is adding CO2 causing my pH to drop?

[Innivus]

Before I begin, I'm going to politely ask all the chemistry people out there to bring it down to a very simple yes or no question. I read the sticky on the subject - the headache is just starting to go away.

I started adding CO2 (flourish liquid CO2) to reduce some blackbeard algae. But the plants seemed to have gotten worse - I think this is a reflection of the 6.0-ish pH that I'm somehow achieved, but have no idea how (I have 1/3 tank with plant substrate, a medium sized piece of driftwood...those are the only things that I can think of that would lower it that drastically). I'd always thought the pH out of my tap was a bit low (6.5-ish), but I have a QT that I've been keeping, and that's around 7.

So if it is the CO2 lowering the pH, is there a good solution to balance this all out? I've added a bit of crushed coral, but it seems a bit redundant, like opening a window in the winter because you've turned the heat on too high.

Thanks for any thoughts, and remember I'm an English teacher, so any comments invoking the wonders of ions or acid-base neutron exchanges will simply go far over my head. :-)

[mattg]

i Never checked if excel was acidic but it could possibly be, but anyhow heres the usual solution to co2:

Water agitation will release co2 back into the air like an airstone or letting the water level drop some and having a powerfilter make a "waterfall".



Edit: Just did a little experiment and yes the seachem flourish excel is acidic .

[Larry Bugg]

Straight from Seachem...."Flourish Excel will not effect the pH of your tank."

[Sharkbait]

Flourish Excel is NOT 'carbon dioxide.' It is essentially a carbon supplement. In order to have carbon dioxide in your tank, you would need either a DIY CO2 setup or a pressurized setup. And yes, actual CO2 will cause your PH to drop.

Flourish Excel is great at getting rid of BBA - as I just had an outbreak recently. Dosing at 1 cap per 10 gallons for 14 days really made a difference. Now it was just important to get faster growing plants (stem plants) to take hold so algae wouldn't.

Is your driftwood new? If so, it will have an effect on your PH, bringing it down.

You can add the crushed coral to the filter - I've had bad experiences with this in the past. Once I put it in, some of it always seems to remain in the tank, leaking out into the water. If you do, ONLY PUT A LITTLE IN at a time.

How do you check your PH? Liquid testers? PH Monitor? You may want to check to make sure you're getting the right reading. Liquid testers can go bad after a while and monitors need to be calibrated again after a couple months.

If your plants aren't doing too well it's because of a couple things:

a) Adequate lighting for the plant (You may have plants that require stronger light)
b) Nutrients (Do you feed them fertilizers? - iron, phosphate, nitrate, micro/macro nutrients?
c) Source of carbon, which you already dose (Flourish Excel works well for a carbon source, but in my opinion, can get expensive after a while depending on tank size)

With more information, I can pinpoint the problem. What else is in your tank? Discus? Strangely enough, I've heard that even the urine from discus can soften the water (lower the PH).

Whew...a bit of an essay, but I'm sure an English teacher would appreciate that :) Nice to see another teacher on the forum.

Hope this helps!

-Aaron

[Innivus]

Hey all, thanks for the help.

Aaron, just to answer some of your questions, it's not so much the growing of plants as it is the low pH - I add supplements, and have appropriate plants for the light levels. Same as I've always done, but having just started adding excel to get rid of BBA. The driftwood is pretty old, but so is my liquid testing kit (but it seems to have not changed in reading a 7.0 out of the tap, as it always has). It also isn't a large piece of driftwood, either.

So I'm just a bit concerned about the 6.0 I've added some (just a little) crushed coral to the tank and that seems to have raised it a bit, but I'll be keeping an eye on it.

And I trust what Seachem says on the bottle ... but then again, I don't. :)

Oh, and Aaron, I always love essays. I've a bit of a fondness for them myself.

[Sharkbait]

Definitely keep an eye on it. Have you seen what your tap water's PH is after 24 hours? If not, leave a cup of fresh tap water on the counter for a day and then re-check the PH. If it's still 7.0, it's something in the tank.

Because you're adding crushed coral, make sure to check your KH as well. Coral will raise the hardness of your water.

When you check your PH, make sure you check it at the same time during the day. Every tank will have a 'PH Swing.' Typically this is of about .4 degrees. My tank has a swing of 6.3-6.6.

Let us know how it turns out.

[Blackwater Aquaria]

Hey all, thanks for the help.

Aaron, just to answer some of your questions, it's not so much the growing of plants as it is the low pH - I add supplements, and have appropriate plants for the light levels. Same as I've always done, but having just started adding excel to get rid of BBA. The driftwood is pretty old, but so is my liquid testing kit (but it seems to have not changed in reading a 7.0 out of the tap, as it always has). It also isn't a large piece of driftwood, either.

So I'm just a bit concerned about the 6.0 I've added some (just a little) crushed coral to the tank and that seems to have raised it a bit, but I'll be keeping an eye on it.

And I trust what Seachem says on the bottle ... but then again, I don't. :)

Oh, and Aaron, I always love essays. I've a bit of a fondness for them myself.In simple terms ,yes co2 will drop your ph,also you need to regulate
your Ph by means of a ph controller,or just run you co2 on a timer,to operate along with your lights,you do not want to add co2 @ night. As far as the blackbeard alge,to my limited knowledge there is nothing that will get rid of it
I just keep it under control by removing any wood and keep trimming the plants. Good luck Mike Deegan BLACKWATER AQUARIA:bandana:

[Chad Hughes]

How long has this tanks been in operation?

I've had experience with tanks two years and older that at some point accumulate enough organic matter in the substrate to influence the Ph, specifically lowering it.

If your tank is two years or older, an overhaul may be in order. Replacement of the substrate would be advisable.

Hope that helps!

[exv152]

Like Sharkbait said, KH needs to be monitored. I would even go further and say KH (carbonate hardness) is what determines the stability of your pH. Ideally, you want to keep the KH around 3-6º. I doubt the excel is lowering your pH, but I think the tank's buffer capacity has probably been reduced over time. A planted tank uses up KH over time and once it gets to 1º or less, you can experience wild swings in pH, or worse, a pH crash. Does your pH kit read anything lower than 6º? If it doesn't, if that's the minimal reading on your reference card then your pH may even be lower than that.

[TwoValveKid]

How long has this tanks been in operation?

I've had experience with tanks two years and older that at some point accumulate enough organic matter in the substrate to influence the Ph, specifically lowering it.

If your tank is two years or older, an overhaul may be in order. Replacement of the substrate would be advisable.

Hope that helps!

I'd go along this line too. How long has it been since you've tested pH? it can slowly fall over the course of time in a tank.

[kush]

I second the motion that you test your KH both at the tap and in your tank ASAP. A number of things might actually be causing the pH drop but, if the alkalinity in your tank tests less than 2 dKH increasing your buffering capacity will probably be part of the solution, regardless.

Two more ideas:

What is your light intensity and what kind of plants do you have? Under high-intensity lighting, if your carbon source is insufficient to meet the plants' growth demands, many plants will actually strip carbonate ions out of the water column (valisneria is particularly adept at this strategy) lowering buffering capacity.

A well 'seasoned' filter will lower pH, too - if you haven't cleaned your filter lately, you might want to give the filter media a good rinse.

BBA sucks. I'm never quite sure how it gets started but I suspect by overdosing iron. The only things I know that will eat it are SAE and American flagfish.

[Apistomaster]

If your water is staying between a pH of 6.0 and 6.8 but only varying a couple 0.2 points leave well enough alone. Many wish their water would.