# Is water column fetilization sufficient?



## Darkblade48 (Jan 4, 2008)

Water column fertilization will be sufficient for most plants; in the case that substrate fertilization is needed for heavy root feeders (Swords, _Cryptocoryne_ sp., etc.) then you could always use root tabs if you want to keep your current substrate.


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## sarahspins (Sep 24, 2012)

I had poor growth with my swords and crypts until I started using root ferts (I use osmocote+ in gel caps).. since then they've absolutely exploded with growth and one of my swords has made babies twice.


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## Makenga (Jun 30, 2013)

Thank you both for the prompt replies. Would adding a layer of laterite on the bottom gain me much in terms of happier plant roots in general?


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## plantbrain (Dec 15, 2003)

Darkblade48 said:


> Water column fertilization will be sufficient for most plants; in the case that substrate fertilization is needed for heavy root feeders (Swords, _Cryptocoryne_ sp., etc.) then you could always use root tabs if you want to keep your current substrate.


Can you name a plant I cannot grow without sediment ferts, eg, very very well?


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## plantbrain (Dec 15, 2003)

Makenga said:


> Thank you both for the prompt replies. Would adding a layer of laterite on the bottom gain me much in terms of happier plant roots in general?


No, a rich sediment can impart a backup if you forget to dose the water column.

People who are not consistent, or under dose the ferts will see, obviously.........an increase in growth for plants if they add more ferts(go figure), the location does not matter.

I've had massive swords, Crypts for 20+ years with simple sand and water column ferts. That said, I see no good reason to avoid using a rich sediment, or ferts in the sediment.

They will leach out over time and go into the water column, likewise, water column ferts also diffuse into the sediment in plain sands etc. There's no avoiding either case in our tanks, so all methods are in both locations really.

One of the few research papers of root vs shoot preference showed no differences between root vs shoot source of ferts, they even cut the roots off and the shoot had the same relative growth rate.

Large root systems do not imply root uptake preference also, it could be they are from streams where they need strong roots for anchorage, or the roots act as storage organs(much more likely the case with swords and Crypts) or for when water levels drop and they need a source of water etc. None of these possible reasons imply anything about uptake of ferts from the sediment.


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## FlyingHellFish (Nov 5, 2011)

^

Is it not the roots that take up the majority of the nutrients? Don't plants prefer their roots and don't they take up more nutrients that way? Leafs capture the light and roots take up the nutrients? In nature, where would the nutrients most likely be? In the water column or the sediments? 

We know water column fertilizing works, you have great tanks but I'm curious about the many different "route" people take. What about the Europeans and Asian market, where they focus more on a rich substrate and lean column? 

By dosing the water column, are we not just enriching the high CEC substrate? Could we not just go with a rich substrate that slowly provides the nutrients like ADA's power sand?


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## Diana (Jan 14, 2010)

Land plants take up almost all their nutrients via root because that is where the ferts are. In the soil. They CAN take in ferts via their leaves. Google 'Foliar Fertilizer' for more info. 

Aquatic plants are quite good at taking in nutrients both ways, leaf and root. While there may be some ferts that seem to be accepted better via one method or the other, this is only in the lab where the water and soil are kept separate. (Complex set up.)

Tom is absolutely right about our aquariums: The ferts end up all over the place (water and substrate) no matter how you dose. 
Method of dosing is up to you. 

If you have a substrate with high cationic exchange capacity (clay, humus) then there is an added cushion, a reserve. These substrates hold on to the fertilizers in a way that the plants can take them when needed. So if you are dosing just water column ferts you are still building up a reserve in the substrate. It does not matter if you start with a nutrient loaded substrate, or a sterile substrate. If it has good CEC it will attract and hold the fertilizer. 

Your substrate (sand, gravel, other coarse materials) does not have high CEC, though it can build up as the organic matter decomposes. You will need to stay right on top of scheduled dosing to keep the fertilizer supply constant. After a while the fish waste, dead root and so on will be breaking down, and (if you do not deep vacuume) will build up some humus (finely decomposed organic matter) which has high CEC. So gradually your tank will build a reserve capacity. 

I think I would add some slow release tablets deep in the substrate. 

No matter which way you go-
Extra fertilizer in the original substrate
High CEC material but no ferts in the bag
Low CEC

you will have to add fertilizers as your plants grow. 

Substrate is like your plates and bowls. It holds food, it is not itself food. 
Fertilizer is the food on those plates and bowls. It gets used up and needs to be constantly added.


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## Makenga (Jun 30, 2013)

This is very helpful. Since I have a couple lifetime's worth of dry fertilizer I am going to leave my substrate as is pretty much and focus on the water column. Thanks for the replies everyone, support on this sight is top notch.


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## Monster Fish (Mar 15, 2011)

Well said Diana. I find with my experience with various inert substrates, that you can use whatever you want for the substrate and keep the plants healthy as long as there's a source of nutrients, either in the substrate, water column, or both.


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## rwong2k (Dec 24, 2004)

wow great posts, I didn't know that about fertilizing at the substrate/roots vs. water column!


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## FlyingHellFish (Nov 5, 2011)

Thanks for the explanation Diana, I'm curious as to why there is not a central "method". Maybe I'm asking the wrong questions, it certainly feels like I'm no where close to understanding the mechanics behind it. One method would work great in one tank, while another I have to completely redo. 

I have read that the preference of either root or water column depends on the nutrients as well and that plants have "reserve" that they can use. 

So forgive the ignorance, this is a hobby to me and I'm doing quite a lot of reading. Maybe I'm reading the wrong stuff.


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