# Substrate CEC lab analysis (Lab work on hold, now full discussion)



## Quagulator (May 4, 2015)

I think we have all seen topics of various substrates, and more often than not CEC is usually brought up. Plenty of opinions out there, so I was wondering if there is enough interest among other hobbyist to justify a lab analysis of various substrates. There may be data out there that I don't know about which is why I'm asking you guys. I have access to a credible soil analysis lab through my work, and I'm sure I can get them on board testing aquarium soil/substrate instead of agricultural soil, but before I jump into it, I was hoping to see what kind of demand there was from aquaria hobbyists before I start investing time and likely money into this... 

Of course I will do this in a scientific matter, and a simple CEC test will come with various other test results as well. The testing would be followed up with a brief article describing CEC in detail, and the results of each substrate. 

I'm thinking of doing the most common types of substrate we are seeing:

Aquasoil
Stratum
Eco-complete
Flourite
Blasting sand 
Pool filter sand (probably the same as BDBS, interesting to see if their is a difference)
Mineralized potting soil
etc etc.

Now of course this would only be made possible if I can justify cost and availability of substrate and so on, but I figured I should start stirring up the pot a little.... 

Let me know your thoughts, good/bad idea? Love to see what others have to say about a test like this.

Cheers,

Q


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## Seattle_Aquarist (Jun 15, 2008)

Hi @Quagulator,

I think it would be a good idea. The last time this was done was about 2000 with the results of the testing published on pages 17-23 of *Planted Aquaria Magazine Summer 2000 issue* (hi-res .pdf - takes a while to load) the predecessor of the *Aquatic Gardeners Association* current magazine _The Aquatic Gardener_. The testing method and instruments involved are on page 22. Jamie Johnson was the author of the article. Here is a summary of the results, only a few of the substrates listed are ones we typically discuss today. FYI, the Turface listed as #16 and #16a in the chart are calcined Montmorillonite clay material very similar to the Safe-T-Sorb that we use today.


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## madcrafted (Dec 23, 2017)

Thanks for posting that. I knew montmorillonite clay was high in CEC. Many folks use this in their organic garden soils as well as bentonite. Clays in general have a high CEC. Worm castings, too, have a decent CEC. 

I'm guessing Eco-complete falls right around the 6 mark too, making it fairly low compared to many other sources. Surprised to see Flourite so low as well. I guess these soils are good for giving something for roots to grab ahold as well as offering homes to beneficial bacteria more so than storing nutrients?


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## Quagulator (May 4, 2015)

Wow, so considering eco-comp and fluorite both have low rated CEC's I think I've gotten scammed 

Maybe it isn't worth testing as the only aquarium substrate worth noting would be aquasoil type substrates (high or low CEC iI'm not sure) and "dirt" based substrates. 

People are always talking about burning out dirted tanks, but organic soils have some of the highest rated CEC's out of all soils, so essentially they should be able to store nutrients fairly well if you pick up a dosing regime.... But then why dirt it if you have to supplement over time anyway? May as well just use an attractive sand and dose straight away..... 

The only other large thing I can see is the larger surface area/porous space on flourite/eco-comp should allow lots of microbial activity which in turn will contribute to nutrient cycling. To be fair to Seachem and Caribsea, they don't claim a high CEC on their websites.... 

Did us hobbyists pick up the CEC term when reading about higher pour space? Because if the results Seatle posted are correct, our "planted" tank substrates aren't what we thing. Regardless, if the particle or pour is not negatively charged, it has no CEC anyway... Maybe I'll have to to a meta-analysis on the matter and swing back a later date with some results.


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## Seattle_Aquarist (Jun 15, 2008)

Hi @Quagulator,

I believe that ADA Amazonia has a CEC in the mid-20's; it is believed to be composed of rice patty soil.


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## Quagulator (May 4, 2015)

Seattle_Aquarist said:


> Hi @Quagulator,
> 
> I believe that ADA Amazonia has a CEC in the mid-20's; it is believed to be composed of rice patty soil.


Do you have a credible source for that? I'm really interested in getting a list with references together now instead of collecting and measuring samples, if the leg work has been done by reliable sources, I am willing to put the info together. I actually have some organic potting soil screened and mineralizing as we speak, I can certainly get that tested. It would be interesting to test now and then 1 year of use and compare.


