# In your opinion, what affects how long buffering substrate lasts?



## Luciferene (Feb 7, 2018)

So factors like pH, GH, KH, TDS, etc what would affect buffering soil to be exhausted?

Also, would having a separate bucket to buffer your water before adding it to your shrimp tank help with how long the buffering substrate in the shrimp tank can last?

Any kind of experiences, thoughts, theories would be great. Thanks


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## madcrafted (Dec 23, 2017)

Carbonates, whether from your tap or other source in your tank like rocks and whatever you might cram in that filter tray.


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## chanceofplants (Mar 21, 2018)

It's basically how much it has to work to buffer the ph of your water. So if you're adding water that has a really high ph, the soil has to work harder to buffer it down to the right ph. As it does this, it'll lose it's buffering capacity.


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## jeffkrol (Jun 5, 2013)

> Soil pH change depends on initial pH, net inputs of acid or alkali, and the
> soil’s pH buffering capacity (pHBC). Soil pHBC is governed
> mostly by protonation/deprotonation of acidic groups on organic
> matter, oxides, and hydroxides; dissolution/precipitation
> ...




Longer version.............


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## Zoidburg (Mar 8, 2016)

Fluval Stratum often gets the reputation for having the shortest period of time that it buffers the water... it's also one of the cheapest buffering substrates out there.


Other substrates often buffer for longer periods of time.


So quality of product can also play a role.


However, the difference in how long they buffer could potentially only be a few months difference... but some people have reported some substrates (not Fluval!) for up to 5 years with a lower pH. Once a substrate stops buffering, the pH generally rises.


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## Luciferene (Feb 7, 2018)

@madcrafted So if carbonates are the key buffered ions, you think GH is not affected by buffering substrate?
@chanceofplants I was thinking it wasn't as simple as high pH. Since I could have 8.0 pH water with relatively low KH and very high KH. I imagine the latter will exhaust the soil faster.
@jeffkrol I have a feeling this has lots of info I'm looking for, thanks. I'll mine through it when I have some time to sit down and read it through.
@Zoidburg I meant given same substrate what's the chemistry behind buffering substrate, though I heard all about how FSS is cheaper short lasting substrate. And wow 5 year? I wonder how that came to be since it feels like most people use remineralized RO which should keep everyone's buffering substrate last around the same length. Maybe the frequency of waterchanges?

This question just came up to my mind since a friend of mine has ADA Amazonia in his tank and he uses tap water not RO. And the substrate is still buffering about 1.5 years since it started. Tap in my city is pretty consistently around 8.0 pH, 5 KH, 7GH and 120-130 TDS. So I was thinking despite the high pH, our tap is pretty soft so the substrate is not exhausted as fast.


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## Zoidburg (Mar 8, 2016)

The more carbonates/bicarbonates (KH) that are in the water, the more the soil has to work to buffer the pH down and absorb the carbonates/bicarbonates, the less amount of time it will last. A simplistic explanation.

Having soft water certainly helps to have the soil last longer, although it's still not recommended to add KH in a tank with a buffering substrate.



More 'complicated' version....

http://www.plantedtank.net/forums/2...n-low-cec-inert-cation-exchange-capacity.html


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## Luciferene (Feb 7, 2018)

Interesting read, I think I came across it in the past and it flew by my head then.

So what I understand is, aquasoil affects KH and pH and not GH, fair to say?


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## natemcnutty (May 26, 2016)

Luciferene said:


> Interesting read, I think I came across it in the past and it flew by my head then.
> 
> So what I understand is, aquasoil affects KH and pH and not GH, fair to say?


That is mostly correct. The affect on GH is so minute that it isn't of concern - most don't affect Ca++ or Mg++ at all though some will pull Fe++ and possibly Mn++ from the water column. Those are such small contributors that you wouldn't notice them anyway.


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## Luciferene (Feb 7, 2018)

natemcnutty said:


> That is mostly correct. The affect on GH is so minute that it isn't of concern - most don't affect Ca++ or Mg++ at all though some will pull Fe++ and possibly Mn++ from the water column. Those are such small contributors that you wouldn't notice them anyway.


Minute effect is mostly at the beginning of setting the tank up with the soil 'charging up' right? Ca2+ and Mg2+ seems to be the main concern with shrimps anyways.


