# Soft Water Plants: Low KH, GH, or Both?



## cS (Jan 27, 2004)

These so-called soft-water plants require low KH (carbonate content) or low GH (Ca/Mg content) or both? I keep coming across conflicting references. How low is low?

Thank you.


----------



## Edward (May 25, 2004)

Hi cS

First is the KH. If we keep it low, 1 degree or less, we get the option of lowering pH anywhere we want to. 
The other issue is GH. The GH is made of Ca and Mg as we know, but there are two scenarios. One is CaCO3 / MgCO3 / CaMg(CO3)2 and the other is CaCl2 / CaSO4 / MgSO4. Both give us the same degrees of GH. However, this has enormous effect on plant health, especially on the difficult species.

What is your experience?

Thank you
Edward


----------



## freshreef (May 14, 2004)

Edward said:


> Hi cS
> 
> . One is CaCO3 / MgCO3 / CaMg(CO3)2 and the other is CaCl2 / CaSO4 / MgSO4. Both give us the same degrees of GH. However, this has enormous effect on plant health, especially on the difficult species.


Edward, could u b more specific and explain?


----------



## shalu (Oct 1, 2004)

I guess Edward is saying that the first option also increases KH, which is not desirable in this case?


----------



## Laith (Sep 4, 2004)

I'm pretty sure that references to soft or hard water are about the GH, not the KH.


----------



## Edward (May 25, 2004)

Hi

We can have two aquariums with identical water parameters:
TDS 300uS, 6.3 pH, 4 GH, 2 KH, 20 Ca, 5 Mg and 30 CO2

However, they could still be very different in terms of dissolved minerals. First aquarium can have Ca and Mg based on CO3 carbonates and the second aquarium on chlorides and sulfates. 

#1 aquarium 
CaCO3, MgCO3, CaMg(CO3)2

#2 aquarium
CaCl2, CaSO4, MgSO4, (soda NaHCO3 for KH)


I found many plants reacting to the two diverse environments. The #1 aquarium required more TE and more light then the aquarium #2.

Another experiment was slow mineral concentration increase. Continuous increase of carbonates had negative impact on plant health. On the other hand, chlorides and sulfates caused little problems.

This might be the secret of so called soft water plants. What do you think?

Thank you
Edward


----------



## shalu (Oct 1, 2004)

Edward, sounds like you have more controlled env than most of us do. Please continue the experiment and let us know the long term effects. Are you trying those so called softwater plants?


----------



## BigFoot (Jan 3, 2005)

I too am very interested in this subject.


----------



## plantbrain (Jan 23, 2004)

Low KH plants: eg they grow better, not "required" are Eustralis, Rotala macrandra, R. wallichii. I might be missing one, but I've fairly well explored these over a few years with different routines.

These are the only plants I know that do better in lower KH levels(3-4 Kh or so).

Having gone to GH's of 25 degrees down to 1-2, the Cl, SO4 I agree do not do much, whereas the carbonates appeared to with the above plants.

Adding more NO3 and traces and PO4 resolved the issues for these plants with higher KH's, but not all. 

I had no issues growing any other plants, Tonia or other plants at high KH's and GH's. I lived where the Gh was 25 and KH 11 for 3 years, now I live where it's a KH of 1 and GH of 3. My client's tanks have a KH of 0-1 and a GH of 2- 4. These are raised to a KH of 3 and GH of 5 has seemed to provide the best growth overall for every plant species I've grown but I've not found issue with my present tap either.

I'll top off GH with SeaChem Equilibrium, that seems to do the best job vs CO3's and CaCl2/MgSO4. Otherwise I leave the KH alone. 
Paul Sears had very softwater as well and the lower Fe levels may reflect this trend vs the harder water's need for more trace elements.

I think plants that cannot use bicarb's might have trouble, about 50% of plants can use bicarb(researcher estimations, mosses cannot etc), those that do will grow better in higher KH water as there is more total carbon available. Van et al showed this nicely, DIC levels can be reviewed : Raven 1970, Steemann-Nielsen 1960) and tidbits on soft oligotrophic waters vs richer HCO3 waters. 

