a ratio of both of these.
The CO2 is a gas and has an atmospheric component. The KH(HCO3) does
not. Therefore the CO2 can leak(be driven off if in excess) out or
leak into the tank(If the CO2 level is understaturated or you add CO2
to enrich your tank). The KH stays the same pretty much unless you
have a relatively few number of plants that can rip the CO2 out of
HCO3= CO2+OH.

You can get confused by the chemistry and theory or you can just
follwo the pH/KH/CO2 table.

Step one:
Measure KH, make sure it's around 3 degrees(~50ppm) or higher.

Step two:

Find the KH you measured and then find the right pH range for a CO2
level of 20-30ppm range on the pH/KH/CO2 chart

Step three add enough CO2 gas ONLY to achieve this pH.

That's it. Try and maintain the pH in that range while the lights are
on.

Maybe someone can explain how I can increase the kH without the pH going
through the roof and killing all the fish. I'm acceptable to all
suggestions.

Well fish live in nature seem to do fine with good sized swings in
areas with high plant denisities. They are not sudden and take most of
the day to slowly ebb and flow diurnally. Most productive systems do
this, some up to 2 full pH units and some shallow lakes with lots of
plants will go from pH 6 to a pH of 10 daily.

But keeping a certain pH locked in is just to supply the right amount
of CO2 for the plants. This is the name of the game, we don't add CO2
to adjust the pH, just supply the plants with CO2. Some seem to think
plants like a certain pH or KH, which is generally not true. All the
plants want is CO2/nutrients etc.

Regards,
Tom Barr