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Discussion Starter · #1 ·
Is it possible that capping a dirt substrate will keep it from absorbing ferts from the water column?

If clay or kitty litter without a cap is used, does it absorb more ferts? If so, wouldn't it be possible to fertilize larger doses less frequently?

Like in tank 'charging' of your substrate.
 

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I don't think so. Why do you want to keep ferts out of the water column?

I've never used kitty litter, but the few posts I've read about around here has stated that it turns into a mushy mess. As always, I advocate for your experimenting, but I'm not sure that is the way to go.
 

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Discussion Starter · #3 ·
I don't think so. Why do you want to keep ferts out of the water column?

I've never used kitty litter, but the few posts I've read about around here has stated that it turns into a mushy mess. As always, I advocate for your experimenting, but I'm not sure that is the way to go.
It's more about charging a substrate, and how long you can go without ferts because of that substrate. Say I want to fertilize once every three months, could it work if I dose more of everything, but it get's taken up by the substrate and is available for the three months. LIke reverse root tabs. Water Column Tabs once every 3 mo.
 

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Is it possible that capping a dirt substrate will keep it from absorbing ferts from the water column?

If clay or kitty litter without a cap is used, does it absorb more ferts? If so, wouldn't it be possible to fertilize larger doses less frequently?

Like in tank 'charging' of your substrate.
Well I dont believe the substrate absorbs ferts from the water column to begin with. Thats why you need things like root tabs if using an inert substrate. Capping a substrate is really for aesthetic and maintenance reasons. If you dont cap a dirt substrate then the dirt can get kicked up too easily and cloud the tank. The idea of something like dirt as a substrate is that it is nutrient rich to begin with; not that it will absorb ferts from the water column.
 

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It's more about charging a substrate, and how long you can go without ferts because of that substrate. Say I want to fertilize once every three months, could it work if I dose more of everything, but it get's taken up by the substrate and is available for the three months. LIke reverse root tabs. Water Column Tabs once every 3 mo.
Here's the thing. If oxygen doesn't get into the substrate for plant roots, the roots of the plant will rot which means the plant will die. I don't believe in the theory that whatever it put into the substrate stays in the substrate because eventually what is under there is going to make it's way into the water column one way or another.

If you really don't want to deal with liquid ferts, then using root tabs is the way to go. Whether you buy them or make them from gel caps and Osmocote, the plants will be fed. Dave from ADU on You Tube uses the Osmocote method and his tanks are drop dead gorgeous. I don't think he's capable of putting together a bad tank. His methods of how he deals with problems has changed over time, but lately he has been a holistic approach and it's pretty cool if I do say so myself.

The thing to keep in mind is, what are you feeding. You've mentioned several times that you're having algae issues. If we had tank details, certainly there are enough smart people around here that are willing to help and get you through it. If you overfeed a lightly planted tank with slow growing plants, too much food at them will have a bad outcome. Just as not feeding a high tech not enough has a bad outcome.
 

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If say possibly of you have super deep substrate, but I'd be willing to bet diffusion means it wouldn't matter in most situations... only thing I can imagine it changing is capacity of the substrate to store nutrients (more inert substrate would mean less capacity) and it might take a little bit longer to adapt and release with a cap... but that would be merely speculation
 

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Discussion Starter · #7 ·
Here's the thing. If oxygen doesn't get into the substrate for plant roots, the roots of the plant will rot which means the plant will die. I don't believe in the theory that whatever it put into the substrate stays in the substrate because eventually what is under there is going to make it's way into the water column one way or another.

If you really don't want to deal with liquid ferts, then using root tabs is the way to go. Whether you buy them or make them from gel caps and Osmocote, the plants will be fed. Dave from ADU on You Tube uses the Osmocote method and his tanks are drop dead gorgeous. I don't think he's capable of putting together a bad tank. His methods of how he deals with problems has changed over time, but lately he has been a holistic approach and it's pretty cool if I do say so myself.
I'll check out Dave. But recently someone mentioned only fertilizing a few times a year, and having great results. I'm just wondering how they can do that, since they didn't mention type of substrate or whether they use root tabs. Reverse engineering on a claim posted by member 'Niko', of course.
 

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There is mention of Tom's experiment in this thread http://www.plantedtank.net/forums/29-substrate/127768-can-high-cec-substrates-recharged.html

If you don't want to read it, here is the quote from Tom:

It required a lot more $$$ and time for me personally

Basically, the ADA AS or any clay loam ought to be relatively close, will decline in Nitrogen over time.