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## natemcnutty (May 26, 2016)

Luciferene said:


> Minute effect is mostly at the beginning of setting the tank up with the soil 'charging up' right? Ca2+ and Mg2+ seems to be the main concern with shrimps anyways.


Many soils already have good iron content (such as Aquasoil), but over time (as far as I know), they can absorb lost nutrients as they are taken up by roots or released into the water column.


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## Luciferene (Feb 7, 2018)

Gotcha. If they reabsorb the nutrients, with regular water column dosing do the substrates not need to be replaced? If one's desire was to just keep plants and not worry about buffering capacity.


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## natemcnutty (May 26, 2016)

Luciferene said:


> Gotcha. If they reabsorb the nutrients, with regular water column dosing do the substrates not need to be replaced? If one's desire was to just keep plants and not worry about buffering capacity.


They eventually break down and stop being able to absorb nutrients. If you wanted to do more research about it, the term is Cation Exchange Capacity.

I know @Seattle_Aquarist uses Safe-T-Sorb (calcined clay) and has recently been talking about his being exhausted. He'd have good feedback on that. Unfortunately, I don't have any hands on experience with anything but Aquasoil at this point, and mine is still buffering and working properly.


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## Luciferene (Feb 7, 2018)

Thanks, I've read about CEC in the link Zoidburg posted but didn't realize that it was the same concept.

Just out of curiosity, how long has your Aquasoil been buffering for?

If I remember correctly @Seattle_Aquarist had his tank set up for quite a few years which seems long enough for me. And within my knowledge, anything out in the market, besides inert low CEC substrates like BDBS, lasts virtually forever anyways.


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## Seattle_Aquarist (Jun 15, 2008)

Hi All,

Because of the very soft water locally I try to shorten the 'buffering' time of STS (Safe-t-sorb) in my tanks by adding NaHCO3 (bicarbonate of soda / aka baking soda) to my tanks until the buffering capacity of the substrate subsides. Even when I do this it takes about 4 months to substantially stop the buffering capacity. The cation exchange capacity seems to last for two - three years before it drops off.


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## natemcnutty (May 26, 2016)

My Amazonia is about a year old, and I've only ever done RO with GH minerals in it. Probably 3-4" deep in a custom 10 gallon shallow rimless tank.


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## Luciferene (Feb 7, 2018)

@Seattle_Aquarist Thanks for the feedback. Was there a reason why higher dosage of baking soda couldn't be used to speed up the process?
@natemcnutty How low does your pH gets buffered to? 3-4 inch in shallow tank seems like a lot of substrate compared to water volume.


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## natemcnutty (May 26, 2016)

Luciferene said:


> @Seattle_Aquarist Thanks for the feedback. Was there a reason why higher dosage of baking soda couldn't be used to speed up the process?
> 
> @natemcnutty How low does your pH gets buffered to? 3-4 inch in shallow tank seems like a lot of substrate compared to water volume.


Consistently at 6.4 or so in that tank. And you were right, it's actually 2-3" depending on where. Thought it was deeper 

Not the best picture, but you get the idea.


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## dukydaf (Dec 27, 2004)

natemcnutty said:


> They eventually break down and stop being able to absorb nutrients. If you wanted to do more research about it, the term is Cation Exchange Capacity.





Zoidburg said:


> The more carbonates/bicarbonates (KH) that are in the water, the more the soil has to work to buffer the pH down and absorb the carbonates/bicarbonates, the less amount of time it will last. A simplistic explanation.


So far it seems clear that carbonates and bicarbonates will influence the outcome. 

In the light of the definitions below, maybe the members( not limited to the 2 quotes above) who make reference to the soil absorbing carbonates and the CEC capacity would like to clarify how do these influence the KH?

CEC - cation exchange capacity
Cation - positively charged ion like Ca2+
Carbonate - (CO3)2-
Bicarbonate - (HCO3)-


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## Luciferene (Feb 7, 2018)

@natemcnutty That's a 10G? What're the dimensions of that beauty? It looks at least 20+ in the photo the way it's so long. 

@dukydaf KH just means carbonate hardness, which accounts for carbonate and bicarbonate ions in water. High dissolved cations have no direct relation to KH and some cations like calcium ion will be picked up by GH testing. However, there can be cases where high cation, like Ca2+, can be an indicator of high KH. For example, if you are using aragonite, which contains calcium carbonate, in your tank, it'll raise both calcium and carbonate ions.

