[APD] Re: RFUG revisted

[Thomas Barr <tcbiii at earthlink_net>]

> I was wondering when you'd join the fun.
> 
>> Same substrate?
> 
> Yes and no.  I moved most of them to another tank with what I was told
> was a better substrate for crypts: laterite, litter, and coarse sand.  I did
> also move some of the plants back into the old tank after removing the rug
> and had similar results to the new tank.

So with that in mind, do you think RFUG's and no flow diffusion and cables
provide any dis/adavantages?
 
> The original RUG tank was the only one I kept minimal amounts of
> nutrients in.  The levels were on the order of 2-3ppm NO3 and very little
> PO4.  K and traces were about half of what most of us keep.

>> I found crypts to do very well, despite all the talk and
>> _speculative_comments and assertions that they prefer to root feed etc.

> They do indeed. I've got a tank full of them right now. :)

We agree. Don't tell anyone:-)
 
> Serious questions:  Thinking only physiologically, wouldn't it stand to
> reason that crypts prefer to feed through roots?

Why? If I was a plant and needed N in my leaf tips, why drag up through the
roots, transport it, unload it, and assimilate it when I could take it in
where I need it?
Why spend energy/resources growing roots for uptake or nutrients when I can
get it all over?
Why limit myself to uptake in only one organ(leaf, root etc) location? I am
often submersed at some point, why not take advantage of both cases?

>  Why produce such a huge
> web of them if they didn't really need them?

What other function(s) to the roots of Crypts/Swords perform?
They send out runners, daughter plants, regrow if nibbled down from above.
They are looking for more light, more room, make a larger patch, dominate.

>  Haven't they got all the
> storage capacity they need in their rhizome?

Sure, they also have some in the leaves, they are also storage organs for
nutrients. Consider a plant. The lower leaves that do not get enough light
often get holes, yellow etc, the plants loses the leaf and puts the goodies
into the new leaf where the light is better. Why keep the old one?

> It makes sense that they would
> need an anchor to survive in currents, but then why not just make a bunch of
> thick anchor roots ala Anubias?  All that extra root material would be
> wasted energy, wouldn't it?

No, also adaptation to currents, often includes scouring. If the top layer
is washed away, it's a good idea to have extensive root systems to avoids
being washed away. Some places in the stream might not be washed away so
that one single runner might make it after the flood to make a new colony.
 
>> P) Regarding whether or not the RUGF was more or less effective than UG
>> cables I'm not sure they can really be compared in this case.
> 
> T) They can and have.

I compared the no flow, the cables and the RFUG in terms of flow rates.
The sand was the same etc. The flow rate was the variable(main).
I describe the substrate in terms of flow rates first.
Then I deal with other physical parameters(grain size, surface area etc),
then move on to chemical and biological.
 
>> P) While the concept is the same, the flow from the RUGF was many times
>> greater than a cable could ever be.
> 
> T) Roughly 20000-30000L/day/m^2 vs around 1-10L/day/m^2 with heat vs
> .5L/day/m^2 for plain old diffusion.
 
> Is there a point where flow would become overkill?

Don't know, I assume where the flow lifts the plant roots out of the
substrate.
 
>> If the aquarium had no RUGF and it was a comparison of a strong
>> root system vs. a cable system I would have to say that we'd have something
>> to compare.
> 
> Done it.
> 
> Your comparison was what I was thinking of.

So what would you like to know about it?
I found iron assimilation was better in cable and no flow tanks when dosed
to the substrate. 

To that end, I found iron assimilation to be even even better with
Flourite(vs sand+ laterite or sand alone).
Cables and RFUG's did not have the flourite in the test back then.

The test I did convinced me that cables/RFUG's although good, were not
significantly different enough to warrant their installation based on plant
growth alone. 

I did not have to test the patterns with the Flourite as well since flow
rate was the main question as to how it affects plants growth. Sand is a
better substrate since iron can be added deleted and there's less biological
interactions with the non porous sand grains and the grains are more
consistent in size etc.

Summerized, the processes involved showed to me that the no flow method
worked well. Adding flourite only improved upon what I feel is the better
method and the better substrate material. The issue of flow rate is less
critical.  

I also had tanks with 6C temp differences with the substrate and the water.
I found little difference in the tank's plant growth rates.

Adding cables is a good move for folks with substrates that are very fine
but not too fine since flow rates would decrease. But you can play with
grain size variations, I'll stick with the 2-3mm sand and the flourite/Onyx
etc.   

Regards, 
Tom Barr  
 
> See you in Dallas,
> Phil

I'll be there.



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