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Plant Tanks, Heating Cables, and Heart Attacks - 10/19/2006
<<Hi, Arthur. Tom here.>>
Hopefully you can help ease my mind. I am setting up a freshwater planted
aquarium and intend to use heating cables submerged in the substrate. Is there
any way whatsoever I could be harmed by the following:
The cables are powered by a step down isolation transformer with 115 VAC input
and drawing 2.46 amps on the input side with a max load of 270 watts protected
by a 4.0 amp super time - Lag TT fuse.
The transformer powers a heavy duty submerged silicone cable manufactured by
Dupla at 48 volts and 6.43 amps on the output side.
The statistics I have read indicate the skin give between 2000-50000 ohms of
resistance, but a inside the skin only provides 500 ohms. It seems to me that
should the cable become cut and exposed, and I happened to stick my arm in with
a cut, I would potentially be able to run 96 milliamps through my body (48 volts
/ 500 ohms)? I have heard that 30 milliamps through the heart can cause cardiac
arrest. Does this seem like sound reasoning? The product in question guarantees
absolute safety, but I would appreciate opinions by those with more electrical
knowledge.
Finally, I do use a GFCI, but as I mentioned, this is an isolation transformer.
I also will be using a titanium grounding probe. Also, the company is a niche
German aquarium company, and I am unable to get any useful information from
them.
<<Arthur, this strikes me as more than mere concern. Frankly, I’m in less of a
position to assure your absolute safety than the manufacturer would be but,
based on product stat’s you’ve provided, I would suggest that a potentially
dangerous situation while using this product is remote at best. Three options I
would suggest would be, first, unplug the heater any time you need to place your
hand/arm in the tank. Second, if you do place your hand/arm in the tank with the
heater on, keep your other hand/arm out of the tank. Electricity cannot pass
through your heart unless there exists a complete circuit through your body.
Third, don’t use this product, which is the only fool-proof way not to get
“zapped” by it. Tom>>
Using Reptile Heaters To Heat An Aquarium -
09/13/06
Hi WWM crew. First of all, thanks to Chuck for his input and
cautions.
The advice was much appreciated, and I'm now revising my stocking
list accordingly.
I was reading a number of FAQs on WWM (and other sites) regarding
the issue of substrate heating in FW plant tanks. And was debating
whether or not it was worth it. However, the one thing that kept
popping up was people discussing how annoying they are to deal with.
At first this seemed strange to me until I realized that most of the
heat cable devices are designed to go IN the substrate. Yikes! This
was not my intention when I first read/heard about the idea. I have
a number of heating devices (heat pads, terrestrial heat cables,
etc.) left over from keeping various reptiles, and my intention was
to attach whichever one fit best on the outside of the tank
(underneath the substrate) using silicone or electrical tape. I then
planned on hooking it up to a rheostat (also left over from reptile
keeping) and tinkering with that until the substrate surface at 1.5"
read 78 degrees. These numbers are based on a water temp. of 76
degrees and a total substrate depth of 3".
Do you see anything horribly wrong with this plan? All the devices
in question are safe for use in high humidity and the tank's stand
has an open top for use with overflows and such. So the safety
issues should be covered. I'm still deciding whether or not it's
worth another outlet, but wanted to check to see if this method
would be acceptable for reaping the "benefits" of a heated substrate
or if you have to have the cables IN the substrate. If that's the
case... I might leave that idea by the roadside. Thank you all again
for your time and dedication.
-Tyler
< Check with the manufacturers of the products to see if they can be
used for this purpose. If one of these products caused a hot spot
under the aquarium it could break or crack the glass if there is too
big a temperature differential. Who is then responsible for the
damage? If it was heating the water then warmer water would rise in
the tank and be replaced with cooler water. Under the gravel you
have restricted water flow and the circulation may not be enough to
cool the glass. It would not be worth it for me and I would purchase
a high quality heater.-Chuck>
HEATING COILS IN A FRESHWATER PLANT TANK
I am setting up a 30 gallon fresh water planted tank.
I just finished installing an under gravel heater made by Hydor. I am fairly
certain that their heater cable is just for warming the gravel to improve
water flow around the plant roots and not to heat the entire water column. I was
also going to install at least one standard 100W Jager water heater. The heater
cable is connected to a temperature probe that mounts in the water column and
controls a thermostat powering the cable.
My question is what temperature should I set the cable thermostat to? If I
set it at the same temp as the Jager water heater will the gravel heater ever
come on (i.e., since the water column is always at that temp)?
<Depending on how thick the gravel layer and the porosity of the substrate you could have a significant temperature differential between the substrate and the ambient tank water. Place a sinking thermometer at the bottom of the tank buried in the sand and another floating thermometer at the top of the tank. Read the difference. In order for water to flow from the gravel up to the tank it needs to be warmer than the existing tank temperature to rise up through the sand and create a flow. I would set the water temp at 78 degrees and the cable at 80 and monitor the temps.>
If I set the gravel heater a few degrees higher won't the gravel heater always be on until the water reaches the temp set on the gravel heater?