That's the 2cents I can give.


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## natemcnutty (May 26, 2016)

Luciferene said:


> @natemcnutty That's a 10G? What're the dimensions of that beauty? It looks at least 20+ in the photo the way it's so long.
> 
> @dukydaf KH just means carbonate hardness, which accounts for carbonate and bicarbonate ions in water. High dissolved cations have no direct relation to KH and some cations like calcium ion will be picked up by GH testing. However, there can be cases where high cation, like Ca2+, can be an indicator of high KH. For example, if you are using aragonite, which contains calcium carbonate, in your tank, it'll raise both calcium and carbonate ions.
> 
> That's the 2cents I can give.


Thanks! It's roughly 24" wide x 12" deep x 8" high, and it's probably the camera angle making it look longer than it is . It was brought over from Japan by someone I met locally, and I fell in love with the bevelled edges all around it. 

You can ignore @dukydaf's question btw. He already knows the answer... History has shown he'd rather play games and point out people's wrong views of things rather than explaining them from the beginning. Not sure if it's too motivate people to do research or to feed an ego, but I feel the same about people doing this as I do when my child leaves a floater in the bathtub - funny as hell but also annoying. 
@dukydaf, I'm always up for learning, so have fun tearing this apart, but I don't think anyone said CEC and buffering capacity were there same thing. It was said that carbonates affect the buffering capacity while I stated the CEC capabilities seem to wear out over time referencing what Roy has been talking about in another thread.

I'm sure I'm totally misunderstanding what I've read, but I was under the impression that Aquasoil is mostly clay, peat, and some form of black magic for good measure, and that clay based soils tend to draw in iron. I don't know if that is part of the way CEC works or some other mechanism. I'm a InfoSec guy, not an organic chemist, so I'm sure most of this is wrong... But here it goes.

From what I've read, most soils we use are negatively charged, so they draw cations to balance out. As those are taken up by plants, they continue to balance out by drawing from the water column. What I don't know if if this capability depletes over time similar to how a battery stops holding a charge over time?

The buffering capacity to bring it to a lower pH is probably due to the peat? As I understand it, peat has a very low pH, so the carbonates would strip the H+ ions from the peat. What I don't know is why it stops at a specific pH such as 6.6 and never goes lower but can take 8.0 pH water and reduce it to 6.6 over and over and over until it is finally exhausted.


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## Seattle_Aquarist (Jun 15, 2008)

Luciferene said:


> @Seattle_Aquarist Thanks for the feedback. Was there a reason why higher dosage of baking soda couldn't be used to speed up the process?


Hi Luciferene,

I could have upped the dosing level and decreased the time but I had fish in the tank and didn't want to risk pH shock.


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## dukydaf (Dec 27, 2004)

Luciferene said:


> @natemcnutty
> @dukydaf KH just means carbonate hardness, which accounts for carbonate and bicarbonate ions in water. High dissolved cations have no direct relation to KH and some cations like calcium ion will be picked up by GH testing. However, there can be cases where high cation, like Ca2+, can be an indicator of high KH. For example, if you are using aragonite, which contains calcium carbonate, in your tank, it'll raise both calcium and carbonate ions.


Thanks for your answer. I was confused because it seems that people started talking about substrates with high CEC, CEC and nutrient absorption and your original question / title of the thread was about buffering substrate. 

So that there is no necessary link between GH and KH is clear. After all you can use CaCl2 and MgCl2 to get your GH up in the clouds and have 0 KH. But to my knowledge most substrates which have high buffering capacity also have good CEC. So I wondered if they have the knowledge to link the two together since they were speaking about CEC and absorption.



natemcnutty said:


> You can ignore @dukydaf's question btw. He already knows the answer... History has shown he'd rather play games and point out people's wrong views of things rather than explaining them from the beginning. Not sure if it's too motivate people to do research or to feed an ego, but I feel the same about people doing this as I do when my child leaves a floater in the bathtub - funny as hell but also annoying.


I don't know man, reading a lot of judgement and anger in your post. I'll look over it and blame it on the political climate where you are. Don't let it affect your enjoyment of the hobby and helping members of this community.

