Started DIY CO2, Ph has dropped. Stop CO2 or add baking soda? - The Planted Tank Forum
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post #1 of 24 (permalink) Old 11-29-2005, 10:27 AM Thread Starter
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Started DIY CO2, Ph has dropped. Stop CO2 or add baking soda?

Hi,

I recently started adding DIY CO2 to my tank. My plants seem to have picked up pretty well and I seem to have gotten rid of my cloudy water since I started adding CO2.

My only concern now is that my Ph has dropped and I've lost a couple of fish.

My tank parameters are:

Temp: 25C
Ph: 6.4 or 6.6
Ammonia & Nitrite: 0
Nitrate: somewhere between 0 and 5.0.
GH & KH - I'm new to this test and 3 drops seemed to change the water to the colours mentioned in the instructions (looking straight down the tube).

Out of the tap, my water Ph is 7.2 and I've tested water that has stood for a day or so and the Ph is around 7.0 or even 7.2.

I've got a couple of pieces of driftwood in the tank that have been there for about 3 months. I know they may drop the Ph a little but I used to see 7.0 or 6.8 before the DIY CO2.

Should I stop the CO2 and let the Ph come back up or is there something else I need to do? I've read elsewhere on the forum about adding baking soda? How does this help?

Thanks in advance

Chris
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post #2 of 24 (permalink) Old 11-29-2005, 12:07 PM
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Three drops on the test tells us nothing without knowing which test it is.

Normally you would give us the kH either in ppm or degrees.

Some tests are made so that each drop equals 1° and others are made so that each drop equals 10 ppm. Now seeing as how there are ~17.9 ppm in each 1° you can see the problem. We have to guess if you have around 30 ppm which would be a low kH or around 3° which is a borderline kH.

Also without knowing the kH we are unable to determine the CO2 levels.

If the pH is 6.4 and the kH is 3° then the CO2 level is 36 ppm which should not cause any fish deaths.

If the pH is 6.6 and the kH is 3° then the CO2 level is 23 ppm which should not cause any fish deaths.

If the pH is 6.4 and the kH is 30 ppm then the CO2 level is 20 ppm which should not cause any fish deaths.

If the pH is 6.6 and the kH is 30 ppm then the CO2 level is 13 ppm which should not cause any fish deaths.

So based on the scanty information you have given us I doubt that the CO2 is the problem at all.
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post #3 of 24 (permalink) Old 11-29-2005, 12:12 PM
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Chris, are you using the Aquarium Pharmaceuticals test kit? If so (anyone please correct if I am wrong), your KH is right about borderline for swings (3 deg.). Adding CO2 in general will cause a pH drop. Adding baking soda will raise your kH, but I suggest you take a look at Rexx’s site about “Chasing the dragon”, and keep that in mind.


BTW, Rexx, looks like you beat me to the punch.

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Last edited by tazcrash69; 11-29-2005 at 05:07 PM. Reason: typo fix
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post #4 of 24 (permalink) Old 11-29-2005, 04:00 PM
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As I understand it, couldn't a swift drop in pH do the killing?

What kind of fish were lost??

Also, how are you dissolving the co2?
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post #5 of 24 (permalink) Old 11-29-2005, 05:26 PM
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Quote:
Originally Posted by esarkipato
As I understand it, couldn't a swift drop in pH do the killing?
not if the drop in pH was due to co2 injection (unless of course the co2 levels were excessively high... but pH is just the indicator in this case, not the cause).

changes in pH due to alkalinity (KH) can cause illness and/or death.

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post #6 of 24 (permalink) Old 11-30-2005, 01:54 AM Thread Starter
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Quote:
Originally Posted by tazcrash69
Chris, are you using the Aquarium Pharmaceuticals test kit?
Yes I am. Like I said, I'm new to this test. Apologies if the information is considered "scanty".

I'll redo and post more information this evening.

Quote:
Originally Posted by esarkipato
What kind of fish were lost??
Mainly neon and black neon tetra.
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post #7 of 24 (permalink) Old 11-30-2005, 01:57 AM Thread Starter
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Quote:
Originally Posted by esarkipato
Also, how are you dissolving the co2?
Sorry, missed this question in my other post. The CO2 is going through the Nutrafin/Hagen CO2 Ladder.
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post #8 of 24 (permalink) Old 11-30-2005, 08:56 AM Thread Starter
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Question

OK,

I've retested my water this evening.

Ph appears to be back at about 6.8
Gh & Kh both took 6 drops to change colour.

I'm using the Aquarium Pharm test kit so 1 drop = 1 °dGH/°dKH and the sheet that comes with the kit shows this to be 100ppm.

Looking at the chart here:

https://www.plantedtank.net/forums/sh...ad.php?t=23531

My levels are in the yellow even with the lower Ph of 6.4 and Kh reading. I'm also in the yellow with the higher Ph and Kh.

My initial concern when I started this post was that the Ph drop could be the result of the fish loss. This has been suggested to me in other forums.

What I don't understand now is why my Ph is on the up again and my Gh and Kh appear to have doubled. I'm new to the Gh/Kh test so perhaps I didn't add enough drops first time round or I've over done this time?

The DIY CO2 has been running for about 2 weeks so perhaps the CO2 is dropping off? Bubble rate still appears to be the same as before.

Please let me know if I can provide more info?

Cheers,

Chris
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post #9 of 24 (permalink) Old 11-30-2005, 12:37 PM
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You need to stick with one unit of measurement and stay with it. Either say you have 6° of kH like you should have, and throw the chart away, or say you have 100 ppm.