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## Seattle_Aquarist (Jun 15, 2008)

Hi @Quagulator,

Sorry, I believe I read it in The Barr Report but that was several years ago. I don't think any actual testing was preformed. https://barrreport.com/threads/anyone-know-the-cec-value-of-aquasoil.11733/


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## jeffkrol (Jun 5, 2013)

It's mostly just dirt.. 









NATURE AQUARIUM NOTES#12 Features of Amazonia Light | ADA - AQUA JOURNAL


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## Surf (Jun 13, 2017)

I would be interested in seeing the black diamond blasting sand analysis since I am considering putting that in my tank. Also what is the current market cost for performing these tests?

Bump: I would be interested in seeing the black diamond blasting sand analysis since I am considering putting that in my tank. Also what is the current market cost for performing these tests?


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## Seattle_Aquarist (Jun 15, 2008)

Hi @Surf,

Black Diamond Blasting Sand (BDBS) is totally inert, it is 99%+ coal slag. https://www.menards.com/msds/101672_002.pdf


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## Quagulator (May 4, 2015)

Surf said:


> I would be interested in seeing the black diamond blasting sand analysis since I am considering putting that in my tank. Also what is the current market cost for performing these tests?
> 
> Bump: I would be interested in seeing the black diamond blasting sand analysis since I am considering putting that in my tank. Also what is the current market cost for performing these tests?




Blasting sand would be <1 meq/100g so a very very poor rating. Organic matter and true clay particles would bring CEC up the most. While sand and silt particles would bring the CEC rating down. 

The issue when applying a high/medium/low rating of CEC to aquarium substrates is that the true surface area is a fraction of what a traditional soil would be. 

For example with the same volume of a traditional clay soil vs aquarium substrate, the clay soil would have immensely more true surface area, more organic matter and therefore a much, much higher CEC. Even true sandy soils have a CEC of ~3 meq/100g where as in the above chart play sand got a 0.1 ...

Now that I’ve seen some data, I honestly think CEC in aquaria should be disregarded... sands/fluorites/ecocompletes have very low ratings, aquasoil should have a decent rating, but unless we are using true sand/silt/clay soils (some are, ex: digging up some dirt from your back yard for aquarium use), or organic soils, then CEC in the planted tank is insignificant. 

But, we still have the issue many talk about.... running your dirted tank out of juice. Organic matter contributes the greatest to CEC, so if we fertilize can we take advantage of the CEC? Maybe... but without taking samples we can’t be sure. Maybe organic potting soil is just that, 100% organic matter that will decompose not into a soil, but into organic compounds lost to leaching/uptake by plants and microbes, makes me wonder if grabbing a shovel and putting my work boots on is a better route to a great planted tank substrate than most of us take. 

Of course this is all hypothetical, we have all seen great tanks regardless of the substrate used. Overthinking at its best  


Oh! Almost forgot, I can’t tell you my company’s pricing for competitive purposes, but a $10 bill won’t buy you a sample, a $20 bill will  


Sent from my iPhone using Tapatalk


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## klibs (May 1, 2014)

BRING ON THE SCIENCE

I AM PREPARED

Sent from my SM-G930T using Tapatalk


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## Quagulator (May 4, 2015)

Oh and btw, when I say organic soils I DO NOT mean a soil where there is no use of pesticides, GMO’s and is registered under whatever organic foods organization of your liking. What I’m referring to is TRUE organic matter, more specifically carbon based molecules. So an “organic soil” is a soil containing more than 20% carbon based physical matter by weight. 

While we are being all scientific and all... I figured I should clarify. 


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## SingAlongWithTsing (Jun 11, 2015)

any chance you can test pumice too? specifically from here General Pumice Products

supposedly pumice has high cec 75 meq/ml

Soils 2: Mineral ingredients


> With a cec that hovers around 75 meq/100g (depending on source) it requires less frequent fertilizing that most other soil components when used alone. Pumice can hold large quantities of water - up to four times its own weight. This, coupled with the soft and easily powdered surface means that when used alone or with other absorbent materials, careful watering is necessary to avoid water logging.


