Thoughts on using crushed coral

[Thomas369]

I was wondering what people's thoughts are on using crushed coral to buffer PH and Kh? I have been using it in my tanks as I have extremely soft water and within a day or two after doing a water change my Ph will drop below 6. I joined my countries largest facebook fish group and was told it's bad to use. They said the constant leaching of minerals stresses the fish as the water isn't stable then and to add powder buffers instead. 

[Colu]

I use crushed coral in all my tanks in media bag in fliter as my water has a KH of 1 GH of 2 without crushed coral I haven't noticed any negative affects on my fish and it helps to keep stable water parameters my pH only fluctuate between 6.9 7.2 that with 100g of crushed coral in a 50 gallon tank  you can add more if you want a higher pH

Edited October 3, 2021 by Colu

[lefty o]

if you have very soft water that is lacking many minerals, crushed coral is a good thing. it helps put some of those minerals you desire into the water. imo using crushed coral will provide a more stable long term environment inside the aquarium than measuring out powdered stuff every water change guessing exactly how much you need. coral will only break down so fast based off of your PH.

[Chris]

I used to work in a pet store, and I always tried my very best to steer people away from "non-natural" PH/hardness altering products.

The problem is that there's no way for the average hobbyist to get exact measurements - you'll never know exactly how much water is in your tank (after displacement and evaporation), you'll never know exactly what your PH is (since test kits have a margin of error), you'll never know exactly if that teaspoon is exactly level or not, or if your scale is exactly accurate, etc...

Funnily enough, the exact thing they're saying is bad (the constant release of minerals) is actually what you want - a PH/GH/KH swing will almost always be far more harmful than a PH/GH/KH value that's too low or too high, within reason. That slow release of minerals allows the water to become harder over time instead of all at once, reducing stress on the fish.

Plus, it's reduced stress on you, too. It's far easier (and safer) to chuck a bag of crushed coral into your tank once every couple of months than to be testing and adding chemicals every few days/week. I'm sure a 10lb bag of crushed coral is way cheaper, too!

[StevesFishTanks]

I have hard water and I still use crushed coral.

I look at it like a safety buffer on standby

If my ph drops the water becomes more acidic and breaks down the crushed coral

[Patrick_G]

I started out using power to raise my gh/kh but I’ve recently switched to crushed coral.  It’s gentle and so easy to  use. If you’re chasing a very specific gh/kh level I’d go with a powder but otherwise the coral is the way to go. 

[Hobbit]

Like you, I have really soft water. I use crushed oyster shell (something very similar) in my tanks and it works really well for me. In fact, I had lots of it in my outdoor tubs along with some rocks from my yard. My pH, KH, and GH all stayed really low, despite adding wondershell and even powdered additives sometimes…

And yet my hundreds of Ramshorn snails all have PERFECT-looking shells. Super smooth without lines or pockmarks.

My platys also bred like crazy in these tubs. So the oyster shell must be doing something helpful!

[Thomas369]

On 10/1/2021 at 12:00 AM, Chris said:

I used to work in a pet store, and I always tried my very best to steer people away from "non-natural" PH/hardness altering products.

The problem is that there's no way for the average hobbyist to get exact measurements - you'll never know exactly how much water is in your tank (after displacement and evaporation), you'll never know exactly what your PH is (since test kits have a margin of error), you'll never know exactly if that teaspoon is exactly level or not, or if your scale is exactly accurate, etc...

Funnily enough, the exact thing they're saying is bad (the constant release of minerals) is actually what you want - a PH/GH/KH swing will almost always be far more harmful than a PH/GH/KH value that's too low or too high, within reason. That slow release of minerals allows the water to become harder over time instead of all at once, reducing stress on the fish.

Plus, it's reduced stress on you, too. It's far easier (and safer) to chuck a bag of crushed coral into your tank once every couple of months than to be testing and adding chemicals every few days/week. I'm sure a 10lb bag of crushed coral is way cheaper, too!

I thought something similar myself. I was also told not to feed flake food as it loses most of its nutrition when it meets water. 

[Hobbit]

On 10/1/2021 at 9:02 AM, Thomas369 said:

I was also told not to feed flake food as it loses most of its nutrition when it meets water.

That doesn’t make sense to me… I’m sure some nutrition dissolves, but if the fish are eating it in 1-2 minutes, you’ll only be losing a minuscule amount.

[Mmiller2001]

The problem with crushed coral is that it raises both KH and GH. This may be undesirable. I like using potassium carbonate as it's cheap, readily available and easy to calculate with a side benefit of extra potassium.

[Patrick_G]

On 10/2/2021 at 10:18 AM, Mmiller2001 said:

The problem with crushed coral is that it raises both KH and GH. This may be undesirable. I like using potassium carbonate as it's cheap, readily available and easy to calculate with a side benefit of extra potassium.

Good point, coral is great for those of us with low GH/KH but might not be the best solution for just low KH.

[SWilson]

On 10/2/2021 at 10:18 AM, Mmiller2001 said:

The problem with crushed coral is that it raises both KH and GH. This may be undesirable. I like using potassium carbonate as it's cheap, readily available and easy to calculate with a side benefit of extra potassium.