Long term limitation of biomass vs short term limitation also plays a role.
(Plant "momentum" as I refer to it sometimes) 

Regards, 
Tom Barr


----------



## Edward (May 25, 2004)

plantbrain said:


> Adding more NO3 and traces and PO4 resolved the issues for these plants with higher KH's, but not all.


 Light intensity is another factor we could add to this list.



> I'll top off GH with SeaChem Equilibrium, that seems to do the best job vs CO3's and CaCl2/MgSO4.


 I have tried CaCl2 & MgSO4 with limited success. The combination of CaCl2, CaSO4 and MgSO4 works the best for me. It has something to do with ionic balance in the water.

Thank you
Edward


----------



## plantbrain (Jan 23, 2004)

Edward said:


> Light intensity is another factor we could add to this list.
> 
> I have tried CaCl2 & MgSO4 with limited success. The combination of CaCl2, CaSO4 and MgSO4 works the best for me. It has something to do with ionic balance in the water.
> 
> ...


Some plants grow nicer with less light and some seem to do better with more. As far as growth rates, generally more light= more growth up to about 1/4-1/3 of full sun, but this assumes the other nutrient needs are being met.

I think adding lots of CaCl2 can cause issues....... perhaps..KCL did not seem to when we added lots in the past. 
I always preferred K2SO4 over KCl.

Likewise CaSO4, is not a bad alternative and somewhat souble. 
I used Ca(NO3)2 for a time also, it's nice and souble.

CaCl2's wide spread use has only recently become popular, the Cl- part is one of those things that folks often discuss but few test independently. Is it significant?

I did well with very high Cl in the tap in southern CA, but did so so with none in SF with Eustralis. Likewise, the reverse was true too, folks added KCl or no Cl and did well in both cases. Perhaps at low levels of Ca/Mg/NO3 etc this Cl- effect is more intense much like adding more traces in harder water.

SO4's have (I) been fairly well explored and I cannot show they hurt at a wide range and high levels. That's from the K2SO4 dosing routines.

Regards, 
Tom Barr


----------



## cS (Jan 27, 2004)

So, if I were to summarize, then:

(1) All plants are indifferent towards high GH.
(2) Most plants are indifferent towards high KH, so long as the pH remains less than 8.
(3) For certain species, moderate-high KH (not GH) affects them negatively.

Are the above three conclusions correct? If so, then I have a few follow-up questions. 



plantbrain said:


> Low KH plants: eg they grow better, not "required" are Eustralis, Rotala macrandra, R. wallichii.


What are the criterions for classifying certain plants as "soft" versus "regular" water plants? I am thinking of _Eusteralis_ (_Pogostemon_) specifically and _Rotala macrandra_ to a lesser degree. Personally, I think that a "mature tank" (one with an established substrate system) plays a much larger role with the "soft water plants" than actual water column KH.


----------



## plantbrain (Jan 23, 2004)

I think generally your notions are correct.
Always an exception though.....

I think mature tanks do play a role but with all plants.
I think this is due to aquatic bacteria and also fungi, somethign seldom talked about in aquatic substrates, out substrates are high in terms of redox, wereas most are very reductive in nature. All the O2 allows for large colonies of fungi and considering all the O2 that roots release into their surroundings, mycorrhizae in aquatic substrates plays a large role in stabilizing the substrate.

A good root structure and thick root growth seems to really help the tank's momentum and given that the O2 is being pumps into it via the roots and the fungi are helping the nutrient cycling, and bacteria.

This is back this up very well with specific research.

I've done several mychorrizal test to see and have found at least 3 species of ectomychorrizae. Bolbitus has it, Blyxa did also.There are others.

Once the Blyxa gets this, then it's much eaiser to grow from then on in the tank. Same with the Bolbitus etc.

Regards, 
Tom Barr

www.BarrReport.com


----------

