pH

Tug

Lifetime Charter Member
Lifetime Member
Jan 5, 2009
1,150
9
38
Washington, DC
Before adding CO2 to my brackish water tank the pH would be around 7.6 but with CO2 it is closer to a pH of 6.4 or so. The dKH is 4 and SG is 1.005; plants seam fine, fish (BBG's and guppies) seam fine. What concerns me is the number of times I have read that a pH this low is a problem. Even though I see evidence to the contrary. What can I say that would address this issue? I have a 10 gallon tank. I know the change in pH from CO2 enriched fresh water tanks is not an issue (forgot why :eek:) - is it the same for brackishwater tanks?
 

Philosophos

Lifetime Charter Member
Lifetime Member
Mar 12, 2009
1,346
0
36
I would hate to see this one slip off the front page without a reply; I find your brackish experimenting to be something of interest. That being said, I'll do the best I can to answer, but I'm honestly not familiar with brackish or salt systems.

Your main concern with fish stress is KH alterations and osmoregulation; CO2 does not effect this, and if anything would convert free calcium to CaCO3 more rapidly I would guess. The stress comes later on as an issue of acidosis damaging the gills, which is something that I'm unsure of how greatly it varies by species. I've never tried sticking a brackish or LTK cichlid in water with 20KH and 30ppm CO2, and all of the fish I keep prefer acidic water.

-Philosophos
 

Biollante

Lifetime Charter Member
Lifetime Member
Jun 21, 2009
3,210
3
36
Surprise, AZ
NaHCO3 v.CaCO3

Hi Tug, Philosophos,

While not a brackish water expert, I have kept brackish water tanks for 20 or so years, though planted, specific has only been a few years.

Normally I do not concern myself too much with pH drops associated with CO2 injection.

In your case, I will make an exception, lucky you! :p

I think 4 dKH is a really low amount of buffering for a brackish water setup, I would like to see more like 12-20 dKH. Baking soda, NaHCO3 is the usual choice. It will raise pH through addition of Hydrogen.

I prefer for this purpose Calcium carbonate, CaCO3 this increases carbonate and calcium so GH and KH will increase.

By increasing the KH and GH with the addition of lime instead of baking soda has the advantage increasing the buffering capacity and not simply raising the pH. This may seem a distinction without a difference but the pH drop you are experiencing is the addition of a weak acid to a water column that has insufficient buffering.

As Philosophos points out it is the osmoregulation of your with which you are concerned.

An article that is a good (I think) explanation of alkalinity versus pH. MARINELAND.COM - DR. TIM'S LIBRARY

I hope this helps or better yet someone who has a vague idea of what they are talking about shows up. :eek:

Biollante
 

Tug

Lifetime Charter Member
Lifetime Member
Jan 5, 2009
1,150
9
38
Washington, DC
Wow, it's not often we get the chance to use osmoregulation in a sentence, except when talking to another aquarist.

Here are a couple bandages.
1. I figure I need to raise KH slowly. So, I'll add about 1/16 tsp sodium bicarbonate daily untill I use something else.
2. I got some chalky looking rock from a lfs months back and added that (probably useless).
3. I have some (not sure if this is a good idea at all) RainGrow's Natural lime (derived from dolomitic lime) but was hoping I could find more information regarding the contents before using it.
What's on the label is;
Ca - 7.0%
CaCO3 - 17.0%
CaCO - 9.8%
Mg - 4.0%
MgCO3 - 14.0%
MgCO - 6.7%

Just thought I would post this while I search for other ways to raise KH. K2CO3, CaCO3 or MgCO3?. Thank you both for the help.
 

ordloh

Prolific Poster
Jul 30, 2009
39
0
6
37
Singapore
since 20% of your product is carbonate, you can add 50mg per liter of water to raise kH by 1. i wonder what the other 70% is.
 

Philosophos

Lifetime Charter Member
Lifetime Member
Mar 12, 2009
1,346
0
36
The whole works looks like MgCo3 and CaCO3, the analysis is just repeating its self to show how much of certain elements in different forms for the sake of various measurement. My concern would be solubility; it takes some work to get either compound into the column. Perhaps a reef water conditioning product at lower dosage would work; the sort that has replaced calcium reactors.

-Philosophos
 

Tug

Lifetime Charter Member
Lifetime Member
Jan 5, 2009
1,150
9
38
Washington, DC
Shazam, nice work you two. I have the same concerns as well. One place I found a little more info on the product mentions essential oils (probably to keep everything in suspension) which is another concern, let alone the cost. Yea, I'm just a little reluctant to add the RainGrow product. About the solubility of CaCO3. Remember that DIY reactor (reactor/needlewheel). If I found CaCO3 in a form that could go into that, the CO2 might help get it into solution. Right? Wish I knew what the chalky rock was I have. I might have to take a hammer to it and fit it into the reactor, or as we say at work, "give it some love". Thanks for reading the post and keeping me moving on this one.
 

ordloh

Prolific Poster
Jul 30, 2009
39
0
6
37
Singapore
You can dip the chalky rock in vinegar to see if it reacts. Yup, calcium carbonate dissolves in carbonic acid, so putting it in your reactor will help it dissolve. The carbonates turn into bicarbonate.
It'll be easier to fit coral chips/oyster shells into your reactor and you won't need to smash your rock.
 

Tug

Lifetime Charter Member
Lifetime Member
Jan 5, 2009
1,150
9
38
Washington, DC
Just a little loven, early in the morning. Thanks for the vinegar test - lots of little bubbles. Tiny bubbles, makes me happy. :D
I picked up the rocks from a marine aquatics supply store so it might be that they were for a reactor in the first place. I'll try and get back out there to find out and see what else they can tell me.
CaCO3 + CO2 + H2O → Ca(HCO3)2.
Some questions might be:
Does this add to the availability of carbon for the plants and will the relative inaccuracy of the drop checker be effected?
One observation of pH and KH. The pH went from 6 to 6.4 fairly quickly and the KH was 1dKH and went to 3dKH in the same amount of time. I also added 1/16 tsp of backing soda.
 

Philosophos

Lifetime Charter Member
Lifetime Member
Mar 12, 2009
1,346
0
36
CaCO3 isn't the best source of calcium for plants; low bioavailability. I'd imagine the same is true of its carbon content. Plants don't need a whole lot of calcium compared to carbon either, so I doubt it'd make for a noticeable difference. Just guessing on this one.

The drop checker shouldn't be effected.

-Philosophos
 

Tug

Lifetime Charter Member
Lifetime Member
Jan 5, 2009
1,150
9
38
Washington, DC
Steady pH 6.8 and 3 dKH. Thanks again for all the support.
Philosophos;42394 said:
I'd imagine the same is true of its carbon content.
Will this mean the CO2 is being bound with Ca and reducing the levels of CO2 coming from the reactor? I should be able to see for myself when the new batch of yeast kicks back in, but it's just my luck that it's a slow batch.