Do plants struggle with nutrients in hard water?

[Doc_Ho11iday]

45 Gallon. Set up 10/2022.

30 Nitrate. 0 Nitrite. 0 Ammonia. GH 300. PH 7.4. KH 120. 
No CO2. Medium light.

I have 4 Crypts, 2 swords, 1 Anubias, 1 Java fern, 1 Pogo and some Java moss. The Pogo is growing like crazy. The crypts are decent and fed ACO root tabs often. The swords are barely hanging on even though they get easy green and root tabs. I got them from LFS who claimed they were Brazil Swords. 
 

I was reading that plants can’t absorb as many nutrients when the water is super hard. Any truth to that? 

[CJs Aquatics]

I’ll preface by saying this is not based on scientific evidence but only years of experience growing plants in my own hard water. My educated guess would say they probably have a harder time with it, however I would follow that up by saying it’s been negligible for me. They grow like crazy when there specific needs are catered too regardless of the water. Root feeders need a ton of nutrients at the roots, column feeders benefit from nutrients dosed in the water, and there’s “almost” no such thing as enough light for most of the plants you listed. I would focus on dialing in the nutrients and lighting rather then remanufacturing the water itself. There’s always going to be plants we struggle with but lastly bc you mentioned it, my swords were days away from death, I all but gave up, then I pulled them, planted them in pots with dirt and clay based substrate capped with sand, and now they easily fill up a 40 gallon they are so big, so small adjustments can yield large results, I hope this helps.

[nabokovfan87]

My water is generally very, very hard water with mid-low KH.  Sometimes KH was higher for me and stable (100+) and now it's about 40 out of the tap.

That being said, I read the title as "can plant struggle in..."

I wanted to preface my response with an example in this thread specifically talking about iron deficiencies.

I think plants very much can struggle in hard water just like they can struggle in soft water and in some tanks where an experienced hobbyist is doing something like EI dosing.

The most common issues you're going to run into is trying to find out what minerals are in the water and what aren't.  That means there are test kits where you want to find out specific key nutrients plants commonly are missing and be able to thoroughly analyze your water.  Once you have that, then you can progress and diagnose issues.

[knee]

On 2/12/2023 at 8:56 PM, Doc_Ho11iday said:

45 Gallon. Set up 10/2022.

30 Nitrate. 0 Nitrite. 0 Ammonia. GH 300. PH 7.4. KH 120. 
No CO2. Medium light.

I have 4 Crypts, 2 swords, 1 Anubias, 1 Java fern, 1 Pogo and some Java moss. The Pogo is growing like crazy. The crypts are decent and fed ACO root tabs often. The swords are barely hanging on even though they get easy green and root tabs. I got them from LFS who claimed they were Brazil Swords. 
 

I was reading that plants can’t absorb as many nutrients when the water is super hard. Any truth to that? 

It's the PH that you need to worry about when it comes to aquatic plants. PH is important for plants because if affects whether or not important nutrients can dissolve into the water column. Hard water water itself is not bad for plants. What plants have difficulty with is a high pH, which is caused by a high concentration of carbonate hardness (KH). 

[Phoenix1391]

I have horribly hard tap water. Over 400 ppm. I have very successfully kept crypt, and anubias. The Java fern and moss do ok. Haven’t kept the swords in my hard water tanks though. But yeah some plants definitely have a hard time with suuuper hard water like that. Partly why I have separate tanks that are either hard tap water or RO water.

[Tanked]

Minus the fern and moss, I have the same plants and 300+ GH. 40 kh. and 6.4-6.6 ph. I don't think the hardwater is the issue. Some plants don't grow in some of the tanks, and do well in others.  All of the tanks share the same water.  The primary differences between the different tanks are the lighting and nutrient levels.