<If the tank water temp is higher then you are wasting your time and money on these cables.>
The instructions with the cable are obviously lacking any help. Thanks if you can help with this
problem. Also would a small UV sterilizer be valuable in keeping my investment disease
free? I will be running an Eheim canister filter.
John Malenchek
< A UV sterilizer helps but there are no guarantees. I would invest in a quarantine tank myself and be a little patient.-Chuck>
Substrate heating
Hello Robert,
The argument for substrate heating in FW planted tanks is that the
slow H2O column exchange within (as the bottom is typically 1-2degrees
warmer than the column itself) will help the gravel "sweet" for a
longer
time than without it. There are other arguments for it as well (though
they focus on the needs of the plants themselves).
<Yes>
I know that some people will try to heat the whole tank with the
cables, though I have had good luck using them for warming the substrate
only.
I am convinced that my 5 inch "deep sand bed" is providing
denitrifying benefits in my planted discus tank, though I have no #'s to
substantiate this (what do you think?).
<I think you are probably correct... I would do the same.>
Since the the substrate depths between a typical planted tank/reef
tank are roughly similiar, in your opinion why don't we see cables
used?
<Mostly the expense involved... along with basic ignorance... folks don't
know... it took me decades of "campaigning" to help raise skimmer,
cyanide... issues. The "founder effect" in the hobby is greatly slowed
by its huge "turnover" rate... most folks don't last a year as
aquarists>
Maybe we could use DSB's in our display tanks this way, not
having to worry about anaerobic conditions so much? Have cables been
used in the past?
<Yes and yes. Not that uncommon in Western Europe for instance>
Thank You, Erik Nelson
P.S. BTW, for the occasional hydrogen sulfide pockets that do appear
(mostly around a dead rhizome), I think my pair of Golden Dojo Loaches
actually like the smell! They remind me of a couple of naughty dogs in
the garbage can!
<Again, agreed! You should memorialize your keen observations, have them
published at least as feature articles in the hobby magazines. Do consider this.
Bob Fenner>
substrate cables again (note: add link)
Hi Bob,
Sorry---I forgot one thing in my last E-mail to you.
In the substrate section of the plants section of your site, under
"Further Reading" could you please list a ref. to "www.thekrib.com"?
This is THE website for planted aquaria!!!
<Ahh, will do so on the moving about of your message here. Do have this site
listed on our "Links Pages"... a real winner. Bob Fenner>
Re: Temperature
Dear Robert,
My son-in-law likes to keep the temperature at about 72 f. He claims that
tropical fish like warm water. I maintain that such high temperature breeds
bacteria, nitrite, ammonia etc.
I contend that he should lower the temperature.
<Mmm, a tough general question...>
Could you please advise us what is the ideal temperature for tropical fish?
<Depends on species, gear involved, the aquarists wishes (more rapid growth, but more money for filtration, aeration, lighting...)... but something in the mid to upper seventies F. is "about right" for the broad mix of "tropical" fishes offered in our interest. Lower temperatures (lower seventies, upper sixties F.) are tolerable to many species identified as "tropical", and keeping temperatures lower is more "safe" in terms of induced metabolic rates, dissolved gas concentrations, higher stocking densities, costs of operation... but most folks would rather see their fishes, invertebrates moving about more briskly, more colorful, growing faster, reproducing... most often tied in with warmer water. If, where in doubt, by species, you can find useful information on temperature range of many species (in the wild) posted on www.Fishbase.org
Bob Fenner>
Thank you, and best regards
Joe Carabott
Is the tank too tall ?
My girlfriend is planning out a freshwater tank (55 gal.) to be used for
freshwater plants. She is planning to put various sword plants, grassy
plants, some slender spike rush. The tank is 23 in. tall. Will she be
alright with 3 40w. fluorescent bulbs or should she go with a 220watt
power compact system because of the depth of the tank?
Also, do you think underwater heating pads are a necessity or are they
just a pain in the *&#@?
>>
Wow, a plan, and such planning! Sounds like you two are candidates for my "favorite types of fellow hobbyists". I would definitely go with the compact fluorescents if this were my tank... and maybe build it and the canopy to house it as something that can be raised/lowered over the top of this tank...
Heating the substrates of planted systems does have its advantages... especially in cold room settings, with very tropical plants... but for your application, I'd look into using a slow-circulated undergravel plate arrangement with a heater for the tank at one end... enclosed by a riser... and a simple, slow air-lift at the other... pulling the warm water gently under the plants, substrate. This and other heating strategies for planted tanks can be found archived at the URL:www.wetwebmedia.com
Bob Fenner
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