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## jeffkrol (Jun 5, 2013)

You might find this interesting.. 

https://link.springer.com/article/10.1007/BF00751278



> Organic matter levels were rather low (range 0.37 to 6.42 %),
> but the values were higher than organic matter contents of most
> Alabama agricultural soils (MILLAR, 1955). Since the lakes had received fertilization
> and were very productive, higher organic matter levels were expected.
> ...


Not going to buy it so only a snippet.. 
Personally I lean to pore size, compaction, and breakdown to be more important. by guess.. nothing really concrete..
Root penetration and hold down ability and not breaking down to mush..as well as gas/water exchange.


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## roadmaster (Nov 5, 2009)

Have experimented with all manner of soils and DIY mixes of same.
Best result's were with soils mixed with cat litter and or Safe-T-Sorb with sprinkling of Osmocote.
One such tank has been running for a couple year's with soil mixed with Azomite,Jersey Green sand,and capped with the product safe-T-Sorb.
Not enough fish load,fish poo,fishfood's,to dissolve and further nourish the substrate /root areas ,so I add dry nutrient's once a week or two also.
I gauge the performance by observing a couple large Sword plant's that throw out/up long stalk's, that droop over the outside of the tank, and sometimes produce tiny white flower.
With larger fish loads, and subsequent consistent organic input from the biological break down of food's/waste, larger plant mass can be sustained for longer period.
With soil alone capped with inert substance, no water column dosing ,the plant mass can use up nutrient's from the soil and begin to struggle .
How long does this take??(too many variables).
I prefer to hedge my bet with providing a nutritious substrate mix, and also nutrient's via the water column.
Cat litter,Safe-t-sorb, soil, helps me provide a nutrient sink.
Assumes you can lay to rest in your mind, that nutrient's in excess = algae.
I Dose what those who use EI method dose in a day once a week, or twice a week, depending on plant mass.
From my own observations,,not many folks leave tanks set up long enough to take advantage of CEC capability before they tear it down to try something else.
My two cent's.


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## Quagulator (May 4, 2015)

jeffkrol said:


> You might find this interesting..
> 
> https://link.springer.com/article/10.1007/BF00751278
> 
> ...


"even Alabama Agricultural Experiment Station which had received high rates of fertilization or supplemental feeding for 15 to 20 years contained only 2 to 6 % organic matter. "

Too many variables in organic matter build up: biggest being tillage, residue management, soil texture, moisture, C:N ratio of organic matter etc etc... with a C:N > ~10:1 you will have immobilization ; <10:1 mineralization (of nitrogen that is, but its a yard stick of determining decomposition and organic matter build up). So, regardless of how much fertilizer is placed down, if there is extensive tillage, removal or incorporation of organic residues, proper soil moisture + temperature and a soil texture allowing for good aeartion, organic matter levels will decrease despite high fertilizer rates. Decomposition is happening faster than additions of organic matter. 

Thanks for that study, the results in figure 1 go along with what I was saying... As organic matter in the soil increases, so does CEC, basically in a linear fashion.

Bump:


roadmaster said:


> Have experimented with all manner of soils and DIY mixes of same.
> Best result's were with soils mixed with cat litter and or Safe-T-Sorb with sprinkling of Osmocote.
> One such tank has been running for a couple year's with soil mixed with Azomite,Jersey Green sand,and capped with the product safe-T-Sorb.
> Not enough fish load,fish poo,fishfood's,to dissolve and further nourish the substrate /root areas ,so I add dry nutrient's once a week or two also.
> ...



The more I think about it, the more it makes sense. The "dirt" is a big source of organic matter, the clay amendments are a key building block of the texture of the substrate. So given a proper ratio, we can expect the organic matter decomposition to feed the plants AND feed the clay CEC. This is of cource dependent on the surface area and pore space of the clay. In doing so we can help create a soil structure that is not black muck, and take advantage of the CEC if given the chance.... 

Remember, CEC is based on exchangeable CATIONS, mainly calcium (Ca2+), magnesium (Mg2+), sodium (Na+) and potassium (K+) .... also Hydrogen and aluminum cations.... but we aren't too interested in those two.


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## madcrafted (Dec 23, 2017)

I'm not so sure that CEC ratings are even that important for aquatic plants. I mean, most of us dose fertilizers to the water column or use root tabs. Most aquatic plants aren't particular about where they get there nutrients from. There's always an abundant amount of nutrients when using methods like EI. I think it's far more important in organic soil where nutrients have a tendency to be leached away with watering, especially with heavily aerated soils.