The other ferts will still be there.
I suppose if you did not dose anything to the water, then they will be drained also at a higher rate, but they should last 5-10 years or so for most things except N and dosign K+ and traces will certainly help, as well as PO4.
If Tom is complaining about time and money, then I personally wouldn't bother with it, but if you're up to that, then go for it.

I watched a video on Green Machine the other day where they talked about the life span of ADA soils. They said 3 years, but under what circumstances? Did they test it with all kinds of water or just whatever they use? I doubt it.

Like the great "No ferts..." thread, if people are getting this great results but fail to show how it is done, I think that says something, but that's just me.
 

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Is it possible that capping a dirt substrate will keep it from absorbing ferts from the water column?

If clay or kitty litter without a cap is used, does it absorb more ferts? If so, wouldn't it be possible to fertilize larger doses less frequently?

Like in tank 'charging' of your substrate.
Usually, people worry about nutrient rich substrates leaching into the water column, so your question made me think if what comes out of can get back into the soil. The short answer is no. I'll try to brake it down into some short ideas.

Given a normal setup that tries to avoid anaerobic areas (ie- the top layer is not to thick or too dense) there will always be some water permeating to bottom layer.

Will it take up more nutrients (if the high CEC substrate is on top) ?

The location will not change the proprieties of the soil so gram per gram – no. However the interaction will happen at a faster rate if the soil is in contact with a good water flow. This increased exchange rate goes both ways, both at caching and releasing.

What nutrients will be taken up by the substrate?
Now here is the real question. This will also answer your question if it possible to fertilize in large doses based on the belief that the substrate will take up the nutrients.
When we talk about the soil releasing and taking up nutrients we are referencing the soil CEC (cation exchange capacity) and AEC( anion exchange capacity). The AEC soil capacity is mostly covered by hydroxyls but under acid soil pH it can be a source of H2PO4-
Thus the main interaction relates to CEC, exchanging Ca(2+) Na+ K+ for H+ (mostly). This is all fine for cations (have a positive charge). However our fertilizer also have NO3- , PO4(3-) which will not interact with CEC but will remain in the water column until consumed.

What about dirt ?
In the case of topsoil or aquarium substrates fertilized with fish poop they are rich in N from an organic source. This organics slowly decompose and release NH4+ in enough supplies for a low plant mass/growth.
In a natural ecosystem there are often spikes in nutrients at one point and then reuse and storage of them for later use ( think autumn). Our aquariums are NOT A NATURAL ecosystem, they are too small, too separated from outside input/output and to aesthetically oriented.

Fertilizing once a lifetime

I have to say I am less impressed by that someone’s description of the method and claims made… that being said… You can certainly run your aquarium with no special fertilizers added, just fishfood and the minimal water changes, Diana Walstad described this method in her book and long before that people were growing plants like that. You are certainly limited in terms of plant selection and rate of growth.
I had first hand experience with a peat/sand aquarium with no fertilization except fish food from day one…. It only had Vallisneria and some other water weeds. Another example is of a 62.5 gallon tank with sand and JBL Aquabasis ( branded clay). Run for 2 years as a high maintenance tank, winded down to less light, no ferts added, almost no water changes .By that time the substrate had a good mix of fish and plant waste matter mixed into it. The aquarium went on like this for 5 years until I sold it. Sure lost the demanding plant types but it was a green jungle in there that needed trimming about 2-3 times a year. With the amount of work that went into maintain that aquarium, very pleased with the results.

Adding extra ferts from time to time might help to cover the limiting nutrient and place it back on CO2 or light limitation. However not all of these nutrients will be taken up by the substrate and could result in algae blooms.
 

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I've keep glass bottom tanks for the past couple of years. I have better growth/health in the tank when I have coir mat as a substrate. So without anything other than the experience, I'd say coir is interesting in that it is pH neutral, and is very high CEC. I think that it may somehow equalize the distribution of ferts by absorbing (attracting) them, and then releasing them as needed. ? I have bad experiences with typical substrates, so I continue to look for alternatives. I found the coir, and so far it has it's good and bad points. Depends on your setup.

Sorry, and thanks, I forgot to add the link in my mention.

But the money issue does not make sense to me. I would think that if you find a high CEC substance that works as a substrate, it may cost you less money. I am working with coir, and it is extremely inexpensive.
 
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