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Discussion Starter #1
Hey guys i just added a pressurized CO2 system on my 10 gallon yesterday, and stupid me didnt read the instructions right and kept the co2 running for a few hours which dropped my PH level to 4.6. After reading the instructions, i realized i needed to plug my regulator into my controller so it would shut off if levels were too low. So gradually i added some baking soda and got the PH back up to 7.0 over a few hour span. I just tested my water and it dropped again to 6.8, my GH is at a wopping 16.8 degrees, and my KH is at 2.2 degrees. The co2 hasnt kicked in again since i set it for 7.0 PH. My PH is gradually going down what is causing this to happen??? Should i change the water, leave it alone or do you guys suggest something else? At this rate i'll never get co2 into my aquarium since it wont ever go up to 7.0. Oh and just so everyone knows my water out of the tap is 7.2 PH.

Thanks for any help
 

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There is no reason to maintain a specific pH in a planted tank. CO2 cannot drop the pH too low for the plants or fish, even if the KH is 2 dKH.* But, when you add baking soda to increase the KH, you are messing with the fish's osmotic balance, and that may not be good for them. If you want to use a pH controller, first set the bubble rate so a drop checker tells you you are near the optimum 30-40 ppm of CO2 in the water, then slowly, a little bit each day, increase the bubble rate, until the plants pearl a couple of hours or so after the lights come on, but the fish don't head for the surface and "gasp for air". Now, set the pH controller to control the pH to whatever it is at that bubble rate.

Unfortunately, the bubble rate for optimum CO2 varies depending on how much plant mass you allow to build up, how severely you prune the plants, and how much surface water ripple you maintain. So, in the end, you almost have to tinker with the bubble rate often, to keep the CO2 concentration at the optimum level.

If you drop the light intensity down to moderate to high, instead of high intensity, maintaining the bubble rate at the optimum point isn't nearly as necessary. That lets you enjoy the fish and plants more, and prune and adjust the bubble rate less.

*The reason that CO2 won't drop the pH too low is associated with the solubility of CO2 in water, the mix of carbonic acid, carbonates and dissolved CO2, as the pH drops, as I recall. It has been several months since I picked this up from The Barr Report, and did the calculations to determine the lowest pH that CO2 can drive aquarium water to, so I don't remember the details now.
 

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Discussion Starter #4
thanks for the info guys! Now, what i still dont understand is, why is my PH dropping at 0.1 per 15 minutes? Before i added my Co2, it was a stable 7.6, but last night it went all the way down to about 5.5 then i got concerned and completely shut off the co2 gas, then it leveled off at 4.6. Stupid me added that baking soda which increased the PH back up to 7, but now its losing 0.1 again. The system im using is the aquariumplants.com ultimate system, comes with their regulator, tank, and a rio pump with vortex reactor, and the Milwaukee PH controller. Hoppy im sorry if you answered this question, im still not getting it! LOL im a newbie! :)
 

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thanks for the info guys! Now, what i still dont understand is, why is my PH dropping at 0.1 per 15 minutes? Before i added my Co2, it was a stable 7.6, but last night it went all the way down to about 5.5 then i got concerned and completely shut off the co2 gas, then it leveled off at 4.6. Stupid me added that baking soda which increased the PH back up to 7, but now its losing 0.1 again. The system im using is the aquariumplants.com ultimate system, comes with their regulator, tank, and a rio pump with vortex reactor, and the Milwaukee PH controller. Hoppy im sorry if you answered this question, im still not getting it! LOL im a newbie! :)
When CO2 dissolves into water it forms some carbonic acid, and that acid reduces the water's pH. But, none of our methods for adding CO2 to water acts instantaneously. We bubble the CO2 into the water and the water absorbs a little at a time, until the amount of CO2 being lost from the water surface is the same as the amount being added. At that point the water remains at about the same pH -same amount of carbonic acid in the water - until something changes. When you observe the pH as you add CO2, it will drop continuously and more and more slowly until it is around 1.0 less than when you started, if you end up with about 20-40 ppm of CO2 in the water. This happens whether the KH is 2 degrees or 10 degrees. It happens whether you start at a 8.0 pH or 6.0 pH.