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## roadmaster (Nov 5, 2009)

Most all soils by definition,, are comprised of decayed, or decaying organic material along with some minerals and or clay,sand,rock,depending on geographical locations.


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## Quagulator (May 4, 2015)

madcrafted said:


> I'm not so sure that CEC ratings are even that important for aquatic plants. I mean, most of us dose fertilizers to the water column or use root tabs. Most aquatic plants aren't particular about where they get there nutrients from. There's always an abundant amount of nutrients when using methods like EI. I think it's far more important in organic soil where nutrients have a tendency to be leached away with watering, especially with heavily aerated soils.


While dosing certainly can solely supply our plants with their needs, the substrate CEC can be seen as a reserve for when we are either missing doses or when we aren't dosing enough / dosing at all, so EI is obviously out of the question, unless we are using EI purposely for "recharging" the substrate. But I agree, the CEC rating for most "planted tank" substrates is poorer than a traditional sandy soil.... So really the "reserves" are likely NOT bound in the CEC, but rather bound to the decomposition of organics (fish waste, plant matter, foods etc.). 

It should be noted that while organic matter found in the substrate is just that.... organic material found mixed in the substrate, not bound into the CEC, (well, of course some is bound in the CEC) and over time microbes will decompose the organic material into plant available forms, which further points me to believing nutrient reserves found in our tanks are likely not significantly related to the substrate CEC, but rather to the decomposition rates of various organic compounds we have sitting on/in the substrate or suspended in the water column.


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## Seattle_Aquarist (Jun 15, 2008)

madcrafted said:


> I'm not so sure that CEC ratings are even that important for aquatic plants. I mean, most of us dose fertilizers to the water column or use root tabs. Most aquatic plants aren't particular about where they get there nutrients from. There's always an abundant amount of nutrients when using methods like EI. I think it's far more important in organic soil where nutrients have a tendency to be leached away with watering, especially with heavily aerated soils.


Hi @madcrafted,

I would agree with you in that 'true aquatics' (plants that naturally occur only in water) can likely get all the nutrients they require through the water column. However well over 50% of the plants we use in our aquarium are 'marginals' that live part of the year completely submerged and part of the year either partially or completely emerged from the water. Obviously those species cannot absorb nutrients from the water column when emerged and must rely on their roots to supply the nutrients required for growth. Also 'marginals' typically have a thicker cuticle layer on their leaves making it more difficult to absorb nutrients from the water column even when submerged. I believe 'marginals' to be opportunistic and will get nutrients wherever they can probably from both roots and substrates when submerged. Since I have both 'true aquatics' and 'marginals' in my tank I provide nutrients both in the substrate and the water column.


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## Quagulator (May 4, 2015)

roadmaster said:


> Most all soils by definition,, are comprised of decayed, or decaying organic material along with some minerals and or clay,sand,rock,depending on geographical locations.


Yes, and the proportion of sand/silt/clay/organic matter will determine many factors leading to the classification of the soil. Usually this is determined by a soils parent material, found at the bottom of a soil profile, where as the parent material is withered away creating the main ingredients to a soil. 


Does anyone have a concrete source that shows what exactly makes up aqua soil? I was reading some dark corners of the internet and it seems they take a specific soil or combinations of soil and formulate a granular product, mainly humic based.... so theoretically it should have a decent CEC (which has been pointed out in this thread) yet also it has nutrients plant available from the get go.... and organics that are decomposed to be plant available at a later date. When looking at that, we are pretty much doing a "poor mans" aquasoil with our mineralized dirt with or without clay additives etc.... The more you know....


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## jeffkrol (Jun 5, 2013)

Particle size (texture) chart.. Doesn't include organics...or pebbles.. 
Determined by mass (weight)

complicated by fired clay products though since it isn't "particle-ized"... 



> Grain size is classified as clay if the particle diameter is <0.002 mm, as silt if it is between 0.002 mm and 0.06 mm, or as sand if it is between 0.06 mm and 2 mm. Soil texture refers to the relative proportions of sand, silt, and clay particle sizes, irrespective of chemical or mineralogical composition.





