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Re: Send me a cable

> Date: Thu, 23 Aug 2001 17:27:06 -0700 (PDT)
> From: "S. Hieber" <shieber at yahoo_com>
> Subject: Re: cables
> Tom Barr wrote:
> "I had the cables
> on/off for 15 min intervals with basic 2-3mm sand laterite mix at 4
> inch
> depth and 2 watts a gallon/CO2."
> Where you able to notice convection?

Oh yea, I SAW that:) Not really but I was not really looking. I looked at
the plants. An observation about cable tanks though is there was a lack of
algae compared to some other tanks in the start up(likley from trapping
nutrients in the substrate faster via laterite/bacteria). But even if you
used a lower plant density in the start up things came out better.
So I tried it on a clients tanks that Dupla cables prior. Addedflourite and
he less algae problems. Why? Not certain but my guess is the larger grain
sizes and porous nature of flourite allowed waste/nutrient transfers. Too
small of grain sizes may cause some problems with flows. But treying out
onyx sand which is much finer than flourite doesn't seem to follow this
issue either. Plants do very well in also. So it's not grain sizes alone, I
You could've added some potassium permangnate and watched it move I
suppose......they do tracers in cave and aquifer systems sometimes or you
could use methylene blue, malachite green etc. I didn't.
> I would have thought that the cables needed to be on longer than that
> to develop enough local heat for convection to occur.  I know in plain
> water, a cable feel very warm if its been on for only 15 minutes.  But
> of  course, it depends on the watts/length of the cable.

It was a 3 volt transformer with very small wire wrapped in tape to give it
rigidity and protection. But remember that it will come on in other 15
minutes....... so it's already "pushed" a wave up and "pulled" a wave down
to replace the one it expelled. It did work and results were excellent. They
were better than the guy's tank that had the finer sand(about 1mm) and the
Dupla system over the two year period I had them. My problem was pulling the
cables up in many tanks. The RFUG's had close to the same results(but I will
say IMO, sorry that's as good as anyone can really say about this issue,
that the cables did do better than RFUG's but not that much) from my
perspective at the time so the cables phased out since I could do anything
to a RFUG substrate without any fear.

Ambient temps certainly play a big role in any assessment of cables. If you
have a cooler room or keep the same temp year round etc, cable will benefit
you I truly believe to a greater extent. If you live where it gets hot and
don't keep it cool by air conditioning etc cable are not for you.

The temp issue got me wondering about a few things. I like Flourite, so I
intentionally tried doing a "cold feet" flourite tank. I did not take
accurate measurements and do a huge deal on it. Too much trouble for such a
small gain if you ask me. I just wanted to see if there was much to it.
Perhaps with a few plants but not with most of them. Slower growth to some
degree but not that big of a deal. The flourite was at least 8 to 15 F
cooler than the water column I'd say. About in the 65-68F or so range. It
was dramatic when you stuck your hand into the gravel pruning. Did not do a
whole lot. So on to a heat pad, again not much gained if any thing besides
what could be attributes to bacterial actions and MET rates alone..........
I could be wrong.
But I'm not THAT wrong if I am:)

I did see a big difference in flourite tanks vs other systems, cables
included. And the cost factor and wide ranges of applications(Cold warm,
neutral, deep 5-6"+, shallow, mixed with other stuff, no need for something
"under there" or to plug in) made it a good switch.

I still have not tried a dupla and flourite mix. I doubt it will ever make
or break any set up I do though:) But if I where to get a cable system it
would be very close to that or something that kept the same height and
stayed in place well under the gravel. I solf off the last customer's cable
system back a couple of years ago. Yep, I'm now cable free.

George has the most experience and close observations on cables that's I've
talked too. I compared them to other systems(RFUG's, flourite, plain old
mulmy gravel etc) rather than with or without. Not sure if he added
peat/soil in the past or not. I did and still do.
I recall asking Claus C. of Tropica about the cable issue. He said they did
do ONE exhaustive test on a cable system. He said the flow rates where too
high using cables. The optimal flow rates in a sub where very close to
having plain sand with nothing else acting on it. But what was the temp and
the ambient temp? I did not ask. Plant types? I did not ask. I would say
that would be rather important along with depths.
I **think** the flow rate he quoted was .49liter/meter squared per DAY. Not

The short of it all is that I use flourite or onyx and add a touch of fine
ground peat and I'm done with it. Personally it works better than cables IMO
and many others. Now I want to know why IT does well.
Tom Barr   

> Scott H.