But glad you decided to answer. If your answer to my questions helps me and others to understand how it works, you gain credit points and the community wins. If my question made you critically review what you know and revealed a place where you weren't sure, made you research old topics and read on the subject you also gained better understanding. So, yeah I do real damage to this community. 

I never claimed to posses all knowledge of anything, and there is always new understanding and information published. In this light I asked perhaps there is indeed a link between CEC and buffering ? Why are substrates which have high CEC also capable of high buffering ?



natemcnutty said:


> @dukydaf
> From what I've read, most soils we use are negatively charged, so they draw cations to balance out. As those are taken up by plants, they continue to balance out by drawing from the water column. What I don't know if if this capability depletes over time similar to how a battery stops holding a charge over time?
> 
> The buffering capacity to bring it to a lower pH is probably due to the peat? As I understand it, peat has a very low pH, so the carbonates would strip the H+ ions from the peat. What I don't know is why it stops at a specific pH such as 6.6 and never goes lower but can take 8.0 pH water and reduce it to 6.6 over and over and over until it is finally exhausted.


That is pretty much how I understand CEC as well. Perhaps the "battery" gets filled up with junk like Na+ and maybe the lenght of time it take to deplete the "battery" of the good stuff is also somehow linked to the how deep the substrate is and how large the grains are. I am thinking, that less water flows through deep substrate so it will take longer to "use up the juice" and it takes longer for nutrients to travel from inside the grain to outside. 

So it also reduces the pH to 6.6 independent of KH ? The ability to stabilize at 6.6 and not go lower might have to do with the acids it is releasing and in the absence of extra HCO3- it will not release more at that equilibrium pH. This may be similar (but the inverse) to how CaCO3 is able to increase water pH above 9 when gas exchange is restricted but will again stabilize at 8.3 once exposed to atmospheric air.


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## natemcnutty (May 26, 2016)

dukydaf said:


> Thanks for your answer. I was confused because it seems that people started talking about substrates with high CEC, CEC and nutrient absorption and your original question / title of the thread was about buffering substrate.


Sorry @dukydaf, that was me responding to his question about Amazonia specifically affecting GH. In my experience, it does not (and if it did, people wouldn't use it to keep shrimp). What I have heard of is due to it's clay composition, it does draw Fe from the water. I don't know if that is a function of CEC or if that is something else, but removal of Fe++ should not affect GH in a significant enough way - that's what I was trying to say.



dukydaf said:


> I don't know man, reading a lot of judgement and anger in your post. I'll look over it and blame it on the political climate where you are. Don't let it affect your enjoyment of the hobby and helping members of this community.


Not so much anger but judgement, yes, and I'm sorry for that. Based on things you've posted previously and how you phrased the question, I was convinced you knew the answer and were playing games again (most recent example in the micro traces thread). I jumped to the conclusion that you were trying to make a point, so sorry I attacked you and derailed the thread over that 



dukydaf said:


> But glad you decided to answer. If your answer to my questions helps me and others to understand how it works, you gain credit points and the community wins. If my question made you critically review what you know and revealed a place where you weren't sure, made you research old topics and read on the subject you also gained better understanding. So, yeah I do real damage to this community.
> 
> I never claimed to posses all knowledge of anything, and there is always new understanding and information published. In this light I asked perhaps there is indeed a link between CEC and buffering ? Why are substrates which have high CEC also capable of high buffering ?
> 
> ...


This is probably totally off, but here's a few thoughts that pop into my head based on what I've read.

As to the link between CEC and buffering, I don't think there is a correlation. Aragonite sand and crushed coral are technically buffering substrates, but I believe they have low CEC. The peat/clay based buffering substrates that bring the pH down may have good CEC simply because of their organic content and composition?

For the wearing out of the CEC, what I do know is the manufacturing process leaves the soil with a net negative charge so that it can pull cations. I've had magnets that seem to wear out over time, and I'd assume it's for the same reason that the soil wears out over time. The constant attraction and release of ions probably wears it out similar to how a battery's anode and cathodes degrade over time. 

For the wearing out of the buffering capability, my best guess is that peat, being extremely acidic, is being stripped of H+ as higher pH water is being added. I know that adding KH increases pH, so carbonates may just be bad for the buffering part because of that? I tried reading through this, but I understand maybe 30% of it... A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH by Randy Holmes-Farley - Reefkeeping.com

I also read that these soils are created in a buffer solution and that they use ammonium as a base exchanger cation. Again, I don't understand most of this: https://en.wikipedia.org/wiki/Buffer_solution


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## Luciferene (Feb 7, 2018)

dukydaf said:


> Thanks for your answer. I was confused because it seems that people started talking about substrates with high CEC, CEC and nutrient absorption and your original question / title of the thread was about buffering substrate.