If your pH probe tells you that your tank water is below 5 pH you probably need to recalibrate the probe.
 

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Discussion Starter #6
Thanks im starting to get it a bit now! :) Heres another question for ya, you add CO2 and the PH goes from say 7.2 to 6.2, and your controller is set to 6.2 what makes the PH level go back up? See my CO2 setup has a controller that when you set the PH level you want, it shuts off the CO2 so you dont overdose.
 

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Thanks im starting to get it a bit now! :) Heres another question for ya, you add CO2 and the PH goes from say 7.2 to 6.2, and your controller is set to 6.2 what makes the PH level go back up? See my CO2 setup has a controller that when you set the PH level you want, it shuts off the CO2 so you dont overdose.
That means the CO2 is getting used up and maybe out-gassed. When it reaches a certain high point, the pH controller turns the solenoid back on to allow for more CO2. Then when it reaches your set point, it turns the solenoid off. If your controller is a SMS122 from Milwaukee, it allows for a 0.2 pH change before it turns the solenoid on and off. It doesn't hold a certain pH point like I think that you are thinking. It allows it to vary some which isn't a problem. The Pinpoint controller has a much closer control when it turns the solenoid on and off.

You should do a series of water changes to get the baking soda out. Then use a drop checker with a 4dKH solution to set the set point on your controller.
 

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Discussion Starter #8
Alright, here's where i am at. As of yesterday, im still dosing with ferts, but my CO2 didnt come on at all obviously since i set my controller at 6.5. Left C, im starting to understand a bit more now as i see my controller does allow a 0.2 change. I ordered up a drop checker which wont come in until wednesday unfortunately so, i guess im stuck with this problem for a bit. On the plus side, my fish look happy and are swimming around, my plants aren't dying, and i have no algae for now which is a plus! Thanks guys for the help, any more tips would be great! :)
 

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...So gradually i added some baking soda and got the PH back up to 7.0 over a few hour span. I just tested my water and it dropped again to 6.8, my GH is at a wopping 16.8 degrees, and my KH is at 2.2 degrees. ...
Is this a typo?

Baking soda increases the KH and not the GH.

What is the KH and GH of your change water?

Alright, here's where i am at. As of yesterday, im still dosing with ferts, but my CO2 didnt come on at all obviously since i set my controller at 6.5.
Did you do anything to remove your baking soda that you added? If not, do some water changes to get your KH like your tap water or whatever water that you use for your water changes.

Let's say that the above is a typo. Then, if you have a KH of 16.8 and a pH 6.5, that means that you have dangerously high CO2 levels. If it is not a typo and you do have a KH of 2.2 with a pH of 6.5; your CO2 level is a little low. You can adjust your controller to 6.4 or 6.3.

Left C, im starting to understand a bit more now as i see my controller does allow a 0.2 change.
That's good.

I ordered up a drop checker which wont come in until wednesday unfortunately so, i guess im stuck with this problem for a bit. ...
Did you get the 4 dKH solution with it or is the 4dKH solution already mixed with the Bb indicator solution?
 

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Discussion Starter #10
Ok, unfortunately that wasn't a typo
My GH is really 16.8 degrees (this is using a Hagan master test kit)
My KH is 2.2 degrees
and my PH according to my controller is now at 5.3.

Ive tested my controller twice now with the solution that i have, the 4.01 and the 7.01 solution.

Then i even went further into testing my tap water which is 7.2, and it stayed steady. So i know my controller is working good! :)

I dont know what the KH and GH of my test water is, ill check it tonight, when i do the water change on my tank to get the baking soda out.

As for the 4 dKH solution with my drop checker, thats coming later i purchased one off ebay which won't be here for 2 weeks! So i bought a Red Sea CO2 Indicator off of big als for the time being. It doesn't say if it uses the 4 dKH solution.
 

