CO2 vs. low kH...a losing battle??? - Aquarium Advice

fishluvr · 01-19-2004, 08:40 PM

I seem to have a small problem...

I'm running a pressurized [acronym:ec66fb6f1f="Carbon dioxide"]CO2[/acronym:ec66fb6f1f] system on a 120 [acronym:ec66fb6f1f="Gallon"]gal[/acronym:ec66fb6f1f] tank and my pH refuses to drop below 7.2 (according to my Milwaukee SMS122 controller). As soon as the lights come on, my pH begins to rise at a rate of about 0.1 per hour, until it gets back up to about 7.6 (where it was before I added the [acronym:ec66fb6f1f="Carbon dioxide"]CO2[/acronym:ec66fb6f1f] on Saturday).

I'm running 3.2 [acronym:ec66fb6f1f="Watts Per Gallon"]wpg[/acronym:ec66fb6f1f] (384 watts) for 5 hours, off 2 hours, then on another 6. My [acronym:ec66fb6f1f="Carbon dioxide"]CO2[/acronym:ec66fb6f1f] is set to bubble about every 2 secs now (started at every 6 secs)...

I've tried several test kits to verify my data, but so far, it's looking like there may be something wrong with my controller.

These are from a control sample of my tank...
Kit 1 shows: pH 6.8*, Nitrate <10ppm, Nitrite 0ppm, gH 75ppm, kH ~40ppm

Other tests show: pH 7.0 , kH ~2dkH

SMS122: after calibration (with 7 and 4 solutions) showed pH 7.6

*Kit 1 has registered pH at 6.8 on every test, incliding with the bottle of 7.01 I've got, so I don't trust that reading...

Does anyone have any idea what could be holding the pH at 7.2? I will be trying to find out what my local water conditions are from the local sanitary commission...

_Nemo_ · 01-19-2004, 10:14 PM

You need to bring your [acronym:fc55c77ae2="Degrees of carbonate hardness"]dkH[/acronym:fc55c77ae2] to about 6 [acronym:fc55c77ae2="In my opinion"]IMO[/acronym:fc55c77ae2]. You can use plain baking soda to do it but that will bring up your pH. You have to dose then a lot more to bring the pH down to where you want it to be - but it will be stable at that level then.

Keep notes of what you have added - it is a trial and error exercise. Hope you have no fish in this tank

.

betowess · 01-20-2004, 02:51 AM

Yeah, at 2 dKH you may see wide [acronym:1da30803da="power head or Measure of the concentration of hydrogen ions, depending on context"]PH[/acronym:1da30803da] shifts. I agree you need more [acronym:1da30803da="Carbonate Hardness"]KH[/acronym:1da30803da] buffer and the [acronym:1da30803da="Carbon dioxide"]CO2[/acronym:1da30803da] [acronym:1da30803da="Parts per Million"]ppm[/acronym:1da30803da] will come up and the [acronym:1da30803da="power head or Measure of the concentration of hydrogen ions, depending on context"]PH[/acronym:1da30803da] should drop. I think. As you probably know its normal for [acronym:1da30803da="power head or Measure of the concentration of hydrogen ions, depending on context"]PH[/acronym:1da30803da] to rise when the sun is out. Good luck.

01-20-2004, 08:24 AM

You should raise the kH a bit. But with the controller it's not as critical. And if your controller is calibrated then I would trust it over the test kits. And for a 120 gallon tank your [acronym:298c2cbbb2="Carbon dioxide"]CO2[/acronym:298c2cbbb2] injection rate sounds very, very low. I would start by increasing the bubble rate to at least 100 bpm. You have the controller you don't have to worry about getting too much [acronym:298c2cbbb2="Carbon dioxide"]CO2[/acronym:298c2cbbb2] into the tank. In fact to get decent [acronym:298c2cbbb2="Carbon dioxide"]CO2[/acronym:298c2cbbb2] levels you would have to get your pH down to 6.4 with your current kH. So you might want to increase your kH.

fishluvr · 01-20-2004, 11:35 PM

Thanks, all..Right after posting I started thinking about going with the inreased [acronym:a0d547cefc="Carbon dioxide"]CO2[/acronym:a0d547cefc] flow due to the tank size, and just letting the controller take it from there, but I didn't really trust my instinct on it...

Since I do have some fish in there, I set the controller at 7.4 and turned the bubble rate to about 70 bpm...the tank seems to have stabilized, and I've slightly increased the bubble rate again (to just over 100 bpm...seems to be much closer to what I need...thanks, Rex) and I've lowered the setting to 7.3...I plan on continuing this 0.1 pH change every couple of days until I get down to about 6.8 or so...

Thanks again to all...

