Having CO2 and Buffering pH/KH

[Graft]

I've got a tank that I am presently working on. I added some DIY CO2 to it and have found from members on the board and from reading that CO2 will acidify my water. I have had some pH shifts and am presently compensating with Baking Soda to keep my KH around 3 (and pH at 6.6). I have only been doing this for 2 days, so I have little experience.

I do not want to use crushed coral, because I'd like my fish to have soft water (and I don't want to treat with peat). My water is presently at 10 degrees GH and I don't want it any higher.

I am wanting to get some experiences or info from members that have tried CO2 without using a buffer that will increase the GH. I've read alot and my eyes are strained now, so if anyone has anything they'd like to share, please do!

Thanks!

 

[rdd1952]

You probably won't find many people that have used CO2 without a buffer AND still maintaining soft water. Soft water technically means you have no buffering capacity. Therefore, if you add CO2, you will likely end up with a pH crash somewhere along the line. If you have a higher GH, thus buffering capacity (and hard water), you can use CO2 without any fear of pH problems. Unfortunately, those of us with soft water, have to add something to counteract the effects of CO2 or even driftwood which will also have the effect of lowering pH but at least that's over a longer period of time so there isn't the danger of losing fish due to a sudden swing in pH.

I currently use a small amount of crushed coral in my tanks and don't have any problem with water condition. It really depends on how soft your water is from the tap. My tap water has a KH & GH of 0. Basically, the test water turns yellow with the first drop, never turning blue at all. In my 29 gallon tank, I have approximately 1 teaspoon full of crushed coral in the filter pack. In the 75 gallon, it is about 2 tsp. That keeps my pH about 6.6 to 7.0 and the KH is still only about 4 which is still soft. If you use crushed coral, experiment a little. Just add a small pinch, maybe a 1/4 tsp. Wait a couple days and test to see what effect it had. Then add a little more if you still want to raise it a little.

 

[sinistral]

If you have a higher GH, thus buffering capacity (and hard water), you can use CO2 without any fear of pH problems.

Just one small point about the previous posts:

I believe what you mean to refer to is KH, or carbonate hardness. This is a measure of the buffering capacity for pH of your tapwater. KH and pH will (generally) go up if baking soda (sodium bicarbonate) is added.

GH is general hardness, and a measure of calcium and magnesium ions (mainly). This has no direct effect on pH.

This is one of the best sites I've encountered for reading about the technical aspect of CO2 titration in the aquarium.

Most of the articles there refer to adjusting (slowing) the flow of CO2 to control pH levels, although with a low KH, that may not be possible for you.

EDIT: You might also try inquiring in the planted tanks section, as the folks there tend to think about (and use) CO2 and buffers with some frequence

 

[rdd1952]

If you have a higher GH, thus buffering capacity (and hard water), you can use CO2 without any fear of pH problems.

Just one small point about the previous posts:

I believe what you mean to refer to is KH, or carbonate hardness. This is a measure of the buffering capacity for pH of your tapwater. KH and pH will (generally) go up if baking soda (sodium bicarbonate) is added.

GH is general hardness, and a measure of calcium and magnesium ions (mainly). This has no direct effect on pH.

Thanks for the correction.

 

[Def]

have approximately 1 teaspoon full of crushed coral in the filter pack. In the 75 gallon, it is about 2 tsp. That keeps my pH about 6.6 to 7.0 and the KH is still only about 4 which is still soft

I'm amazed. I have a KH of about 1 out the tap, and I need to add 1 level tsp of bicarb per 10 litres of water to raise it to around 8dkh. Raising the kh with crsuhed coral has never worked for me unless I added giant amounts.

The other problem with crushed coral is that it eventually uses up its buffering capacity. So you have aload of coral in the tank that you either have to take out, or keep adding to.

 

[rdd1952]

I put mine in the filter pack (in the 29 gallon). It basically takes the place of carbon and not only helps with buffering but also gives the bacteria more surface to attach to. In the 75 gallon where I am using canister filters, I just have a filter pack hanging in the tank with the crushed coral in it. I tried once to just sprinkle it on the gravel but that looked like crap and I had to change the gravel completely to get rid of it after it got mixed in.

 

[Graft]

My tap water is:

GH - 8
KH - 0
pH - above 8.8 (as I just found out with a High pH test kit)

My KH fluctuates way too much in my aquarium with CO2, loosing about 1 degree a day. I'm going to try Baking Soda for a week or so and see if I can come up with a daily dose that will keep everything in check. If not, then the crushed coral is probably the ticket and I'll invest in some water softening equipment.

The search capabilities on this site have never given me a response from the plant section, so I never knew it existed. Time to do some reading.

Thanks for the responses!

 

[Fiori]

I had to add a whole bag of crushed coral to the sand in my 40 UK gall tank - I tried to keep it at the back out of sight, cos it looks crap. But it keeps my water at a steady 6.8 and I suppose I've got used to it. I wish a teaspoon worked with me!