No problem. I believe the topic was brought on because I asked about the effect on GH by buffering substrate. Maybe the term active substrate was more appropriate because the substrate does more than buffering. 



dukydaf said:


> So that there is no necessary link between GH and KH is clear. After all you can use CaCl2 and MgCl2 to get your GH up in the clouds and have 0 KH. But to my knowledge most substrates which have high buffering capacity also have good CEC. So I wondered if they have the knowledge to link the two together since they were speaking about CEC and absorption.


As @natemcnutty eluded to, it may be because buffering substrate in our hobby tends to be ones for plants. And those high nutrient containing substrates for plants tend to be high in CEC. Now I don't know much about this topic, but in my opinion, it could be one of those cases where correlation doesn't necessarily mean causation.



dukydaf said:


> So it also reduces the pH to 6.6 independent of KH ? The ability to stabilize at 6.6 and not go lower might have to do with the acids it is releasing and in the absence of extra HCO3- it will not release more at that equilibrium pH. This may be similar (but the inverse) to how CaCO3 is able to increase water pH above 9 when gas exchange is restricted but will again stabilize at 8.3 once exposed to atmospheric air.


The pH that active substrate stabilizes to seems to depend on the brand, amount of substrate used, etc. Sometimes the same substrate used for different tanks will result in different pH, reasons for which I'm not sure of. But once it buffers to a certain pH in a specific tank, it seems to stay the same until exhausted.

Substrate like Amazonia have soil pH of below 6 and contains humic acid. It seems that's the reason why the pH stabilizes somewhere closer to that area. Similar to CaCO3, as you have mentioned.



natemcnutty said:


> For the wearing out of the buffering capability, my best guess is that peat, being extremely acidic, is being stripped of H+ as higher pH water is being added. I know that adding KH increases pH, so carbonates may just be bad for the buffering part because of that? I tried reading through this, but I understand maybe 30% of it... A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH by Randy Holmes-Farley - Reefkeeping.com
> 
> I also read that these soils are created in a buffer solution and that they use ammonium as a base exchanger cation. Again, I don't understand most of this: https://en.wikipedia.org/wiki/Buffer_solution


If I can brush up on my old chem knowledge, equilibrium equation for KH buffering is: HCO3- + H+ <=> H2CO3 <=> H20 + CO2, where the CO2 just gets gassed off with surface agitation. I'm not exactly sure what triggers exchange to stop but as @dukydaf mentioned this equilibrium equation balances out little higher than 8.3 pH.

Now with that said, with Seachem's product it's apparently possible to maintain low pH while raising KH value, mechanisms for which I'm not sure of.
Raise Carbonate hardness? - Seachem Support Forums


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## dukydaf (Dec 27, 2004)

natemcnutty said:


> Sorry @dukydaf
> Not so much anger but judgement, yes, and I'm sorry for that. Based on things you've posted previously and how you phrased the question, I was convinced you knew the answer and were playing games again (most recent example in the micro traces thread). I jumped to the conclusion that you were trying to make a point, so sorry I attacked you and derailed the thread over that


All is fine, I do not hold personal grudges.... If you want to discuss what/why I did that, hit me up with a PM, no need to say more here. 



natemcnutty said:


> As to the link between CEC and buffering, I don't think there is a correlation. Aragonite sand and crushed coral are technically buffering substrates, but I believe they have low CEC. The peat/clay based buffering substrates that bring the pH down may have good CEC simply because of their organic content and composition?


True but that is alkaline buffering, mainly due to CO3-- and HCO3- present in corals and -OH in liquid buffers(mainly from NaOH). That is simple compared to the interesting things released by our substrates for acid buffering :grin2:


natemcnutty said:


> For the wearing out of the CEC, what I do know is the manufacturing process leaves the soil with a net negative charge so that it can pull cations. I've had magnets that seem to wear out over time, and I'd assume it's for the same reason that the soil wears out over time. The constant attraction and release of ions probably wears it out similar to how a battery's anode and cathodes degrade over time.


