CO2 Controller and Buffers

[MJB]

I just switched from a timer-based CO2 system to a CO2 controller. I was
getting a wide fluctuation in pH from 7.6 in the AM before the timer started
to 7.0 at the end of the lights-on cycle. Now I'm in the range of 6.9-7.1.

I use RO water and just switched from Kent's RO Right to Seachem's
Equilibrium. I also use Kent's pH Stable. I'd like to keep the tank at
about 6.8. I see that there are buffers available that claim to stabilize
the tank there, but I've not had any experience with them.

I do about a 40% weekly water change and bubble the CO2 at a bubble a
second.

Is the combination of Equilibrium + pH Stable the correct way to go?

[Ron Nelson]

MJB wrote:

> I just switched from a timer-based CO2 system to a CO2 controller. I was
> getting a wide fluctuation in pH from 7.6 in the AM before the timer started
> to 7.0 at the end of the lights-on cycle. Now I'm in the range of 6.9-7.1.
>
> I use RO water and just switched from Kent's RO Right to Seachem's
> Equilibrium. I also use Kent's pH Stable. I'd like to keep the tank at
> about 6.8. I see that there are buffers available that claim to stabilize
> the tank there, but I've not had any experience with them.
>
> I do about a 40% weekly water change and bubble the CO2 at a bubble a
> second.
>
> Is the combination of Equilibrium + pH Stable the correct way to go?
>
>

What is your tap water like? It seems like a lot of work rebuilding RO
unless there is something horribly wrong with your tap...

I'm not well versed in the ways of RO but I have read many times around
here about various PH buffers having phosphates (I personally don't know
if pH Stable is one of them???) and making ph/co2 relationships
inaccurate. Hopefully some more knowledgeable than myself will chime in
and help.

Ron

[MJB]

I originally went to RO because my tap water has a pH of about 7.6. I made
the switch before I put in the CO2. Never considered going back to tap
water.

pH stable claims to not contain phosphates. I do have a history of
higher-than-one-would-expect phosphates. I'll have to do some tests on my
reconstituted RO water and see if that could be the source.

"Ron Nelson" > wrote in message
...
>
> What is your tap water like? It seems like a lot of work rebuilding RO
> unless there is something horribly wrong with your tap...
>
> I'm not well versed in the ways of RO but I have read many times around
> here about various PH buffers having phosphates (I personally don't know
> if pH Stable is one of them???) and making ph/co2 relationships
> inaccurate. Hopefully some more knowledgeable than myself will chime in
> and help.
>
> Ron
>

[MJB]

I originally went to RO because my tap water has a pH of about 7.6. I made
the switch before I put in the CO2. Never considered going back to tap
water.

pH stable claims to not contain phosphates. I do have a history of
higher-than-one-would-expect phosphates. I'll have to do some tests on my
reconstituted RO water and see if that could be the source.

"Ron Nelson" > wrote in message
...
>
> What is your tap water like? It seems like a lot of work rebuilding RO
> unless there is something horribly wrong with your tap...
>
> I'm not well versed in the ways of RO but I have read many times around
> here about various PH buffers having phosphates (I personally don't know
> if pH Stable is one of them???) and making ph/co2 relationships
> inaccurate. Hopefully some more knowledgeable than myself will chime in
> and help.
>
> Ron
>

[Ron Nelson]

MJB wrote:
> I originally went to RO because my tap water has a pH of about 7.6. I made
> the switch before I put in the CO2. Never considered going back to tap
> water.
>
> pH stable claims to not contain phosphates. I do have a history of
> higher-than-one-would-expect phosphates. I'll have to do some tests on my
> reconstituted RO water and see if that could be the source.
>

With the addition of CO2 if your tap PH is 7.6 and your KH is around 3
(guessing) and you set the PH controller around 6.6 to 6.8 you would
have 15-25 ppm of CO2 which is what some of the pro's around here have
recommended for planted tanks in the past.

If you want to see a good table for the PH/KH/CO2 relationship have a
look at http://www.thekrib.com/Plants/CO2/kh-ph-co2-chart.html

Hope this helps,
Ron

[Dave Millman]

MJB wrote:

> I just switched from a timer-based CO2 system to a CO2 controller. I was
> getting a wide fluctuation in pH from 7.6 in the AM before the timer started
> to 7.0 at the end of the lights-on cycle. Now I'm in the range of 6.9-7.1.