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Ok, unfortunately that wasn't a typo
My GH is really 16.8 degrees (this is using a Hagan master test kit)
My KH is 2.2 degrees
and my PH according to my controller is now at 5.3.

Ive tested my controller twice now with the solution that i have, the 4.01 and the 7.01 solution.

Then i even went further into testing my tap water which is 7.2, and it stayed steady. So i know my controller is working good! :)

I dont know what the KH and GH of my test water is, ill check it tonight, when i do the water change on my tank to get the baking soda out.

As for the 4 dKH solution with my drop checker, thats coming later i purchased one off ebay which won't be here for 2 weeks! So i bought a Red Sea CO2 Indicator off of big als for the time being. It doesn't say if it uses the 4 dKH solution.
All drop checkers need 4 dKH distilled water in order to indicate when the CO2 concentration is about 30 parts per million. Few makers of drop checkers know that, and most will tell you to use tank water, which is just an inaccurate way to measure the tank pH.

Something is going on with your water. If you really do have the pH down to around 5.3, and the fish are happy, you may have a lot of tannins in the water, or something else driving down the pH. Do you have a lot of "driftwood" in the tank, or "almond leafs", etc.?
 

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...
As for the 4 dKH solution with my drop checker, thats coming later i purchased one off ebay which won't be here for 2 weeks! So i bought a Red Sea CO2 Indicator off of big als for the time being. It doesn't say if it uses the 4 dKH solution.
Unfortunately, the Red Sea product comes with only the Bromothymol blue pH indicator solution. The 4 dKH solution isn't included.

Don't follow the instructions that comes with that drop checker when it says to use aquarium water in it. Follow what Hoppy is telling you.

Some people make their own 4 dKH solutions. I used the method that billionzz posted.
http://www.plantedtank.net/forums/general-planted-tank-discussion/42429-kh-standard-how.html
 

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Discussion Starter #15
Thanks guys, you've been a real help so far!

So whats the best way to get the tannins out of my tank so the PH stabilizes??? The wood didnt stain my water at all, its crystal clear!
 

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Discussion Starter #17
Well i do have the activated carbon in my filter, ill change it out tonight when i do the water change, since its been just over a month
 

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I'm actually getting one of those red sea drop checkers myself, should be arriving tomorrow. I want to make the 4 dKH solution myself, the issue is the scale and graduated cylinders required using that method. Where did you get your scale/etc in order to mix this accurately?
I didn't have a scale that measured to two decimal places when I made my solution. Mine only measured to one decimal place. I have one now that measures to three places. I got my original scale and graduated cylinders from Aquatic Eco-Systems, Inc. There are plenty of scales on ebay. Try to get an accurate set. Some of the really cheap ones may not be very accurate.

Carolina Biological Co has graduated cylinders as well as Cole-Parmer. Their scales are a bit expensive. US Plastics Corp may be cheaper. They have economy to more expensive graduated cylinder in their Lab Section. They don't have any scales though.

I mentioned that my scales measured to one place and that they may of caused me some error. After I made my solution, I checked the KH with my LaMotte test kit. I had 4.26 dKH. That was close enough for me and I used it. It only increased the CO2 level by ~2 ppm at a pH of 6.6 compared to a 4 dKH solution. I could of added a bit more distilled water to get it closer to a KH of 4, but I didn't.

Here are two more hints. Open a new box of baking soda for this. An opened box has probably picked up moisture and your weight won't be correct. Then, measure your various solutions as close as you can.
 

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Discussion Starter #19
Alright guys heres the scoop so far, i did a 50% w/c today, before i did that i let my tap water sit for a bit and tested it.

Here are the readings for my tap water!
PH 7.3
GH 6.7 degrees
KH 3.3 degrees

Before i did the water change, my aquarium PH level was at 5.1, after i did the change it went to 7.0, after 2 and a half hours, it had already dropped to 6.3.

So im thinking of doing another water change wednesday night, see what happens again.
 

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