So if I understand you correctly, the molecular structure of the substrates actually degrades meaning that not so many partial negative charges are exposed so not as many cations can bind. I guess it could be both... probably very fine testing equipment would be necessary to be able to tell the 2 apart.



natemcnutty said:


> For the wearing out of the buffering capability, my best guess is that peat, being extremely acidic, is being stripped of H+ as higher pH water is being added. I know that adding KH increases pH, so carbonates may just be bad for the buffering part because of that? I tried reading through this, but I understand maybe 30% of it... A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH by Randy Holmes-Farley - Reefkeeping.com





Luciferene said:


> As @natemcnutty eluded to, it may be because buffering substrate in our hobby tends to be ones for plants. And those high nutrient containing substrates for plants tend to be high in CEC. Now I don't know much about this topic, but in my opinion, it could be one of those cases where correlation doesn't necessarily mean causation.



What you @natemcnutty and @Luciferene said, made me think that maybe (wild guess here) the following happens : 
CEC needs many partial negative charges on the substrate surface. Sometimes, molecules do not have very firm grasps on H+ atoms, especially when they are in large constructs where other partial forces are able to compensate for the loss of a + charge. A loss of a positive charge however charges the substrate with a negative one, creating its ability to attract (small)cations like Fe++, ... . On the other hand, more H+ in solution means lower pH. Could this be the link between CEC and acid buffering or more like chemistry pipe dream ? Just to clarify it does not have to be H+ alone, larger acids may act similarly. 

Thanks for the link, by the way. Well written and pretty much what I need for another post. 



Luciferene said:


> The pH that active substrate stabilizes to seems to depend on the brand, amount of substrate used, etc. Sometimes the same substrate used for different tanks will result in different pH, reasons for which I'm not sure of. But once it buffers to a certain pH in a specific tank, it seems to stay the same until exhausted.


You make me curious but I already have enough testing projects for this summer :crying:


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## Deanna (Feb 15, 2017)

I realize that this is heresy to those that stand by high CEC and/or buffered substrates but, since it seems the OP may be trying to make a decision on what to buy, he/she may want to consider inert substrates. I've never fully grasped the benefit of active substrates, since the water column provides such a simple way to always maintain more or less good consistency of alkalinity, general hardness and ferts. In particular, the many postings regarding findings that ferts dosed in the water column can easily match efficacy of ferts in the substrate. Until a recent teardown (due to misleading marketing regarding a supposedly inert substrate), I had the same inert substrate in place for ten years without issue and would have continued if it hadn't been for that problem. An active substrate will eventually require a tear down (if you want to keep employing one) and it seems parameters will drift as the active substrate begins to fail. 

This isn't meant as an attack, but I'd be interested to hear what value the users see in active substrates as compared to inert substrates.


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## dukydaf (Dec 27, 2004)

For me its the backup factor mainly, if something is not added in the water column enough, plants find it in the substrate. Go on vacation, plants can find whatever extra they need in the substrate. Longevity is not really a factor when the aquascape gets redone faster than 6 months or so. Some might prefer it because it allows for lean water column dosing or close-to hands off approach in low light setups. Some want the buffering capacity for fauna which prefers higher or lower pH than what the water available allows.


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## Zoidburg (Mar 8, 2016)

Deanna said:


> I realize that this is heresy to those that stand by high CEC and/or buffered substrates but, since it seems the OP may be trying to make a decision on what to buy, he/she may want to consider inert substrates. I've never fully grasped the benefit of active substrates, since the water column provides such a simple way to always maintain more or less good consistency of alkalinity, general hardness and ferts. In particular, the many postings regarding findings that ferts dosed in the water column can easily match efficacy of ferts in the substrate. Until a recent teardown (due to misleading marketing regarding a supposedly inert substrate), I had the same inert substrate in place for ten years without issue and would have continued if it hadn't been for that problem. An active substrate will eventually require a tear down (if you want to keep employing one) and it seems parameters will drift as the active substrate begins to fail.
> 
> This isn't meant as an attack, but I'd be interested to hear what value the users see in active substrates as compared to inert substrates.


Active substrates that are meant to buffer the pH down into the acidic range makes it easier to keep fish or shrimp that do best in those parameters. Many of the fancy Caridina shrimp require low pH and soft water. Having them in water that's harder and/or higher pH could mean the difference between having shrimp and having a thriving colony. Most shrimp species are "short lived", often living for 1-2 years, so most people generally want a colony that can more or less sustain itself, if not turn a profit.

