# Questions about substrates that alter PH / KH



## Paul195 (5 Apr 2016)

Hi

I'm trying to choose the right substrate for my 2nd tank setup. I'm leaning towards a complete substrate because I don't want to go cheap and regret it later.

My tap water is PH 8.2 after resting, KH 11, GH 13. On the Oliver Knott Nature Soil PDF it says :



> - IMPORTANT for customers with hard tap water (from KH12 / GH 18 and more): NatureSoil provides in a natural way that your aquarium water was softer than your source water, few hours after filling. So you have 1-2 days after set up an aquarium water with a KH of about GH 5-7 and 9-12, depending on how hard your tap water is. It also reduces the pH value on the neutral or slightly acidic range (6.8 - 7.0). - If you use softer tap water your aquarium water will stabilise to similar values as when you using hard water (balance the system). But this depends on the hardness of you source water and the frequent of the water change.



Can anyone make sense of this? Am I right in saying that I can expect:
PH 6.8 - 7
KH 5 - 7
GH 9 - 12 ??

My questions..

1) If the substrate alters the parameters of the water, wont this cause a problem for the fish when doing a water change with new water from the tap?

2) When doing water change every week, wont this just bounce the parameters back up again over short period of time?

3) If no to above, how long could I expect the substrate to keep the parameters steady at the lower values? long term ? indefinitely?

4) How does this substrate lower these parameters, and why necessarily should I want a substrate that does this (other than type of fish being kept) ?

5) Will the ADA / Oliver Knott soil substrates stay in their granule form over the long term or will they start to break down eventually?

Any help much appreciated

Cheers
Paul


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## EdwinK (6 Apr 2016)

I never used Knott's substrate but with AS you can expect ph about 6.8, kh about 3-5. 
1. No it wont because you probably will change not more than 50 percent at the time;
2. No it wont;
3. With your source water I would say about from 2 to 3 years;
4. Substrate is able to absorb calcium and magnesium carbonates that's why it has a limited "life span"; You should want these parameters for your plants not fish;
5. AS will brake start to brake down in about 5 years.

Hope it helps


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## Paul195 (6 Apr 2016)

Hi Edwin

Yes this helps, thanks for answering those questions. With my hard source water, how important is it to lower my parameters to these values for the plants to thrive ? If I were to use a substrate that doesn't alter water parameters, would I be at a disadvantage ?

Thanks again

Paul


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## alanchown (6 Apr 2016)

I'm using JBL Proscape soil with CO2. Its been in a year, my KH is now around 8, but my GH seems to vary between 14 and 20- but may depend on how close it is to my weekly water change. I'm sure both KH and GH has crept up over the year. London tap water.


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## dw1305 (6 Apr 2016)

Hi all,





Paul195 said:


> With my hard source water, how important is it to lower my parameters to these values for the plants to thrive ? If I were to use a substrate that doesn't alter water parameters, would I be at a disadvantage ?


Most plants will be fine, and some (_Cryptocoryne crispatulata_, _Vallisneria_ spp., _Hygrophila corymbosa, Ceratophyllum demersum, Najas guadalupensis, Pogostemon helferi_) do better in harder water. 

A lot of member like "ian_m", "Troi" and "Akwascape" have hard water. Have a look at _<"Cryptocoryne parva_ carpet">. 

cheers Darrel


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## EdwinK (6 Apr 2016)

As Darrel says most plants will do just fine in your water although if you are thinking of CO2 system it may be hard to reach the desired levels due to poorer CO2 dissolvency. In my smaller tank kh is around 20-25, gh around 30, no CO2 and plants are growing well.


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## Paul195 (6 Apr 2016)

EdwinK said:


> if you are thinking of CO2 system it may be hard to reach the desired levels due to poorer CO2 dissolvency



Yes I have already purchased all the equipment to run C02 on the tank. Based on this, do you think it would be a good choice to use a substrate that lowers the KH so my C02 would go further / it would be easier to reach 25-30ppm? 

One answer usually ends up with three more questions when a novice trying to learn in this game!

Cheers
Paul


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## EdwinK (6 Apr 2016)

Yes it would be a good choice. I assume your purchase of CO2 system states that plants will be the top priority. If so, AS (or similar substrate) is good not only for lowering kH but for releasing and storing nutrients.


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## Paul195 (6 Apr 2016)

EdwinK said:


> I assume your purchase of CO2 system states that plants will be the top priority.



It will be a planted community tank, and fish and plants are equal priority to me.

My main concern with using a substrate which alters water chemistry is that although I am very keen, I am still only a beginner and I don't want to make my life difficult in the short or long term by using really advanced products and/or techniques before knowing the basics....well actually, I know the basics because I have done loads (probably way too much) of research, its just I dont have much practical experience with these principles. My first tank was a JI dirt tank capped with moler clay. It was an algae ridden disaster which I believe was related to having very low light and no C02, hence why I have invested in the pressurised C02 system and 4x39W T5 luminaire this time round (will probably only use 2x39W T5's). I will post up some pictures of my tank, light and DIY stand tomorrow at some point which is almost ready 

Paul


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## EdwinK (7 Apr 2016)

Well it's difficult for a beginner to sort out the right information especially when there are lot of methods for tank setup and maintenance. AS is advanced product only for nutrient buffer which in most cases corrects the fertilizing mistakes you make.


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## Paul195 (7 Apr 2016)

Thanks for your advice  
I have just made an order for 20L of the black Oliver Knott Nature Soil.  