My tapwater is nearly identical to yours. I leave the CO2 on 24 hours. The pH
varies less than 0.2 from end of light to end of dark periods.

> I use RO water and just switched from Kent's RO Right to Seachem's
> Equilibrium. I also use Kent's pH Stable.

I also use RO, but am happy with RO Right. pH Stable is 100% baking soda (Sodium
bicarbonate). Most of using RO buffer with Sodium bicarbonate, but use the
cheaper Arm & Hammer brand from the supermarket! True confessions: I did buy one
jar of pH Stable before confirming it was baking soda.

> I'd like to keep the tank at
> about 6.8. I see that there are buffers available that claim to stabilize
> the tank there, but I've not had any experience with them.

Do yourself a favor and keep it that way. Set your KH with baking soda,
measuring carefully for the first few weeks to figure out the right amount to
add with a given weekly water change. Then target 20-25ppm CO2, and set the pH
controller to achieve that.

Or return the pH controller and set your bubble rate to do the same thing, 24hrs
per day. Works for me.

In any case, targeting pH is not the right way to think about it in a plant
tank. You want to set your KH, then target a CO2 concentration, which is in turn
measured by your pH. I set my KH at 3, which requires 1 teaspoon of baking soda
in a 30 gallon weekly water change. Then I adjust the needle valve to get 25 ppm
CO2, which I calculate by measuring pH at 6.6 and reading the chart at
http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

[gizmo]

Why does it important to keep PH levels at about 6.8 ?
"Dave Millman" > wrote in message
...
> MJB wrote:
>
> > I just switched from a timer-based CO2 system to a CO2 controller. I
was
> > getting a wide fluctuation in pH from 7.6 in the AM before the timer
started
> > to 7.0 at the end of the lights-on cycle. Now I'm in the range of
6.9-7.1.
>
> My tapwater is nearly identical to yours. I leave the CO2 on 24 hours. The
pH
> varies less than 0.2 from end of light to end of dark periods.
>
> > I use RO water and just switched from Kent's RO Right to Seachem's
> > Equilibrium. I also use Kent's pH Stable.
>
> I also use RO, but am happy with RO Right. pH Stable is 100% baking soda
(Sodium
> bicarbonate). Most of using RO buffer with Sodium bicarbonate, but use the
> cheaper Arm & Hammer brand from the supermarket! True confessions: I did
buy one
> jar of pH Stable before confirming it was baking soda.
>
> > I'd like to keep the tank at
> > about 6.8. I see that there are buffers available that claim to
stabilize
> > the tank there, but I've not had any experience with them.
>
> Do yourself a favor and keep it that way. Set your KH with baking soda,
> measuring carefully for the first few weeks to figure out the right amount
to
> add with a given weekly water change. Then target 20-25ppm CO2, and set
the pH
> controller to achieve that.
>
> Or return the pH controller and set your bubble rate to do the same thing,
24hrs
> per day. Works for me.
>
> In any case, targeting pH is not the right way to think about it in a
plant
> tank. You want to set your KH, then target a CO2 concentration, which is
in turn
> measured by your pH. I set my KH at 3, which requires 1 teaspoon of baking
soda
> in a 30 gallon weekly water change. Then I adjust the needle valve to get
25 ppm
> CO2, which I calculate by measuring pH at 6.6 and reading the chart at
> http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm
>
>
>

[Alex R]

"MJB" > wrote in message
. net...
> I originally went to RO because my tap water has a pH of about 7.6. I
made
> the switch before I put in the CO2. Never considered going back to tap
> water.

If your pH is only 7.6, then your KH is about 4-5 degrees, not terribly
hard. As others have pointed out, you should only use CO2 to lower the pH.
In addition, reconstituted RO water is not as good for plants as tap water
of the same hardness. It would statistically have a greater variety of trace
elements and good amounts of both Ca & Mg, which plants like in high
quantities. I don't see any reason why you should spend the extra effort on
RO anymore. You can easily maintain a 6.8 pH with CO2. Don't add any buffers
because they'll throw off your CO2 calculations and defeat the function of
CO2 of reducing your pH.

> pH stable claims to not contain phosphates. I do have a history of
> higher-than-one-would-expect phosphates.

That's good. Plants like PO4.
__
Alex
pcalex (at) hotpop.com