Before adding CO2...

BUt if I change water once a week, wouldn't that effect how fast the crushed coral will take effect? I hear that the coral will take time to dissolve into the water, and if I change water often, then how will the coral take effect?

Say, I change water once a week, and each time I change the water, the kH will drop? If it drops by 2 or something, then I will have to wait for the crushed coral to take effect again? Will I then have to remove the CO2 until it reaches 3 again everytime I change the water?
 
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I do weekly 30% changes and, from what I've heard, I won’t have any detectable KH drop from those water changes.

I suppose if you are seeing a drop you could probably treat the change water with baking soda so that it is at an equal level with the aquarium, but again, I’ve been told it won’t be noticeable.
 
Maybe your aquarium is big, but mine is a 10 gallon. But I gues if we both change water 30%, it is the same proportionally.

So if I put the crushed coral in, and I get the kH up to 3, do I take out the crushed coral? Or leave it in there? I will be adding the CO2, will that lower the kH? If I get the kH to 3, then I add the CO2, it will lower it again, but the coral will keep that in check. Or do I get to 3 and then take out the coral and add CO2? Will the CO2 and the crushed coral keep each other's level in check?

IF I do that, the gH and the pH will also stay like before?
 
The effects of crushed coral are slow, but they will eventually hit a peak and so you'll want to just leave the crushed coral in there all the time. I haven't heard an exact figure as to how often you are supposed to replace it, but it should last months. This is also why you don't want to put too much in there, just start out low and add more if your tests indicate you need it.

As for how KH, CO2 and PH relate…

Adding the crushed coral will raise your KH and PH, but will not affect CO2.

Adding CO2 will lower your PH, but will not affect KH.

I’m not sure of the relationship between crushed coral and GH so hopefully someone else can chime in if there is any, but the addition of CO2 won’t cause any problems with it at the very least.

Basically with a KH less than 1, your pH is very unstable and you’d have to have a pH level of basically 6.2 or less in order to exhibit maximum growth from your plants.

By bringing your KH up to 3.0 you can then shoot for a pH between 6.5 and 6.7 and that’ll give you around 25ppm CO2 (give or take) and you’ll have a great growth environment for both your plants and fish.
 
Since we're talking pros and cons, here's why I choose baking soda over coral-

First and foremost, crushed coral does in fact increase GH. Coral is essentially carbons, calcium, magnesium and traces. Calcium and magnesium are the primary compounds which determine GH. Since I prefer SA, soft water fish, I strive to keep the GH as low as possible. Coral would increase the GH. My water has a GH of 3 out of the tap, I'd like to keep it that low.

Secondly is the control. I've determined that I need to add only 1/8 teaspoon of baking soda time I change out 25% water. By doing this I keep the kh between 3 and 4 degrees constantly. I actually disolve the baking soda into the water before adding it to the tank, which reduces increased risk of pH shock caused by swings. If I used the coral in filter method I would need to add the water then wait for the concetrations to rise up. (Plus, when injecting CO2, everytime you change your water you are introducing water with a vastly different pH than your tank).

Also, baking soda does not need to be added daily. Like Tricky pointed out, KH levels don't change based on CO2 injection or pH. The only loses of KH besides water changes come from evaporation or if you expose your water to acids like those produced by peat. (Also, if you are injecting CO2, you won't want to add peat to your tank unless it is below the substrate. Peat in your filter will screw up your KH readings massively).

Anyway, just my take and my preferences. And as tricky stated, when using baking soda you do need to be very careful that you aren't altering the pH too quickly.
 
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benedictj said:
Also, baking soda does not need to be added daily. Like Tricky pointed out, KH levels don't change based on CO2 injection or pH. The only loses of KH besides water changes come from evaporation or if you expose your water to acids like those produced by peat.
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Baking soda doesn't lose effectiveness? That is my mistake there, I was under the impression that baking soda wore off much like that of bottle buffers such as pH Up and Down.

I keep several Blue and Bolivian Rams between my three tanks and would like to attempt to breed them down the road so the effects on GH are important to me as well.
 
Nope. A bi-carb is a bi-carb. It will wear off if you're using it as a cure for an upset stomach :soda:
 
benedictj said:
The only loses of KH besides water changes come from evaporation or if you expose your water to acids like those produced by peat.
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If you're injecting CO2 your water is being exposed to acid. That's the whole point of the watch-your-KH excercise.

Coral is long-term, slow-dissolving. Baking Soda is short-term, fast-dissolving.

You probably don't need it. (insert KH test kit here).

If you do need it, you can look at the pros and cons.

Benedictj makes a decent case for baking soda.

I prefer crushed coral. Also keep softwater fish. I use enough coral to keep my KH at about 4 (comes out of the tap at about less than 1dKH). Yes the GH goes from about 3 to about 5. The Gouramis spawn less than they used to. I'm ok with this. The coral is extremely stable and after the initial getting it just right period, its no maintenance. Same coral for over a year. Test the KH once a month or so and check the coral at filter cleanings.

Baking soda dissolves completely and then thats what you've got. Get busy, miss a weekend and keep your fingers crossed. Coral is always sitting there being slow, being steady. Doing its thing. Once you find the balance point it replenishes itself as it gets used up, no need to be concerned with osmotic shock (which shouldn't be a problem with the baking soda if you make sure you know what you're doing).

When I do my weekly(-ish) 50%, the KH probably drops a point or so for a little bit. No harm to date.

Rushing into either without doing the reading and asking some questions out here is a pretty good way to kill fish.

Get good pH and KH test kits. Its where you need to start.
 
carpguy said:
If you're injecting CO2 your water is being exposed to acid. That's the whole point of the watch-your-KH excercise.
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I don't mean to be a nit picker or hi-jack, but I'm not sure that this is fundamentally accurate. Can you explain a bit more? To my understanding, CO2 is basically inert. It does create carbonic acid, but as far as I understand it, that is generally a temporary state and it's effects are minimal.
 
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