> Loamy soils with high organic matter are very well suited for high demand crops such as vegetables and fruit.


still. wouldn't really personally consider substrates w/ higher than 10-20% organics.. like organic compost..
Or peat if you want acidity..

Seems this is more a consumable than not...




> silt is chemically distinct from clay, and unlike clay, grains of silt are approximately the same size in all dimensions; furthermore, their size ranges overlap. Clays are formed from thin plate-shaped particles held together by electrostatic forces, so present a cohesion.


If you wanted to do a mix from scratch, not sure where one buys silt..
mushing cat litter is easy enough..

Then again. BNW..
https://www.etsy.com/listing/280738...MI3a-JqueW2QIVkrfsCh3JewXCEAkYASABEgLPFvD_BwE

http://www.glenns-garden.com/sand-silt-clay-what-do-you-got/


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## aquazone (Jul 9, 2003)

That article above was my data. I did it for members on the Aquatic Plants Digest and it grew until we had enough data to publish.


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## Quagulator (May 4, 2015)

jeffkrol said:


> Particle size (texture) chart.. Doesn't include organics...or pebbles..
> Determined by mass (weight)
> 
> complicated by fired clay products though since it isn't "particle-ized"...
> ...



And that's a point I should have touched on more. 

Looking at almost all retail planted substrate, they are a granular product, so right from square one, that inhibits enough true "particles" ex: sand/silt/clay which was shown, lets us fluorite for example, with a poor rated CEC. Clay has more surface area than sand, mostly do to the particle size and shape/orientation resulting in generally a higher CEC (exuding particle charges in this assumption) where as a granular product has much much larger particles sizes, limiting the amount of surface area and porous space that can contribute to an increased CEC. 

Then again.... Perhaps the particle charge and type of clay has a greater impact on CEC than comparing different textures...


"" Clay has a great capacity to attract and hold cations because of its chemical structure. However, the different clay types occurring in Tasmanian soil have different CECs (table 1). It is highest in montmorillonite clay, found in black soils. It is lowest in heavily weathered kaolinite clay, found in Ferrosols and slightly higher in the less weathered illite clay. Humus, the end product of decomposed organic matter, has the highest CEC value because organic matter colloids have a large surface area and large quantities of negative charges. Humus has a CEC two to five times greater than montmorillonite clay and up to 30 times greater than kaolinite clay, so is very important in improving soil fertility. A higher CEC usually indicates more clay and organic matter is present in the soil and so high CEC soils generally have greater water holding capacity than low CEC soils. ""

Bump:


aquazone said:


> That article above was my data. I did it for members on the Aquatic Plants Digest and it grew until we had enough data to publish.


Which data was that again??


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## jeffkrol (Jun 5, 2013)

> Then again.... Perhaps the particle charge and type of clay has a greater impact on CEC than comparing different textures...


AFAICT.. yes..
But texture does affect gas exchange..
too deep and little pore space it goes anareobic..2 edged sword......




> A higher CEC usually indicates more clay and organic matter is present in the soil and so high CEC soils generally have greater water holding capacity than low CEC soils. ""


completely irrelevant in an aquatic environment. Minor importance in dry starts..


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## aquazone (Jul 9, 2003)

Seattle_Aquarist said:


>


This data. I performed all the testing for this article many moons ago. We had many of the same discussions on the Aquatic Plant Digest about minerals, Fe, CEC, and the like. The lab I was working in at the time afforded me the opportunity to do the testing. Dave published in his Aquatic Magazine. Many of the findings surprised us all, especially the low CEC of Flourite. We were amazed how well plants grew in it yet the CEC was so poor. We kind of decided maybe CEC didn't hold that much water when it came to aquatic nutrition. Sort of like sea oats growing in pure beach sand. Dr. Morin of Seachem even sent me enough Flourite, that to this day, I still have 5 gallon buckets of it I've never used.


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## Quagulator (May 4, 2015)

Well, I'll look into getting some mineralized potting mix tested, maybe make up a batch of pulverized clay and mix that into some dirt too and see if there's a difference... I doubt it really. If anyone has some soil from a dirted tank that is 1 year+ in a heavily planted scenario and wants to send my a sample I can get that looked at too. Usually need about 1 lb of soil for a decent sample.