The easiest and most stable way to maintain acidic pH is to first understand how KH and pH interact, as well as using these active substrates. It's not recommended to use products that alter the pH like pH Up and pH Down, leaves and alder cones may not lower the pH down far enough to make it acidic, and even if it does, then it often results in tea colored water... or there's the option of using CO2 which is either expensive or time consuming to get it right and maintain it. Shrimp are sensitive to CO2 and some may not even breed in a tank that has injected CO2. 



So with a tank that has good active/buffering substrates, you set the tank up with RO water and GH minerals, and in 1-5 years you replace it. If it's set up right, the shrimp you sell off from the tank would more than make up for the cost of replacing the substrate when it wears out.


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## Deanna (Feb 15, 2017)

Short-term insurance and shrimp breeding. Good points: both. Thanks.


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## Luciferene (Feb 7, 2018)

dukydaf said:


> CEC needs many partial negative charges on the substrate surface. Sometimes, molecules do not have very firm grasps on H+ atoms, especially when they are in large constructs where other partial forces are able to compensate for the loss of a + charge. A loss of a positive charge however charges the substrate with a negative one, creating its ability to attract (small)cations like Fe++, ... . On the other hand, more H+ in solution means lower pH. Could this be the link between CEC and acid buffering or more like chemistry pipe dream ? Just to clarify it does not have to be H+ alone, larger acids may act similarly.
> You make me curious but I already have enough testing projects for this summer :crying:


If I'm understanding your hypothesis correctly, you are thinking high CEC substrate loses hold on H+, lowering pH, and the resulting negative charge attracts other cations until equilibrium is reached. It's an interesting thought that may explain partially why active substrate tends to have high CEC and buffers.

To entertain the discussion, my question would be, that would be mean there would be constant absorption of cations while the buffering capacity exists. However if I'm understanding correctly, cation absorption period for high CEC is lot shorter than buffering capacity of active substrate. Also, active substrate then would have to affect pH and GH, but GH is not affected by active substrates from anecdotes of others. Since GH is measure of divalent metal ions, including Fe2+.



dukydaf said:


> You make me curious but I already have enough testing projects for this summer :crying:


I may be testing this out in small scale.  I'm thinking surface area to volume has something to do with buffering.  @dukydaf What are you going to be testing, if you don't mind sharing?
@Deanna I've had my short-termed success with inert substrates and column dosing so far, so for plants I'm not exactly sure about it's benefits yet. I'm thinking for dry start method, active substrates with high nutrient would be essential and possibly for plants that draws nutrients from solely roots. But what @Zoidburg said is spot on for why I'm using active substrate.


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## Zoidburg (Mar 8, 2016)

I don't recall which substrates remove KH and GH off hand, but Controsoil is one. With GH, it will absorb "x-amount" until it no longer absorbs any. Some people will "charge" the substrate during the cycling period and once it's done absorbing what it needs, will then use the water they desire within the tank.


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## madcrafted (Dec 23, 2017)

Fluval Stratum lowers GH temporarily too. I've also noticed that montmorillonite and peat moss will do the same. Pretty much anything with a high CEC. I would guess that most buffering substrates have a high CEC rating for this reason. I have yet to try ADA or SL-Aqua but I wouldn't be surprised if they dropped GH at least 20 ppm at first.


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## Deanna (Feb 15, 2017)

Luciferene said:


> @Deanna I've had my short-termed success with inert substrates and column dosing so far, so for plants I'm not exactly sure about it's benefits yet. I'm thinking for dry start method, active substrates with high nutrient would be essential and possibly for plants that draws nutrients from solely roots.


We often assume that all plants on Earth take nutrients through roots, but it doesn't necessarily work that way for our aquarium plants. They take very little from roots and can take all from the water column. Take a look at these two studies that show this:

http://www.plantedtank.net/forums/8-general-planted-tank-discussion/5657-root-feeders-water-column.html

http://www.plantedtank.net/forums/33-plants/876457-so-called-heavy-root-feeders-fact-fiction.html

So, the active substrates are good for the insurance aspect and shrimp breeding, but they do nothing for plants that can't be done with the water column.