01-19-2004, 08:40 PM	#1
fishluvr Aquarium Advice Apprentice Join Date: Nov 2003 Location: Maryland Posts: 25 Images: 4	CO2 vs. low kH...a losing battle??? I seem to have a small problem... I'm running a pressurized [acronym:ec66fb6f1f="Carbon dioxide"]CO2[/acronym:ec66fb6f1f] system on a 120 [acronym:ec66fb6f1f="Gallon"]gal[/acronym:ec66fb6f1f] tank and my pH refuses to drop below 7.2 (according to my Milwaukee SMS122 controller). As soon as the lights come on, my pH begins to rise at a rate of about 0.1 per hour, until it gets back up to about 7.6 (where it was before I added the [acronym:ec66fb6f1f="Carbon dioxide"]CO2[/acronym:ec66fb6f1f] on Saturday). I'm running 3.2 [acronym:ec66fb6f1f="Watts Per Gallon"]wpg[/acronym:ec66fb6f1f] (384 watts) for 5 hours, off 2 hours, then on another 6. My [acronym:ec66fb6f1f="Carbon dioxide"]CO2[/acronym:ec66fb6f1f] is set to bubble about every 2 secs now (started at every 6 secs)... I've tried several test kits to verify my data, but so far, it's looking like there may be something wrong with my controller. These are from a control sample of my tank... Kit 1 shows: pH 6.8, Nitrate <10ppm, Nitrite 0ppm, gH 75ppm, kH ~40ppm Other tests show: pH 7.0 , kH ~2dkH SMS122: after calibration (with 7 and 4 solutions) showed pH 7.6 Kit 1 has registered pH at 6.8 on every test, incliding with the bottle of 7.01 I've got, so I don't trust that reading... Does anyone have any idea what could be holding the pH at 7.2? I will be trying to find out what my local water conditions are from the local sanitary commission...

01-20-2004, 02:51 AM	#3
betowess Aquarium Advice Freak Join Date: Aug 2003 Location: Washington State,USA Posts: 389 Images: 3	Yeah, at 2 dKH you may see wide [acronym:1da30803da="power head or Measure of the concentration of hydrogen ions, depending on context"]PH[/acronym:1da30803da] shifts. I agree you need more [acronym:1da30803da="Carbonate Hardness"]KH[/acronym:1da30803da] buffer and the [acronym:1da30803da="Carbon dioxide"]CO2[/acronym:1da30803da] [acronym:1da30803da="Parts per Million"]ppm[/acronym:1da30803da] will come up and the [acronym:1da30803da="power head or Measure of the concentration of hydrogen ions, depending on context"]PH[/acronym:1da30803da] should drop. I think. As you probably know its normal for [acronym:1da30803da="power head or Measure of the concentration of hydrogen ions, depending on context"]PH[/acronym:1da30803da] to rise when the sun is out. Good luck. __________________ 26 Gallon Planted Community, 90 Gallon Planted Community - Rena XP3, XP2 Filters, Pressurized[acronym:c235e7f258="Carbon dioxide"]CO2[/acronym:c235e7f258], Eco or Flourite, TEK 4x54 T5 light, AH Supply [acronym:c235e7f258="Power compact fluorescent"]PC[/acronym:c235e7f258] s

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01-19-2004, 10:14 PM	#2
_Nemo_ Aquarium Advice Apprentice Join Date: Jan 2004 Location: Ottawa, Ontario, Canada Posts: 43	You need to bring your [acronym:fc55c77ae2="Degrees of carbonate hardness"]dkH[/acronym:fc55c77ae2] to about 6 [acronym:fc55c77ae2="In my opinion"]IMO[/acronym:fc55c77ae2]. You can use plain baking soda to do it but that will bring up your pH. You have to dose then a lot more to bring the pH down to where you want it to be - but it will be stable at that level then. Keep notes of what you have added - it is a trial and error exercise. Hope you have no fish in this tank .

01-20-2004, 08:24 AM	#4
Guest Posts: n/a	You should raise the kH a bit. But with the controller it's not as critical. And if your controller is calibrated then I would trust it over the test kits. And for a 120 gallon tank your [acronym:298c2cbbb2="Carbon dioxide"]CO2[/acronym:298c2cbbb2] injection rate sounds very, very low. I would start by increasing the bubble rate to at least 100 bpm. You have the controller you don't have to worry about getting too much [acronym:298c2cbbb2="Carbon dioxide"]CO2[/acronym:298c2cbbb2] into the tank. In fact to get decent [acronym:298c2cbbb2="Carbon dioxide"]CO2[/acronym:298c2cbbb2] levels you would have to get your pH down to 6.4 with your current kH. So you might want to increase your kH.

01-20-2004, 11:35 PM	#5
fishluvr Aquarium Advice Apprentice Join Date: Nov 2003 Location: Maryland Posts: 25 Images: 4	Thanks, all..Right after posting I started thinking about going with the inreased [acronym:a0d547cefc="Carbon dioxide"]CO2[/acronym:a0d547cefc] flow due to the tank size, and just letting the controller take it from there, but I didn't really trust my instinct on it... Since I do have some fish in there, I set the controller at 7.4 and turned the bubble rate to about 70 bpm...the tank seems to have stabilized, and I've slightly increased the bubble rate again (to just over 100 bpm...seems to be much closer to what I need...thanks, Rex) and I've lowered the setting to 7.3...I plan on continuing this 0.1 pH change every couple of days until I get down to about 6.8 or so... Thanks again to all...