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## madcrafted (Dec 23, 2017)

aquazone said:


> This data. I performed all the testing for this article many moons ago. We had many of the same discussions on the Aquatic Plant Digest about minerals, Fe, CEC, and the like. The lab I was working in at the time afforded me the opportunity to do the testing. Dave published in his Aquatic Magazine. Many of the findings surprised us all, especially the low CEC of Flourite. We were amazed how well plants grew in it yet the CEC was so poor. We kind of decided maybe CEC didn't hold that much water when it came to aquatic nutrition. Sort of like sea oats growing in pure beach sand. Dr. Morin of Seachem even sent me enough Flourite, that to this day, I still have 5 gallon buckets of it I've never used.


I feel the same way about the subject. While I'm still fairly green when it comes to aquatic plants in particular, I've seen many successful tanks that had swords and crypts growing just fine in coal slag as well as pool filter sand. It's hard for me to believe that CEC is of any real importance. I'm sure it doesn't hurt to have 'reserves' in the substrate, especially if you vacation often. In these cases, you could also lower light intesity and/or cut the photo period to reduce plants nutritional demand. Root tabs can also help in this regard.

I would probably just pick a substrate based on ease of planting and ability to give roots a nice structure to spread out in. It's not like they have tiny little root hairs that seek out soil particles in search of water/nutrients like terrestrial plants. We're dealing with larger water roots here that uptake water/nutrients at a much faster pace... not to mention foliar uptake.

Again, this is just my observation. Can be taken with a grain of epsom salt.


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## Seattle_Aquarist (Jun 15, 2008)

aquazone said:


> This data. I performed all the testing for this article many moons ago. We had many of the same discussions on the Aquatic Plant Digest about minerals, Fe, CEC, and the like. The lab I was working in at the time afforded me the opportunity to do the testing. Dave published in his Aquatic Magazine. Many of the findings surprised us all, especially the low CEC of Flourite. We were amazed how well plants grew in it yet the CEC was so poor. We kind of decided maybe CEC didn't hold that much water when it came to aquatic nutrition. Sort of like sea oats growing in pure beach sand. Dr. Morin of Seachem even sent me enough Flourite, that to this day, I still have 5 gallon buckets of it I've never used.


Hi @aquazone,

First of all thank you for testing and publishing this information 18 years ago, I have referred back to it several times over the years. I don't know if the sea oats analogy holds, many plants have learned evolve and adapt to various ecosystems on our planted, including the volcanic vents on the ocean floor. 

I guess one way to test would be to fill two pots with substrate, one with high CEC and the other with inert, put identical cuttings in each pot, and put them in the same tank side by side and see if there is a substantial difference in growth or not....hmmmm.


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## roadmaster (Nov 5, 2009)

Seattle_Aquarist said:


> Hi @aquazone,
> 
> First of all thank you for testing and publishing this information 18 years ago, I have referred back to it several times over the years. I don't know if the sea oats analogy holds, may plants have learned evolve and adapt to various ecosystems on our planted, including the volcanic vents on the ocean floor.
> 
> I guess one way to test would be to fill two pots with substrate, one with high CEC and the other with inert, put identical cuttings in each pot, and put them in the same tank side by side and see if there is a substantial difference in growth or not....hmmmm.


Yes,This ^
I have seen substantial difference from just such a comparison while growing Sword plant's in pot's in my Aquariums.(large fishes would root them up otherwise).
All sort's of mixes were tried in these pot's, and is what led me to try and replicate these mixes I used on much larger scale as substrate, now that cichlids were/are no longer being kept, that would otherwise root up the young plant's sometimes daily.
Once you see the difference for yourself, then that was all I needed.
Would not try to compare the nature and properties of soils in non aquatic environment's to that in aquatic enviornments .
Microbial ,chemical reaction's are seldom same/same.
Same for CO2/O2. production(See organic carbon from soils,and plant's abilities to produce O2 and transport same to root areas in aquatic enviornment's.)


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## Seattle_Aquarist (Jun 15, 2008)

Hi All,

Yes this is an old thread. @Quagulator asked if there was any documentation providing the CEC rating for ADA Aquasoil. I came across this today. It is for ADA Amazonia I but it does show a respectable CEC level of 24.7 to 27.4 CEC levels for Amazonia I. I'll keep looking for quantitative data for Amazonia II.......it may take a few more years! lol


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