Crushed Coral to Increase GH + KH

GR1KTR

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Jun 25, 2013
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I'm aiming for 3-6KH, 2-8GH and a consistent pH of no more than 7.5 in an 11g (44L) planted tank. My tap water parameters are 6.8pH, 1-2GH and < 1KH. I've used powdered buffers in the past, but have had great difficulty maintaining consistent GH / KH / pH following water changes. I see that many have better luck with a natural buffer like crushed coral.

1. Are there any issues using crushed coral to maintain the right GH + KH levels for a planted tank?

2. Are there types of coral that are better suited than others?

3. How much should I use?
 
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Yo-han

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Why would you? Just add cheap epsom salt (MgSO4 and CaCl to raise GH a little) no need to raise KH unless using a pH controller. I would kill for such tapwater, saves me hundreds of bucks on RO-water. Easier to keep even the most demanding Toninas and Eriocaulins and I heard plants get away with lower CO2 concentrations with low KH as well.

If you really want to raise KH as well I would add baking soda to the list above, cheap buffer and more constant than crushed coral.
 

GR1KTR

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Yo-han;115819 said:
Why would you? Just add cheap epsom salt (MgSO4 and CaCl to raise GH a little)

I have a lot of trouble with maintaining a stable GH + KH using powdered stuff like epsom salt. I've used epsom salt, bi carb and other commercial powders (Seachem etc.) previously. I'm hoping that crushed coral may be the solution I'm after. It will take some playing around with no doubt, but it will be worth the time if I can consistently hit 3-6KH, 2-8GH and a pH of no more than 7.5.

RE: MgSO4 + CaCl - does crushed coral contain these also? If not, what is it likely to contain?

no need to raise KH unless using a pH controller

I'm afraid this seems to go against what I have learned previously. Don't many plants suffer with low KH? Won't this mean that pressurised CO2 will dramatically lower the pH of my water?
 

Tom Barr

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Dolomite if you want something that is slow dissolving.
CaCO3, does not add any Mg, whereas dolomite does.

CaSO4 and MgSO4 works well instead.

This does not affect KH, so you can dose whatever you want and have no effect on KH.
GH booster is a mix of those + K2SO4.

So K, Ca, Mg are all covered.
 

Yo-han

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Crushed coral won't give you a stable KH/GH neither, it will rise fast or slow depending in the amount. Changing water and it is low again, rising through the week. I don't see why that would be better than a low but steady KH.

About the low KH, try googling Amano. All his non stone scapes have a KH of 1... GH a little higher but this will be no problem adding with salt. It doesn't need to be very stable (impossible because plants use it). The pH drop is from pH controllers and changing KH. If your KH rises a little a lot more CO2 will be added. Fish don't really care about pH changes Ca2+ + HCO3-. Not sure about the form of magnesium. I think very little is in crushed coral but not sure.
 

GR1KTR

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Thank you Yo Han and Tom.

Dolomite if you want something that is slow dissolving.
CaCO3, does not add any Mg, whereas dolomite does.

CaSO4 and MgSO4 works well instead.

This does not affect KH, so you can dose whatever you want and have no effect on KH.
GH booster is a mix of those + K2SO4.

So K, Ca, Mg are all covered.

I will research dolomite some more. If that turns out to difficult I'll just keep adding powders (begrudgingly).

Crushed coral won't give you a stable KH/GH neither, it will rise fast or slow depending in the amount. Changing water and it is low again, rising through the week. I don't see why that would be better than a low but steady KH.

About the low KH, try googling Amano. All his non stone scapes have a KH of 1... GH a little higher but this will be no problem adding with salt. It doesn't need to be very stable (impossible because plants use it). The pH drop is from pH controllers and changing KH. If your KH rises a little a lot more CO2 will be added. Fish don't really care about pH changes Ca2+ + HCO3-. Not sure about the form of magnesium. I think very little is in crushed coral but not sure.

From this I understand that KH is not so important. What's more beneficial is the steady KH of
 

fortunebrass

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Jul 10, 2013
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Crushed Coral to Increase GH + KH

The figures are useful, indeed, but they're not universal. Everything, mainly, depends on the initial pH. The lower it is, the more prominent changes you'll see. But as it becomes higher, the changes will slow down progressively until they stop.
 

GR1KTR

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fortunebrass;115997 said:
The figures are useful, indeed, but they're not universal. Everything, mainly, depends on the initial pH. The lower it is, the more prominent changes you'll see. But as it becomes higher, the changes will slow down progressively until they stop.

Very helpful, thanks. Do you think I'll be alright with a pH of 6.8?