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So-called "Heavy Root Feeders" - Fact or Fiction??

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Lately it seems like there's been a lot of debate whether plants like swords and crypts, etc, actually need root supplements, or will do just as well with only water column dosing. I've always taken it for granted that they did need it, but Ive never actually tried any of them without it.

Inspired by a recent idea from Hoppy in this thread , I decided to set up an experimental tank and try to find out if "heavy root feeders" actually deserve the name.

The Plan is to divide a standard 20 long in half at the substrate level, using a 4" tall piece of plexiglass, siliconed in place. Both halves will be inert Black Diamond blasting sand. One side will have a heavy application of Osmocote Plus, the other side will have nothing. Use the same plants on both sides, EI ferts, CO2, medium lighting....and let's see what happens!


Here's the empty tank with divider siliconed in place. I though it was important to have it sealed around the edges, otherwise roots could creep through the cracks from one side to the other.





The Substrate: On the left is brand new blasting sand, never been used, with nothing added to it. For the right side, I put down about 1/2" of sand first, then loose Osmocote Plus, then added the rest of the sand on top.






Depth is about 2 1/2" in front, and about 3 1/4" or so at the back.

*Note: The right side is sand I had already from another tank. There's about 20% regular black aquarium gravel mixed in. It sifts to the top so it looks like there's more than it really is. I dont think it will be a factor.


All planted -




Plant List:

(Left to Right)
Back row - Argentine swords, A. reineckii (not the mini)
Middle row - Crypts: Green Gecko, and Im not sure on the next two. I think a Wendtii red or bronze, and a Wendtii brown. Hygrophila var compact.
Front row: S. repens, DHG, P. helferi

Both halves are identical.

The four swords are all babies off the same runner.




Filtration: Dual Aquaclear 20s. They were both running and cycled, so hopefully any nts/diatoms etc can be avoided.

Ferts: EI via liquid solution mixed per Zorfox's recipe for 20 gal.

Lighting: Two T8s in a homemade box with pretty good reflectors.

One Hagen Life-glo, and a 5000K "plant bulb" from Wal-mart.





60-ish PAR seems about right. It's a little less on each end because the bulbs are only 24" long (tank is 30"). Hopefully the stauro wont mind being in the 40s. It's about the same front to back, very little difference.


CO2: DIY sugar/yeast, using two 2 liter bottles diffused via both Aquaclear filters.




Chopstick pre-diffuser -






The system should be legit as long as I change one bottle every week and dont get lazy. Ive ran this same type set-up on a few tanks now - all with way more than 60 PAR. For more details like how the bottles are sealed, etc, see the diy link my sig.

I'll take some PH readings in a day or so to see what kind of drop is going on.

Livestock: About 20 guppy fry from two different sets of parents....and a handful of snails. Im hoping the snail population establishes. I like snails as long as they dont get outta control. :)


More pics:

Left Side






Right Side






FTS




So that's where it stands as of now - day 1.

Hopefully this will turn out to be useful and interesting. I'll try to post updates every week or so.
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Just curious, what does the "plus" include in Osmocote plus? I have a big bottle of regular Osmocote and while I have never used it in an aquarium I found it ineffective at growing flowers in the garden. My local garden dude turned me on to some stuff called "Garden Cote 6" which makes my flowers bloom like crazy. He claimed that when Osmocote was bought out a few years back that they removed some of the more expensive micros but I have nothing but his word for that. There are a few things in the Garden cote that are not in regular Osmocote so I was just curious if that was what the plus was.
 

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Osmocoat will leach out and fertilize the entire tank. Also, EI is not non limiting, that's a bad assumption:wink:

So a tank with say MTS or ADA aqua soil and EI vs a tank with just ADA AS or MTS, or just EI............will have slower rates of growth compared to EI + a rich sediment type.

I do not think anyone has issues growing Crypts or swords really if they take decent general care of them. Large roots, they both come from streams and rivers where they would get washed away. A good reason to have large roots.
Then once the water recedes........they are left high and dry.........they need a strong root system for nutrients/water uptake.

Both Genera have rhizomal type roots and runners, good for storage and resprouting, ability to send runners to better habitat locally and to over winter long droughts/adverse conditions.

A simpler test is to use a sponge at the neck of a flask to place the plant's crown in and add fertilizer in the flask or not.........then add a non limiting fertilizer to the water column. This keeps the root fertilizers separated and the roots isolated. While providing plenty of nutrients to the leaves.

