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Re: RFUG's
"II, Thomas Barr" wrote:
<snip>
>work and I got proof<g> but your notion of slow fertilizing in the substrate
>won't apply then. Nutrients come mainly from water column and bacteria in
>the substrate.
<snip>
Tom,
I really appreciated your insights on the RUGF idea. On the specific issue of
slow fertilizing, I thought that the concept would work only if complemented
by a high CEC substrate material. As I understand, the idea is to force the
nutrient-rich water to first flow thru a substrate layer where the nutrients
have a chance of being captured. The flow must be very low, on the order of
a few quarts / hour perhaps. The water that leaves the substrate into the
water column would be not as rich in nutrients, helping to starve the algae.
At the same time, the constantly replenished water would prevent the buildup
of anaerobic conditions.
To this end I built the substrate in my aquarium using a full 11 qt. pack
of vermiculite (crushed a la Jim Kelly recipe) in the bottom layer, right
on top of the plate. I have two observations that may be related to the
issue:
1 - there are about 20 plant species in the tank, and fish well above the
canonical 1 inch/gal rule. All the rooted plants grow very well. But plants
that feed directly on water just survive: Java fern, Java fern tropica,
Java moss, bolbitis, all rooted in driftwood/lava. They don't die but don't
grow to much either. Actually their leaves don't grow much, but their fine,
filamentous, brownish roots that feed in the water do grow well. There are
specimens in both low and high light areas. I also keep the same plants in
a separate, fishless tank, rooted in driftwood and with strong water
circulation, fed by the same PMDD regimen with additional KNO3 and some
phosphorous, and they grow like crazy. This tank is low light, no CO2, as
oposed to the main tank with 3 watt/g and yeast CO2. Both tanks are almost
algae-free.
2 - My Seachem iron test kit never measured any iron in the aquarium, despite
that it is capable of measuring low levels in a test solution made with the
same PMDD used in the tank.
Both facts are consistent with the idea that the substrate is really capturing
part of the nutrients and starving the water column. But only a controlled
experiment could settle this, I guess.
Nice pictures too ! What are the lights in pictures 45-52 ? They look
very similar to track lighting I have in my basement.
-Ivo Busko
Baltimore, MD