May I ask how you use the potassium carbonate (a link to another thread or article if you have one) in the aquarium?  Is there a resource out there at gives info about what concentration to achieve a certain level of increase in KH?  And how often do you have to re-dose? 

[Mmiller2001]

On 10/2/2021 at 11:45 AM, SWilson said:

May I ask how you use the potassium carbonate (a link to another thread or article if you have one) in the aquarium?  Is there a resource out there at gives info about what concentration to achieve a certain level of increase in KH?  And how often do you have to re-dose? 

There's not one specific article I could link you to unfortunately, but you would look at the type of fish you keep and try to emulate the ideal conditions for them.

I keep tetras and Apisto's, I know they are soft water fish and should be fine in 0 to 3dKH. You will just have to research your fish and find a happy medium and set that KH.

Also, my primary goal is plants. So I keep a 0dKH. And have chosen fish that can thrive within this parameter.

How I calculate the amount to use is here. 

https://rotalabutterfly.com/nutrient-calculator.php

All you need to know is the gallons and the compound you dose.

Example, I have a 20 gallon aquarium with water measuring 2dKH. I want to increase the tank to 4dKH.

I want true gallons, so let's say it's actually 16 gallons. It's not completely full, 3 inches of substrate and the aqua scape.

So I put 16 in the calculator, hit DIY and then select my compound. K2CO3 is potassium carbonate and is in the drop down box. I then choose dry dosing, because it's in powder form, and then use the drop down box to select dose to reach a target.

My target is 2dKH, because my tank is alread 2dKH and I want 4dKH. I will enter 2 in the ppm box and hit calculate.

The calculator then tells me I need to add 2.98g of potassium carbonate to raise my 16gallons by 2dKH. 

As far as how long KH last, it depends on the tank. You will just have to get a feel for things. Test KH after adding it, then test right before adding it some time later.

Also I will add that I would never move a tank up or down by more than 1.5 degrees in a 24 hour period. So if you needed to raise it by 10 degrees, do it over 7 days or so. This will give them time to adjust.

Edited October 2, 2021 by Mmiller2001

[CT_]

On 10/2/2021 at 10:18 AM, Mmiller2001 said:

The problem with crushed coral is that it raises both KH and GH. This may be undesirable. I like using potassium carbonate as it's cheap, readily available and easy to calculate with a side benefit of extra potassium.

I think you're just gaming the tests here. The gh tests only measure calcium and magnesium and you're just trading calcium for potassium.  Though, depending on what's in your water that may be good anyway since plants need potassium.

 

On 9/30/2021 at 12:55 PM, Thomas369 said:

They said the constant leaching of minerals stresses the fish as the water isn't stable then and to add powder buffers instead. 

It's a bit surprising to me that they would say that.  The carbonates added by the coral will buffer your pH up causing the crush coral to dissolve slower, creating a negative feedback loop.  If anything it makes your water chemistry more stable.

I don't do many water changes and use a TDS meter as to check that nothing has run away on me and everything has been very stable with constant flow over the CC in my HOB.

 

IMO, as long as you're happy with whatever steady state you reach (probably good for most fish unless you have something special) crushed coral is great.

[GardenStateGoldfish]

On 9/30/2021 at 4:49 PM, Colu said:

water has a KH of 1 GH of 2

I love crushed coral in all my tanks as well because my KH is only two and I have such heavy plant loads that they suck it all up very quickly, I found myself doing water changes for KH instead of nitrates, now I have greatly extended my need for water changes and the KH really enables the plants to do their thing! 

[Hobbit]

Aww man, you nerd sniped me @GardenStateGoldfish!

I had assumed that plants couldn’t use carbonate as a carbon source…

And then I looked on Google and found these articles from 2018 and 2019:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5983714/

https://www.science.org/doi/abs/10.1126/science.aay5945

The first one only covers saltwater autotrophs (including algae and plants) and land plants, but it’s still an interesting overview. (For those who want all the nerdy details.)

Some interesting quotes:

“During the last decade, there has been significant progress of our knowledge on the mechanisms of HCO3− transport and CCM in cyanobacteria, algae, and seagrass species due to improved genetic and molecular tools and electrophysiological approaches.”

”Photosynthetic marine organisms as well as submerged freshwater plants can use this abundant HCO3− as a source for the biosynthesis of [organic carbon].”

“Unlike in land plants, photosynthesis in many aquatic plants relies on bicarbonate in addition to carbon dioxide (CO2) to compensate for the low diffusivity and potential depletion of CO2 in water.”

”We show, globally, that the frequency of plant species with this trait increases with bicarbonate concentration. Regionally, however, the frequency of bicarbonate use is reduced at sites where the CO2 concentration is substantially above the air equilibrium, consistent with this trait being an adaptation to carbon limitation.”

So it looks like plants can use carbonate for photosynthesis, but from what I’m reading, it’s a lot more work to use carbonate versus using CO2. It’s like eating raw corn versus eating ground+cooked cornmeal.

For one thing, carbonate is a lot of work to transport into the cells. CO2 can just diffuse in, no work required, but carbonate is slightly larger and has a charge on it, which means it needs special transportation.

Anyway…

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