# Do I need to add calcium to my water?



## Surya (3 Sep 2018)

I live in the North West and have very soft water (GH 1-2, 1.82 Clarke). I have recently started using pressurised CO2 and have the APF EI starter kit on order, which comes with magnesium sulphate. But I'm wondering if I need to add a source of calcium. My local water report states I have 8.81 mg Ca/l, which means nothing to me. 

Any thoughts on whether I should add calcium, and if so, how?


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## PARAGUAY (3 Sep 2018)

You could add something like TNC GH boost


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## ian_m (4 Sep 2018)

According to Wikipedia (Hard Water) you water is definitely soft. You 8.8mg/l corresponds to about 0.5dGH.





So it is recommended to buffer it up to 4-8 dKH, especially important if using CO2, so you can set and hold CO2 levels easily. Below 4dGH you will certainly encounter pH swinging issues as the water has limited buffering.

Below is a link on how to make your own re-mineralising mix.
http://www.theplantedtank.co.uk/RO.htm


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## dw1305 (4 Sep 2018)

Hi all, 





Surya said:


> Any thoughts on whether I should add calcium, and if so, how


You can buy food grade <"calcium chloride (CaCl2.2H2O)">, but the easiest option is just to add some calcium carbonate (CaCO3) to the tank.

<"Oyster or Cockle shell chick grit"> or a bit of <"Cuttle "bone""> (sold for budgies) are the cheapest CaCO3 options. <"Aragonite"> (the biogenic form of calcium carbonate) is more soluble than calcite, but powdered limestone (garden lime) would also do.

You don't need to add very much limestone.

cheers Darrel


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## Surya (4 Sep 2018)

Thanks very much for replies!

Thanks for link to RO mix. I already buffer KH to 5 with potassium bicarbonate to keep the pH stable. So just need to sort out GH. A cuttlebone in the filter would bethe easiest option, do you think that would provide enough calcium for plants' needs? My fish are all soft water ones.


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## dw1305 (4 Sep 2018)

Hi all, 





Surya said:


> A cuttlebone in the filter would bethe easiest option, do you think that would provide enough calcium for plants' needs?


Definitely would. 





Surya said:


> My fish are all soft water ones.


Calcium chloride would allow you to control the amount of calcium you added, if you want to carry on using the KHCO3 as a carbonate buffer. Even though it says it is the dihydrate (CaCl2.2H2O) when you buy it, it will always be the hexahydrate (CaCl2.6H2O) when you use it. You need to store the calcium chloride in a sealed container (or the freezer) otherwise it will carry on picking up atmospheric moisture until it "melts".     

If you go with the cuttlebone you can reduce the KHCO3 addition. If you want to breed your fish you probably need low dGH/dKH, but it doesn't matter for as much for their general maintenance. As @ian_m says a bit of dKH makes tank management easier, I'm not a CO2 user, but I cut the rain-water I use for the tanks with a bit of tap water (about 18dKH) when the conductivity gets below about 60 microS.

You can't specifically relate conductivity to hardness, but at 60 microS you don't have many ions of any description. 

cheers Darrel


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## Surya (4 Sep 2018)

Thanks very much. I'll go with cuttlebone (full one in the filter? It's a 240l tank) because it's easily available to me and reduce the potassium bicarb (like halve it do you think?)

Also while the experts are here  - I'm about to start EI dosing tomorrow (APF starter kit bottles all mixed). Will my fish be bothered by the sudden onslaught of ions? Is it OK to go in full whack from day one or build up gradually?


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## micheljq (4 Sep 2018)

If you add calcium better use a GH buffer of some kind, which will also add magnesium and potassium, they are also important for the plants.

There are many products available, like Seachem Equilibrium for example.

Michel.


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## Surya (4 Sep 2018)

micheljq said:


> If you add calcium better use a GH buffer of some kind, which will also add magnesium and potassium, they are also important for the plants.
> 
> There are many products available, like Seachem Equilibrium for example.
> 
> Michel.



Thanks - I'm dosing EI though which seems to have heaps of magnesium and potassium - wouldn't it be overkill to add even more?

I considered equilibrium but a lot of reviews say it's very hard to dissolve.


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## ian_m (4 Sep 2018)

Surya said:


> Thanks - I'm dosing EI though which seems to have heaps of magnesium and potassium - wouldn't it be overkill to add even more?


No. Most people who roll their own dosing schemes based on some theory, some questionable test kit result, some YouTube video or water test result end up with plant issues. There is no downside to having excess Mg and K beyond the EI dose. These need to be in the 1000's ppm before you might encounter any livestock issues, about 10-100 times the EI levels.


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## Surya (12 Sep 2018)

OK so just to be sure - I've added a full cuttlebone to the filter. I plan to replace it with a new one every month when I clean the filter, unless there is loads left. Does this sounds reasonable? I'll continue to buffer up to 5 degrees of KH with potassium bicarbonate though will be conscious I might need less of it with the cuttlebone.


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## Aqua sobriquet (31 Mar 2020)

Just thinking out loud but would crushed egg shells in a bag in the filter work?


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## BarryH (31 Mar 2020)

Following on from a different post yesterday, I called in at my local Pets At Home to pick up a cuttlefish bone. All the bones were packed and sealed on cards and they all looked very "yellow" in colour and were branded Vitapet. Always thought cuttlefish bones were white in colour so I wasn't sure if something may have added to the bone to give the discolouration.

In the finished I ordered from Amazon and they should be here tomorrow.


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