Is it worth keeping the crushed coral in my filters?

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AmyKieran

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In my 190l tank I am keeping Malawi cichlids that I buffer the gh/kh/ ph with malawi buffer and cichlid salt. This achieves 7.8+ ph 10kh and 18+gh if I remember rightly.

Before I started using these buffers, I tried putting crushed coral in my filters but this did nothing. Since getting my water parameters to where I want them, I have just left the bags of crushed coral in my filters.

I must have over 2kg of crushed coral in both of my filters , which could be used for lots more media (if the coral isn’t helping)

Would anyone reccomend taking them out, or leaving them in?

If the answer is take them out -

What filter media should I add in their place ?

My current filter setup is as follows


APS 1000ef

Various density sponges - bio rings (and a bag of crushed coral) -
plastic biological filtration - filter wool

Fluval 207

Sponge - bio rings (and a bag of crushed coral) - plastic biological filtration - phosphate pad - filter wool


Any other advice about my filter setup is also welcome :)
 

GaryE

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I've never used crushed coral, but would it not have its surface covered with archaea and bacteria?
 
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AmyKieran

AmyKieran

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I've never used crushed coral, but would it not have its surface covered with archaea and bacteria?
Yes possibly, obviously I have a lot more media in both filters that also carry bacteria, but I’m not sure if that would be enough to prevent a cycle crash
 

GaryE

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Malawi keepers often have terrifyingly overstocked tanks, and that would leave the cycle prone to crashing. Still, I have never had a cycle crash in any tank, ever. Moves, long power blackouts - things just keep rolling and I don't see any problems with the fish.
 

Byron

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Crushed coral will remain effective for years. And I mean years. It slowly dissolves, increasing pH, but if you leave the crushed coral "as is," it will be relatively stable. Years ago I used dolomite, just three tablespoons in a mesh bag in the canister filter, and my pH in that tank which had been below 5 remained around 6.4-6.5 for several years.

That explains the duration. But this may not be all you need. First, what is the GH, KH and pH of your source water? And for comparison, what is the GH, KH and pH of the aquarium water? Second, crushed coral is not an effective buffering, it is better to use dolomite which is calcium and magnesium.
 
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AmyKieran

AmyKieran

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Crushed coral will remain effective for years. And I mean years. It slowly dissolves, increasing pH, but if you leave the crushed coral "as is," it will be relatively stable. Years ago I used dolomite, just three tablespoons in a mesh bag in the canister filter, and my pH in that tank which had been below 5 remained around 6.4-6.5 for several years.

That explains the duration. But this may not be all you need. First, what is the GH, KH and pH of your source water? And for comparison, what is the GH, KH and pH of the aquarium water? Second, crushed coral is not an effective buffering, it is better to use dolomite which is calcium and magnesium.
I will do a test on both tomorrow, but even when starting off, the crushed coral did not change any of the values stated
 

Byron

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I will do a test on both tomorrow, but even when starting off, the crushed coral did not change any of the values stated

The test numbers may tell us why. But while I think of it, there are other factors too, like organics, that may have a stronger pull depending upon the source water parameters.
 
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AmyKieran

AmyKieran

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Okay apologies for long response

I have posted the results of the tap water and my aquarium water below :)


Tap -

Ph - 7
Kh - 2
Gh - 3


Aquarium -

Ph - 8
Kh - 6
Gh - 11

Every week I religiously change 75% of water and replace with fresh, aswell as roughly 20g of both cichlid salt and Malawi buffer


Thankyou
 

Byron

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Okay apologies for long response

I have posted the results of the tap water and my aquarium water below :)


Tap -

Ph - 7
Kh - 2
Gh - 3


Aquarium -

Ph - 8
Kh - 6
Gh - 11

Every week I religiously change 75% of water and replace with fresh, aswell as roughly 20g of both cichlid salt and Malawi buffer


Thankyou

Agree pn water changes here. Prepare the water outside the aquarium in another container so what is added is equal in parameters to the tank water. Your tap water numbers indicate very soft water which is unfortunately opposite of what your Malawi cichlids must have.
 
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AmyKieran

AmyKieran

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Agree pn water changes here. Prepare the water outside the aquarium in another container so what is added is equal in parameters to the tank water. Your tap water numbers indicate very soft water which is unfortunately opposite of what your Malawi cichlids must have.
I know it didn’t help really. I fill up buckets and add the cichlid salt + Malawi buffer and mix for a while to dissolve in order to achieve the numbers in my tank.


But in terms of my original question, do you think keeping my crushed coral in will be beneficial?
 

malfunction

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I’d say get rid of it. You already have a working solution for keeping your GH & kh stable, so you don’t need the crushed coral for that. I’d replace the coral with media. If you’re concerned about it impacting your beneficial bacteria, then remove it gradually, a little at a time. You could also add bottled bacteria to be safe, but that’s probably overkill.
 

Byron

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I know it didn’t help really. I fill up buckets and add the cichlid salt + Malawi buffer and mix for a while to dissolve in order to achieve the numbers in my tank.


But in terms of my original question, do you think keeping my crushed coral in will be beneficial?

This is not easy to answer because the chemistry of the water in an aquarium has several factors affecting it. That is why beginning aquarists who think they can add "pH down" to lower the pH end up killing fish. One has to know the entire chemistry of the water because all of the parameters are connected. If the GH and pH (I never worry about KH here) remain stable in the aquarium from water change to water change (test both just before the W/C), then things are stable. I would tend to leave well enough alone.

Mixing the water beforehand is fine, no issue there.
 
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AmyKieran

AmyKieran

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This is not easy to answer because the chemistry of the water in an aquarium has several factors affecting it. That is why beginning aquarists who think they can add "pH down" to lower the pH end up killing fish. One has to know the entire chemistry of the water because all of the parameters are connected. If the GH and pH (I never worry about KH here) remain stable in the aquarium from water change to water change (test both just before the W/C), then things are stable. I would tend to leave well enough alone.

Mixing the water beforehand is fine, no issue there.
Yeah all values are consistent water change to water change and my fish are doing great, I just feel there is an opportunity for better filtration (if my crushed coral is doing nothing)
 

Byron

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Yeah all values are consistent water change to water change and my fish are doing great, I just feel there is an opportunity for better filtration (if my crushed coral is doing nothing)

First, any media in the filter will support biological filtration. It does not have to be special. The foam/sponge, ceramic disks, stones, carbon, limestone rock/gravel...it all gets covered with a biofilm and bacteria stick to it. The grains of sand or gravel in the substrate also act as biological filtration.

And as I said previously, this crushed coral may be a factor in the readings, and if all is well, it is safer to leave it.
 
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AmyKieran

AmyKieran

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First, any media in the filter will support biological filtration. It does not have to be special. The foam/sponge, ceramic disks, stones, carbon, limestone rock/gravel...it all gets covered with a biofilm and bacteria stick to it. The grains of sand or gravel in the substrate also act as biological filtration.

And as I said previously, this crushed coral may be a factor in the readings, and if all is well, it is safer to leave it.
Okay thankyou :)
 

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