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Hard water and plants- a problem?


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On 2/4/2022 at 1:59 PM, BAT said:

I have noticed a lot of posting about hard water and plants. I have very hard water- >180 on the AC strips. 

what should I be on the lookout for in my planted tank?

Depends on the species.

On 2/4/2022 at 4:27 PM, Greg Stewart said:

Depends on the plant. Lots of species do very well in really hard water, others not so much.

Came here to say this.

Some plants do just fine in hard water, some don’t really care, some do better in soft water.  For instance, there are Crypts that have notable preferences for one or the other but most will tolerate either.  If you have a specific plant you’re interested in or concerned about, do some reading, but make sure to consult multiple sites.  If the wording is too similar, keep in mind there’s a lot of copy paste out there so you may be getting only one person’s opinion repeated many times over.  Try to find actual source material as much as possible.  The Crypts Pages is an excellent source I’ve found for information specific to crypts, for example.


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Mine is so hard it’s a violent magenta pink violet color. Api test I’m over the chart by a few drops as well. It means great growth happy plants. I have no issues I don’t fertilize or root tab or co2. Occasional potassium and phosphate deficiency but water changes and feeding veggies usually fix that. Depending on you stock nitrates my fall I have nitrate in my water as well plus high stock so I don’t deal with that one. 

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I'm ORD, and everyone already gave you great advice.

I will add that the biggest potential for an issue is if almost all your hardness is due to calcium, and your plants don't get enough magnesium, potassium or some other mineral. Then you will see a specific mineral deficiency.


Plant growth is determined by whatever nutrient is in least supply.

Nutrients include carbon (CO2), oxygen, nutrients, water (H2O),  minerals, and light.

Nitrogen can be utilized by plants in its ammonia, nitrite, & nitrate form.

The reason there's no single 'right' answer, is because growth is determined by the interplay between macronutrients, micronutrients, light / photoperiods, minerals and gases. 

You can have 10 different people with hardness greater than 180, all growing the exact same plants with the exact same fish in the exact same size aquarium with the exact same lights, and still get different variations of growth due to differences of minerals in the water that give the 180.

Majority of plants will be thrilled with hardwater, some will not be thrilled depending on what dissolved solids are giving your water its hardness.

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