The other simple thing to do, cut off the roots and see if the rates of growth are the same in rich sediment with rich water column.

http://www.prirodni-akvarium.cz/en/...ophytes growing in a nutrient-rich stream.pdf
 

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Osmocoat will leach out and fertilize the entire tank. Also, EI is not non limiting, that's a bad assumption:wink:

So a tank with say MTS or ADA aqua soil and EI vs a tank with just ADA AS or MTS, or just EI............will have slower rates of growth compared to EI + a rich sediment type.

I do not think anyone has issues growing Crypts or swords really if they take decent general care of them. Large roots, they both come from streams and rivers where they would get washed away. A good reason to have large roots.
Then once the water recedes........they are left high and dry.........they need a strong root system for nutrients/water uptake.

Both Genera have rhizomal type roots and runners, good for storage and resprouting, ability to send runners to better habitat locally and to over winter long droughts/adverse conditions.

A simpler test is to use a sponge at the neck of a flask to place the plant's crown in and add fertilizer in the flask or not.........then add a non limiting fertilizer to the water column. This keeps the root fertilizers separated and the roots isolated. While providing plenty of nutrients to the leaves.

The other simple thing to do, cut off the roots and see if the rates of growth are the same in rich sediment with rich water column.

http://www.prirodni-akvarium.cz/en/...ophytes growing in a nutrient-rich stream.pdf

Thank's for the link Tom:)
 

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This should be interesting! Both sides should have very nearly the same water column nutrients, but the Osmocote side should have more nutrients available to the roots, but it might not be much more. The substrates are in water, so nutrients can migrate both ways - into the water and from the water to the substrate. So, if the growths are nearly identical between the two sides it might show that the leaf feeding is adequate for the "heavy root feeders", but it might also show that nutrients migrate between the substrate and water freely enough to feed the roots even though there is no substrate fertilizer there.

This is kind of like the NASA efforts to find evidence of life on MARS - once the experiment gives positive results, you have to make sure those results can't have occurred for reasons other than what you were trying to prove.

That just makes it more interesting!
 

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Nice start on an interesting experiment. Lots of possible future permutations including high CEC substrates with/without root feeding, low water column fert addition with/without root feeding, and macro+micro tabs (osmocote) versus micros only (Flourish Tabs).

Wild prediction: at least one plant species will do poorly with the Osmocote due to ammonia burn.
 

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Discussion Starter · #18 · (Edited)
Osmocoat will leach out and fertilize the entire tank.
Thanks Tom for the always valuable info. :)

Regarding the quoted part: I understand that, but does it even matter? The leeched out nutrients should be the same as any other water column ferts at that point, right?

This should be interesting! Both sides should have very nearly the same water column nutrients, but the Osmocote side should have more nutrients available to the roots, but it might not be much more. The substrates are in water, so nutrients can migrate both ways - into the water and from the water to the substrate. So, if the growths are nearly identical between the two sides it might show that the leaf feeding is adequate for the "heavy root feeders", but it might also show that nutrients migrate between the substrate and water freely enough to feed the roots even though there is no substrate fertilizer there.
I thought about that too. If both sides do well, even though we may not know for sure if they fed from the roots or the water column, it will still serve to illustrate they dont really need root ferts when there is an ample supply in the water. Which is the primary question the experiment is trying to answer.

Thanks again for suggesting something like this in that other thread. You actually gave me the idea for this incredibly fun experiment. :)

Wild prediction: at least one plant species will do poorly with the Osmocote due to ammonia burn.
Haha, I did use quite a bit. Actually I removed maybe 10% after those pics were taken because it looked like such a whopping amount. :icon_eek: So there's not quite as much as what's in the pics.

I've done about this much a few time under a specific area for carpeting plants with good results, but never a whole tank's worth, or in this case half a tank's worth. Time will tell.....
 

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Believe the Osmocote will take some time to begin leaching nutrient's(slow release) compared to water column dosing which would work faster for plant's benefit.
I am advocate for both substrate loading/feeding and water column dosing together for it produces the result's I want.
Plant's are in win/win situation and so long as too much light is not used,,leaves only CO2 to get right.
 

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I hope you will take a photo of the tank every week to 10 days and post them, so we can follow the progress.

Rarely does a single experiment prove much. Proof of something usually take numerous different experiments. But, this should be able to show that the plants you are using can be grown well, equally well, almost as well, etc. whether you use substrate fertilizing or not, as long as you are dosing the water column adequately.
 
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