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## madcrafted (Dec 23, 2017)

Deanna said:


> We often assume that all plants on Earth take nutrients through roots, but it doesn't necessarily work that way for our aquarium plants. They take very little from roots and can take all from the water column. Take a look at these two studies that show this:
> 
> http://www.plantedtank.net/forums/8-general-planted-tank-discussion/5657-root-feeders-water-column.html
> 
> ...


Good point. I would say the only time you would see a benefit from certain active substrates as far as plant growth is in a shrimp only tanks, where plants weren't a high priority and water column wasn't being dosed with sufficient levels of macros... if any at all. Many of the shrimp specific ferts have very low levels of these nutrients as well, much like Seachem's Flourish. The effects would be temporary, of course.


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## Seattle_Aquarist (Jun 15, 2008)

Deanna said:


> We often assume that all plants on Earth take nutrients through roots, but it doesn't necessarily work that way for our aquarium plants. They take very little from roots and can take all from the water column. Take a look at these two studies that show this:
> 
> http://www.plantedtank.net/forums/8-general-planted-tank-discussion/5657-root-feeders-water-column.html
> 
> ...


Hi Deanna,

I have trouble reaching the same conclusion you have based upon what I have read. 

I agree with the statement that in nature the amount of nutrients in the water column is minimal. This is based upon what I have learned from reading Christel Kasselmann's book and listening to her presentation. In nature bodies of water (rivers, lakes, etc.) have minimal nutrients and the substrate is the primary source of nutrients for the plants.

This is re-enforced by what we know about the biology of plants. Most of the plant species in our tank are 'marginal' species, meaning that they live along the edges or rivers, streams, and lakes and live part of the year submerged and part of the year emersed. When a plant is emersed there is no water column so the only source of nutrients (and moisture) for the plant is the dirt (substrate). Also, when a plant is emersed the leaf structure of the leaves change, the cuticle layer of the leaf becomes thicker to help reduce water loss of the plant through plant respiration. Unfortunately the thick cuticle layer also reduces the ability of the plant to uptake nutrients (including CO2) through the leaves, this is partly why a plant that is grown emersed grown may lose its leaves when the plant is submerged.


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## Deanna (Feb 15, 2017)

Seattle_Aquarist said:


> Hi Deanna,
> 
> I have trouble reaching the same conclusion you have based upon what I have read.
> 
> ...


Yes, Roy, I see your logic, so I'm going to take a stab at each item from my perspective.

- In the first link I provided, there is a quote from Tom Barr which, almost to the letter, matches your comments about how plants work in nature. He goes on to say that, while our plants need to adapt to the changes in nature (as you said) they also adapt to being fully immersed and, in that case, can absorb all nutrients via their leaves.

- I have read theories that the roots in our "marginal" plants, because many of them are in a stream, are primarily used for anchoring the plants. Of course, they also are able to draw nutrients from the soil. Some of these plants, when placed in our aquariums, want their roots above the substrate so that they can draw from the water column rather than the substrate.

- The implied inverse of your comment about plants changing when emersed is that they are able to capitalize on an immersed state. I have the same understanding about them structurally changing, immersed vs. emersed, as you do. They can go back and forth with ease.

So, in a sense, we are both right ...due to the adaptability of the plants (very well-designed life forms). My only point was that, while the plants will derive nutrients from an active substrate, if provided, they don't need an active substrate if all the nutrients are supplied in the water column. They will do just as well drawing nutrients from above the substrate.


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## jeffkrol (Jun 5, 2013)

alternate ad hoc method:
Adding a very small layer of "coral sand" b4 topping w/ high CEC substrate.. 

Crude but fairly effective..

It's more insurance than technical..


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## Seattle_Aquarist (Jun 15, 2008)

Deanna said:


> Yes, Roy, I see your logic, so I'm going to take a stab at each item from my perspective.
> 
> - In the first link I provided, there is a quote from Tom Barr which, almost to the letter, matches your comments about how plants work in nature. He goes on to say that, while our plants need to adapt to the changes in nature (as you said) they also adapt to being fully immersed and, in that case, can absorb all nutrients via their leaves.
> 
> ...


Hi Deanna,

Another way to look at is as plants are opportunistic. In other words if it is easier for a plant to get a particular nutrient from the substrate it will get there and if it is easier for a plant to get a nutrient from the water column it will get it there.


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