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Kh and GH for Cichlids


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I've been researching and planning a 10 gallon shell dweller tank.  I know they prefer water with higher pH, GH, and KH.  I finally got some test strip to check the latter 2. I checked my betta tank and tap water. 

pH is about 7-7.2

KH is 40

GH is probably 60 (I'm not good with color shade matching)

All 3 of these values are not ideal for African cichlids. 

I've researched methods such as crushed coral to raise these values. But it doesn't last. 

Then I read about CaribSea African cichlid sand that supposedly keeps the values where they need to be for the life of the aquarium. 

Then I read about aragonite. 

Then I read about  oolite Aragonite. 

I think I'm just confused and overwhelmed by this. 

Can someone share some wisdom here?   Either experience with shell dwellers, any of these products, and whether or not it really does maintain levels for the life of the tank.   

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On 6/15/2021 at 8:10 PM, Gideyon said:

I've been researching and planning a 10 gallon shell dweller tank.  I know they prefer water with higher pH, GH, and KH.  I finally got some test strip to check the latter 2. I checked my betta tank and tap water. 

pH is about 7-7.2

KH is 40

GH is probably 60 (I'm not good with color shade matching)

All 3 of these values are not ideal for African cichlids. 

I've researched methods such as crushed coral to raise these values. But it doesn't last. 

Then I read about CaribSea African cichlid sand that supposedly keeps the values where they need to be for the life of the aquarium. 

Then I read about aragonite. 

Then I read about  oolite Aragonite. 

I think I'm just confused and overwhelmed by this. 

Can someone share some wisdom here?   Either experience with shell dwellers, any of these products, and whether or not it really does maintain levels for the life of the tank.   

Crushed coral is aragonite both should keep it stable for you but would also recommend adding sand on top since they like digging or you could all the crushed coral to the filter also

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Basically any calcium carbonate (including the shells they dwell in) acts as a pH buffer. Generally the aragonite sands will have magnesium in them as well as the calcium carbonate which will both serve to increase your kH and gH. While you may see a bump in your pH realize that this number is on a logarithmic scale so it may not be reasonable to expect to get your tap water to 8.0 from neutral (7.0). That is OKAY even if it shifts your pH to around 7.6 the cichlids will be more than happy, they may just need a drip acclimation or osmosis acclimation before you add them to the tank.

 

Products with calcium carbonate include; crushed coral, limestone, aragonite sand, oolite,  and African cichlid sand mix.

 

Keep in mind when the product descriptions states "increases pH" it is a misnomer unless it literally contains OH- (hydroxide), these products only act to buffer the pH which has the potential to raise pH.

 

 

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Posted (edited)
On 6/16/2021 at 2:46 AM, Biotope Biologist said:

Products with calcium carbonate include; crushed coral, limestone, aragonite sand, oolite,  and African cichlid sand mix.

 

On 6/15/2021 at 11:16 PM, Leo2o915 said:

Crushed coral is aragonite both should keep it stable for you

 

Thank you for the feedback. 

My understanding is that crushed coral eventually burns off and you need to replace it.  It goes away in a few months in a filter, maybe a year in the substrate.  I really don't want to be paranoid of when it burns off. 

Do the other products do as advertised and it stays stable for the life of the tank? 

I read on a saltwater forum that aragonite starts to stick together like concrete after a while.  Not sure if that's true, or particular to salt water.   

Edited by Gideyon
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Yes the calcium and the carbonate separate and dissolve into the water slowly over time based on how much already exists in the water. Since you are on the lower side of the kH and gH it will dissolve quicker at first than stabilize. With every water change you are adding new water that will then dissolve more calcium and carbonate ions and remove existing ions. This is why the buffers exist, when you do your water change it will not shock the fish with a pH swing it will simply dissolve more into the water. You will know rather quickly when you need to add more in this case because the shells that the cichlids hide in will start to get chalky or have holes in them. At this point the water is now dissolving the calcium carbonate in the shells because there are not enough ions in the water.

 

It takes a long time for this stuff to dissolve so it's not like you will have to add another 25 lb bag of sand each year to correct for the water. But it is also erroneous to think it will last the life of the tank. Having a bag of crushed coral in your filter as stated above works twofold. It both provides your tank the buffer it needs while also being an indicator for when to add more.

 

Also all calcium carbonate becomes cement like over time. That is how limestone and oolites are formed naturally. Cichlids are constantly digging and moving material around so you shouldn't have an issue with the sand becoming compacted

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On 6/16/2021 at 1:22 PM, Biotope Biologist said:

It both provides your tank the buffer it needs while also being an indicator for when to add more.

What would it look like when it's time to change?  Or is it completely gone?  I'm still not sure what kind of filter I'll be using. Either an hob, or internal canister. The former I'm not sure will have enough room.   The latter, no room.  Unless I do both and the hob is just filled with crushed coral. 

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