Dosing with calcium carbonate? - The Planted Tank Forum
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post #1 of 8 (permalink) Old 11-22-2004, 04:23 PM Thread Starter
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Dosing with calcium carbonate?

I've got a 40 gal regular tank set up with gravel/Eco Complete substrate, 2x96 watt lighting and pressurized co2 w/ph controller.

My kh is only 3 (down from 5 last time I tested it about a month ago), and I'm wondering if I need to raise it a little to avoid a potential ph crash.

I ordered calcium carbonate from greg watson by mistake (meant to order potassium), but I haven't used it before and am not sure how to dose (nothing on Chuck's calculator on this).

Should I be doing something about this or is 3 within a safe range?

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post #2 of 8 (permalink) Old 11-22-2004, 04:28 PM
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kh of 3 is safe if you can get your ph down to about 6.7... you'll be in the target zone per chucks chart~
that was my whole issue, bad ph swings.. my kh was way low.. .. added two limestone rocks.. those helped rise my kh, now my ph swings are null, kh has balanced.. and plants are pearling~ been like this now for 2 strait days... .everythings in heaven. i'm gettin about an 1' a day plant growth~.. its beautiful~
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post #3 of 8 (permalink) Old 11-22-2004, 08:58 PM
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Calcium carbonate is basically the active ingredient in crushed coral and limestone. It will raise your dGH and your dKH but it is only slightly soluble. You are probably better off with crushed coral or limestone in the filter as it will be a larger grain size than calcium carbonate (don't want it floating around in the tank). If you do decide to use this, put a little down in the gravel or in the filter and monitor BOTH pH and GH - the pH will go up. If you are already happy with your GH, just use baking soda (sodium bicarbonate) to raise the KH.



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post #4 of 8 (permalink) Old 11-22-2004, 09:42 PM
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I have really low KH and GH out of the tap (KH around 0-1!!!!)...I think I share the same water as Corigan too. We both have to dose Calcium because of "curled leaf" syndrome. I actually use Kent's liquid calcium and that has worked really well for me. I've actually seen great--or greater new growth and long-term stability of new leaves from my P. stellatus (E. stellata broadleaf)...whereas before new leaves eventually curled up and got pinholes and withered away. I think Corigan uses Turbo Calcium dissolved with Epsom salts. I was hesitant on using granules or pure CC since it turns your tank so cloudy. The liquid form by Kent is already predissolved in DI (deionized) water so I just dose 1/2 teaspoon at every water change.

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post #5 of 8 (permalink) Old 11-28-2004, 10:51 PM Thread Starter
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Thanks for the replies - I've been out of town or I would have responded sooner.

Hmmm. My a. reinickii (sp.?) has been a bit puckered, maybe this is why.

I've got big pieces of limestone (holey rock) in all my African cichlid tanks to raise kh and ph. I actually prefer this sort of "time-release" method of treating my water, since it's more consistent. However, it's also harder to calibrate to get the level you want. I guess I'll just have to fool around with it.

I'm sure I've got a spare chunk of regular limestone laying around somehwere. Maybe I'll crush some and add it to the filter. I'm running an Eheim canister on this tank, so it would be easy enough to add it, I think.

Any suggestions on what kh level I should shoot for (and how much limestone I'd need to use to get there)?

Thanks again.
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post #6 of 8 (permalink) Old 11-29-2004, 03:14 PM
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Originally Posted by fishwife
I ordered calcium carbonate from greg watson by mistake
I think you will find that the calcium carbonate Greg sells is actually calcium magnesium carbonate (dolomite) in powder form.

Georgiadawgger's suggestion below is convenient too. The water here in NYC is very soft and I use it without increasing hardness. I suppose it depends what you are growing and intend to grow.

Andrew Cribb
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post #7 of 8 (permalink) Old 11-29-2004, 04:03 PM
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The first question that comes to my mind is WHY did your kh drop from 5 to 3? I too had this happen before and didn't think much of it. Until one day I checked my pH and it was down below 6. Measuring my KH is was below "1 drop". After doing some experimenting, I found that I had 'toxic' driftwood. Since removing it, my KH has stablilized.

So, do you know what's causing your KH drop?

FWIW, Brian.
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post #8 of 8 (permalink) Old 11-30-2004, 06:41 AM Thread Starter
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Not sure. There has been some variation in the kh measured out of my tap. I have no idea why that would be. It's never much, but when you're talking about these low levels a degree or two can make a big difference.

There's driftwood in the tank, but it's been there for six months or more. Ph is consistent. I've got a ph controller running my pressurized co2, and there hasn't been a drop -- it aways reads 6.9 or 7.0.

I've done kind of a big replanting weekend before last, but that was after I got the low reading. Before that, nothing appreciable had changed in the tank for months.
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