help on lowering pH, to save Co2 - The Planted Tank Forum
 
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post #1 of 6 (permalink) Old 06-06-2005, 04:30 PM Thread Starter
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help on lowering pH, to save Co2

right

I'm having trouble adjusting my pH, to a proper level. I've been doing it with Co2, but because my tap water is 8.3, I can run through a 500g bottle in a few weeks... which is a rather expensive venture.
I just tried lowering pH with phosphoric acid, which in the beginning worked fine..for a few hours, then pH started rising again... i guess kH is buffering out..
Sunday:
20:00hrs 7,23pH
21:45hrs 7,30pH
Monday:
8:45hrs 7,53pH
10:49hrs 7,60pH
17:05hrs 7,78pH
18:26hrs 7,86pH

water out of tap:

pH 8,3
kH 6,5
dgH 16-17


what would be the best way for me to adjust my params. so I dont have to fill the pockets of my lfs on a regular basis?
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post #2 of 6 (permalink) Old 06-06-2005, 04:52 PM
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Quote:
Originally Posted by Symbiot
right
I'm having trouble adjusting my pH, to a proper level. I've been doing it with Co2, but because my tap water is 8.3, I can run through a 500g bottle in a few weeks... which is a rather expensive venture.
I just tried lowering pH with phosphoric acid, which in the beginning worked fine..for a few hours, then pH started rising again... i guess kH is buffering out..
How are you getting that CO2 into the the tank?
How big is the tank?
Surface agitation/oxygen via air pump?

Even still a 500g (little over a pound) bottle should last about 2 months.

I don't know what the market is like for re-fillable tanks in Denmark, but I wouldn't doubt there is somewhere that you can lease/rent a 2000kg (Close to 5lb) because I did see the prices, and $110 euros (DKK still around 7.5 on fx market?) is a bit steep. But IIRC, CO2 pollution taxes there are a bit high as well...

You may have a look here:
http://firma.eniro.dk/query?search_w...heading_begin=
and see if any of them can sell/lease on small tanks.


Quote:
Originally Posted by Symbiot
what would be the best way for me to adjust my params. so I dont have to fill the pockets of my lfs on a regular basis?
It depends on why you want to lower your pH. Plants will benefit from the CO2, if you don't have plants, lowering pH is handled a bit differently.


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post #3 of 6 (permalink) Old 06-06-2005, 05:27 PM Thread Starter
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Quote:
Originally Posted by jhoetzl
How are you getting that CO2 into the the tank?
How big is the tank?
Surface agitation/oxygen via air pump?

co2 via pressurized, ph-controlled, Reactor 1000
tank is 86Gallon
surface agitaion minimal, only spraybar. no oxygen..


Even still a 500g (little over a pound) bottle should last about 2 months.

that's what i figured....

I don't know what the market is like for re-fillable tanks in Denmark, but I wouldn't doubt there is somewhere that you can lease/rent a 2000kg (Close to 5lb) because I did see the prices, and $110 euros (DKK still around 7.5 on fx market?) is a bit steep. But IIRC, CO2 pollution taxes there are a bit high as well...

I can lease one somewhere im sure, but lfs' are rather expensive...%#%#


You may have a look here:
http://firma.eniro.dk/query?search_w...heading_begin=
and see if any of them can sell/lease on small tanks.

1 actual welding company came up..rest was names only.. welding=svejse in Danish! =)


It depends on why you want to lower your pH. Plants will benefit from the CO2, if you don't have plants, lowering pH is handled a bit differently.
Of course I want the plants to do as well as possible, so I'm going for approx 30ppm, which i very difficult with my params... unless you use a 500g bottle as fast as me! =)

I'm hoping to come up with a bette solution though....
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post #4 of 6 (permalink) Old 06-06-2005, 05:28 PM Thread Starter
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I'm looking into building a overflow/sump to ease lots of things, but also to add more spaghnum, again to lower pH, and kH.
but that's a completely different thread.
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post #5 of 6 (permalink) Old 06-06-2005, 05:36 PM
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What kind of substrate are you using? Do you have anything in the tank which might be causing your pH to rise - any limestone rocks, for example

You shouldn't measure your pH immediately after coming from the tap. Let it sit overnight, then measure it. I wouldn't recommend using phosphoric acid to lower your pH, because then you can't use the kh/pH table, since the acid is lowering your pH not your CO2.

I have kh of 9.5, and have no problem dropping my pH with CO2. Make sure you have a good reactor and little/none surface agitation to properly dissolve the CO2 and maintain it in solution.

I am not familiar with 500g cylinders/bottles of CO2. But your tank may be large enough to warrant a larger size bottle. My 10 lb cylinder feeds a 29 and a 10 gal tank and lasts for almost a year.

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post #6 of 6 (permalink) Old 06-06-2005, 06:36 PM
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One thing has been overlooked here. If you lower your pH with anything BUT CO2 you are NOT adding CO2 to the water.

If you lower the pH to 6 with the use of acid based buffers and have a kH of 6.5 the pH/kH/CO2 chart will say you have a CO2 level of 195 ppm. But that's not true. You can't get CO2 into the tank with anything but CO2 injection. The use of ANY buffers other than bicarbonate based buffers will destroy the pH/kH/CO2 relationship.

In short the only way to get 30 ppm of CO2 is to inject CO2. I would suggest you find a larger CO2 bottle.
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