As mentioned, here are the pics of my new tank, light and DIY stand. Ready to start scaping over the next few weeks and very excited 




 

 

Cheers

Paul


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## zozo (10 Apr 2016)

I also have my questions and rather a bit of doubts in this KH and ph altering properties of branded soils..  I never used them, only have experience with Akadama and here also it is stated it reduces kh and lowers ph, both actualy go a bit hand in had because both values are kinda related to eachoter.. Anyway i noticed it doing that, but this is not for a long term proces.. At one point it is realy done with lowering these values, at least that's what it does in my case.. I guess this also goes for any other branded soil as well. But behold it's a educated guess, but i do not know of anything that is able to lower thos values for ever till the end of time. like ADA contains humic acids doing this, which could be compared with using peat, does the same lower kh and lower ph but not for ever, at one point it's done. SO if you want to keep this stable yu have to keep adding peat or else you just go back to tap water values..

If somebody can explain why and how this would work otherwise and be constant with these type of soil.. I realy like to know.. But for now i got big ?? and rather believe it's a marketing yell to make it sell. 

And as Darrel says, these values don't have to be a problem, just choose plants which are known to handle it.

You might find this thread an intresting read.. 
http://www.ukaps.org/forum/threads/whats-the-importance-of-kh.31225/


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## dw1305 (10 Apr 2016)

Hi all, 





zozo said:


> If somebody can explain why and how this would work otherwise and be constant with these type of soil..


 Akadama and sphagnum peat I can do, and I would assume that most of the other active substrates are the same. I'll deal with cation exchange capacity (CEC),  but active substances will also have anion exchange capacity. 

In the cases of <"Akadama"> (and sphagnum peat) they come from areas of high rain-fall and all the cation exchange sites are initially filled with H+ ions, which are exchanges for more strongly bound multivalent cations, depending upon their valency and abundance in the tank water. The pH we measure is a the ratio of H+:O-H ions, so when we exchange H+ ions for alkali or alkali base metals we reduce pH. <"Fulvic and humic"> compounds may also act as be the H+ ion donors in substances that cause water tinting.



 

Because it is "cation exchange" they will only soften the tank water until the H+ ions have been replaced by more strongly bound ions. Removing the strongly bound cations is more problematic, and would either involve acid washing, or many years of leaching in rain-water.

cheers Darrel


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## zozo (10 Apr 2016)

dw1305 said:


> Hi all,  Akadama and sphagnum peat I can do, and I would assume that most of the other active substrates are the same. I'll deal with cation exchange capacity (CEC),  but active substances will also have anion exchange capacity.
> 
> In the cases of <"Akadama"> (and sphagnum peat) they come from areas of high rain-fall and all the cation exchange sites are initially filled with H+ ions, which are exchanges for more strongly bound multivalent cations, depending upon their valency and abundance in the tank water. The pH we measure is a the ratio of H+:O-H ions, so when we exchange H+ ions for alkali or alkali base metals we reduce pH. <"Fulvic and humic"> compounds may also act as be the H+ ion donors in substances that cause water tinting.
> 
> ...



Thanks Darrel, this process i'll understand, but as i experience like Akadama and or peat will exhaust at one point and not alter the desired values anymore.
And then you just have to deal again with what comes from the tap.. Like in both tanks i used akadama it altered these values for a few weeks and that was the end of it.
So i can't believe that those expensive branded substrates keep doing this for ever and never exhaust.. And what the point is of having and advertising with this property if it only is temporary?


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## dw1305 (10 Apr 2016)

Hi all,





zozo said:


> And then you just have to deal again with what comes from the tap.. Like in both tanks i used akadama it altered these values for a few weeks and that was the end of it.


Yes, it is ion exchange. If you have water with a high dGH then Ca++ etc ions will fill the exchange sites pretty quickly. 

The first lot of moler clay based cat litter I bought I soaked in tap water (about 18dKH, nearly all as Ca++ and HCO3-) and it still raises pH, even after several years of use with rain-water. The next lot I just let sit outside in the rain for 6 months, and that remained "active" for about 18 months (again changes with ran-water, but our rain-water has some carbonate buffering). 





zozo said:


> So i can't believe that those expensive branded substrates keep doing this for ever and never exhaust.. And what the point is of having and advertising with this property if it only is temporary?


They will inevitably stop working, at that point I think they idea is that you go and buy some more active substrate. 

cheers Darrel


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## zozo (10 Apr 2016)

dw1305 said:


> Hi all,Yes, it is ion exchange. If you have water with a high dGH then Ca++ etc ions will fill the exchange sites pretty quickly.
> 
> The first lot of moler clay based cat litter I bought I soaked in tap water (about 18dKH, nearly all as Ca++ and HCO3-) and it still raises pH, even after several years of use with rain-water. The next lot I just let sit outside in the rain for 6 months, and that remained "active" for about 18 months (again changes with ran-water, but our rain-water has some carbonate buffering). They will inevitably stop working, at that point I think they idea is that you go and buy some more active substrate.
> 
> cheers Darrel



That's remarkebly long, didn't expect that.. I got Gh7 and Kh7 with a Ph 7.8 from the tap stable  Ph8 after a few hours. I do not know for how long precise but the Akadame lowered the Ph to 6.8 for a while and went indeed rather quickly back to Ph 8. So for these properties i do not have to buy it.. But it also still all grows with these values in low tech. Have no issues with it and see no reason to change it with chemicals or other additions.


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