I had to read though your last post a couple of times in this early morning state to figure out what your kH really is.

Now as to why the kH is going up. It's possible you did not correctly do the test the first time. But the AP kH test kit is pretty easy to use unless you are color blind. It's possible that something in the tank is raising the kH.

What is the kH of your source water?
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post #10 of 24 (permalink) Old 11-30-2005, 06:57 PM Thread Starter
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Quote:
Originally Posted by Rex Grigg
You need to stick with one unit of measurement and stay with it. Either say you have 6° of kH like you should have, and throw the chart away, or say you have 100 ppm.
Rex, I'm simply quoting the paperwork that comes with the test kit. This states:

"6° - 11° (100-200ppm) Most tropical fish including angelfish, cichlids, tetras, botia, live plants."

I appreciate your input but I just don't seem to be able to please you. First off your criticise the first post as "scanty". Now I post more info and restate what is in the test kit documentation and this isn't good enough either.

I'll test my source water this evening. I'll ask my wife to double check that so you can insult her too whilst we're at it?
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post #11 of 24 (permalink) Old 11-30-2005, 08:18 PM
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OK, make sure you use the cap when you shake the tube bewtween drops. I know oils can effect pH readings, not sure about kH, but why take a chance.
I know it's a pain (I do it every other day right now), but it eliminates possible outside influences.

Don't take Rexx too hard, he is after all a self declared Curmudgeon
Just trying to get some consistant info.
I've seen posts that say they have 100 degrees and 6 ppm kH.

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post #12 of 24 (permalink) Old 11-30-2005, 09:57 PM Thread Starter
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Quote:
Originally Posted by tazcrash69
OK, make sure you use the cap when you shake the tube bewtween drops. I know oils can effect pH readings, not sure about kH, but why take a chance.
I do cap it as I don't want any of the test kit stuff on my skin never mind influence any test results. I've got two young children and don't want them coming into contact with the stuff because I've got it on me.

Quote:
Originally Posted by tazcrash69
Don't take Rexx too hard, he is after all a self declared Curmudgeon
Just trying to get some consistant info.
I've seen posts that say they have 100 degrees and 6 ppm kH.
Like I said before, I appreciate his input but there are nicer ways of putting what is being said. I've said I'm new to this and I'm looking for help. Sort of makes me regret putting the question out there.
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post #13 of 24 (permalink) Old 12-05-2005, 09:24 AM Thread Starter
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OK, apologies for the delay; not been well.

From the tap, the tests show:

Gh = 6 drops or 6 °dGH. The conversion chart with the test kit says this is 107.4 ppm GH.

Kh = 4 drops of 4 °dKH. The conversion chart with the test kit says this is 71.6 ppm KH.

Can I provide any further information for anyone to assist?

Thanks in advance.

Chris
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post #14 of 24 (permalink) Old 12-05-2005, 12:36 PM
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If your tap water has a kH of 4° then your tap water pH should be around 7.6° after it has rested.

One trick is to double the size of the water sample and then each drop will be equal to 0.5°. The nature of those kits can be a bit difficult. Your water could have a kH of 3.12° but the test kit would show that as 4° as 3 drops will not change the color but 4 will.
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post #15 of 24 (permalink) Old 12-05-2005, 11:34 PM
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If your test numbers are right, the short answer is that you've got too much CO2 in your tank, which is dropping the pH and is probably somewhat toxic even without the lowered pH causing additional stress.

You say your tap water is KH 4, your tank is KH 6, and the low pH you observed was 6.4. From the chart, it looks like you had up to 50 - 75 ppm of CO2 in your tank, which is definitely too much.

What volume is your tank? Maybe you'd be better off with a bigger one!

Or a smaller yeast reactor... You can also add a pinch of baking soda to your yeast / sugar mix to make it go slower, but for a longer period of time.

Another possibility is contamination from the yeast reactor. If the yeast has been going for a while, there's a good bit of alcohol in there, and if the reactor is frothing up and overflowing into the tank at all, that could be another problem. Don't fill your reactor too close to the top when you make the yeast / sugar mix.

Baking soda (sodium bicarbonate, Na.HCO3) increases your KH. KH test kits measure how hard it is to drop the pH of your water. More drops means it takes more acid to reach a low pH. CO2 is an acid when you put it in your tank, so having a higher KH will prevent reasonable amounts of CO2 from dropping your pH off the chart.

Another way of looking at this is that the pH in your tank is determined by the balance of carbonate and carbonic acid (CO2 + water). Baking soda adds carbonate.

GH is a measure of the magnesium and calcium in your water. Those have no effect on pH, so don't worry about it in the context of this problem.

Get familiar with your KH kit until you're confident with your ability to get consistent results, and then keep your KH where you want it by adding baking soda. Don't go nuts - I recommend boosting your tap water by a maximum of 4 KH. If you need to go higher, you'll turn to other carbonates.

1/4 tsp will raise 50 liters by ~1 degree KH. Just add the desired amount at every partial change. eg. if you change 50 l at a time, and you want to go from KH 2 to KH 4, add 1/2 tsp. at each change. Dissolve it in 500 ml of water and pour it slowly into the tank. I don't consider this 'chasing the dragon' any more than adding CO2, or adding some salt to a brackish tank. Carbonates are the buffers that are in natural waters, so you're not creating some artificial system with a bunch of side effects.
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