# How is it possible that my calsium is 40 ppm on wc and 4 days later it is 55ppm



## xandro007 (11 Jun 2016)

I have lava rocks ada amazonia dragen stone all ada additives.
But they are al inert zo how ist it possible blahblahblahblah my calcium increased
?


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## Julian (11 Jun 2016)

Because your test kit is lying to you.


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## BigTom (11 Jun 2016)

Dragon stone isn't always totally inert, it's probably leaching a bit. 

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## xandro007 (11 Jun 2016)

Julian said:


> Because your test kit is lying to you.


I tested 3 times 3 weeks long


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## xandro007 (11 Jun 2016)

BigTom said:


> Dragon stone isn't always totally inert, it's probably leaching a bit.
> 
> Sent from my HUAWEI GRA-L09 using Tapatalk


How is this possible i have these dragen Stones 3 years in my aquarium


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## alto (12 Jun 2016)

Julian said:


> Because your test kit is lying to you.



What do you think will be interfering with the kit reagents?

The most significant error with test kits is human error
 - when the compound of interest falls within the median range of the kit, accuracy & precision is greatest: at upper ranges, agents involved in the chemical reaction may be limited (just do a half dilution on tank water & repeat test samples), at lowest ranges, human eye tends to be a poor detector of minor color changes (often alternate kits are available or one can "spike" the sample).


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## Straight Shooter (12 Jun 2016)

As water evaporates the calcium will be left behind. If you top up with tap water at this point which contains further calcium, your levels will increase. If you add RO water at this point instead, your levels will balance out again. 

If you only did top ups in aquariums, not water changes, these levels will raise continuously...

Also agree that test kits are pretty rubbish. Don't believe that result at all.. we really need laboratories for such things, not hobby test kits.


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## Straight Shooter (12 Jun 2016)

Straight Shooter said:


> If you only did top ups in aquariums, not water changes, these levels will raise continuously...



Plants will also take up some calcium, some may also be lost to the substrate. In every tank Ca uptake and loss is unique.

I'm saying that in your case, calcium build up may be exceeding plant uptake and other losses leading to slightly higher calcium readings over time.

This may be happening in combination with calcium leaching from rock etc.


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