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[AGA-Member] Too Much Heat - Substrate Heating Schedule Suggestions?

Greetings, Everyone,


I'm a new AGA member, and I'm getting back into aquaria after not having any
tanks for over 20 years.  I love plants and have set up a new aquarium
(specifics below) with a substrate heating cable, which sounds like a great
idea.  What I neglected to take into account is that lighting has changed
greatly in the past two decades, and the wonderfully bright compact
fluorescents I have now put out so much heat that it's them or the heating
cables as far as heating the tank goes.  I'm trying to figure out the best
way to handle this, and I'm hoping one of you out there can provide me with
some guidance.


So, the setup:


38 gallon R-375 Lifetech aquarium (I found a picture online, although ours
is silver: http://www.aqlogics.com/product.asp?ProductID=6882) 


two 55 watt 50/50 Actinic/10K Jebo compact fluorescent bulbs [the ballast
needed to be replaced right away, so we put in a good quality one, and wired
the bulbs so that one or both can be on]


R-375 submersed aquarium pump, which sends water to a wet/dry filter (with
filter floss and ceramic beads/stones) in the aquarium hood; the water
returns to the tank from the other end of the hood; there is also a bypass
flow with a venturi valve which I have opened on full for aeration


Dupla Thermik 40 watt substrate heating cable, plugged into a Timex heavy
duty timer which can be set by the hour


Eheim Jaeger 150 watt submersible heater set to a lower temperature (for
backup, if needed - and I don't think I'll need it!)


Substrate (total substrate depth, 4 - 4 1/2 inches):

  Layer 1:  1/2 - 3/4" gravel beneath heating cables (~10 kg unwashed

  Layer 2: ~2 kg FertiPlant laterite, ~8 kg FertiPlant Plus, and ~4 kg
unwashed flourite mixed in aquarium by hand

  Layer 3:  14 kg red flourite, washed to remove substantial amount of dust


Just added:  A yeast reactor for CO2 with airline tubing leading to a
fine-bubbling airstone in the tank (following Tarah Nyberg's yeast recipe on
page 26 of The Aquatic Gardner (volume 17, number 2) [I bought back issues
of Planted Aquaria and TAG - I've been learning so much!])


The room with the aquarium is kept in the mid to high 60's (Fahrenheit)
during the day, and about 70-71 at night.  The tank is not close to a
window, so it doesn't receive any direct sunlight.  My goal is to keep the
tank at about 79 degrees.  


On to the obvious: TOO MUCH HEAT!  


The aquarium hood, although sleek and beautiful, has few outlets of any sort
- just two holes about 1 by 2 inches for tubing and wires to exit the
aquarium, and some ventilation slits above the sealed light fixtures.  I
find this appealing because it's attractive and it will keep escape-artist
crustaceans from taking off, but obviously this gives me a problem with heat
dissipation.  My husband and I are trying to figure out how and whether to
mount a small fan in the hood above the lights to draw heat out - I'm sure
we'll figure out something, but it'll be a little while before we get this
all straightened out.  


In the meantime, I've been turning on one light in the morning, about two
hours later turning on the second light as well, then turning off the second
light in the evening (leaving one), and turning that one off at night.  One
or both lights are on probably about 14 hours total per day (based on when
I'd like to be able to see the plants and tank inhabitants - only a few
Amano shrimp right now). 


Current solution:


I've been having the heating cables on during the night, scheduled for three
hours on, one off, one on, one off,  two hours on, and off for the rest of
the day (since the lights heat all-too-well during the day).  Doing this
schedule I've been able to keep the tank between 79-81 throughout the day
and night.  However, I have no idea what makes the most sense in terms of
the heating cable schedule - should I try for every other hour being on
during the night?  Is it a problem to use the heating cable only at night?
Is it worthless to have a heating cable if it can't be used throughout both
the day and the night (not as regards expense - it's bought and installed
already - but in terms of usefulness)?   For those of you who have heating
cables which don't have thermostats, what on/off schedule do you use?  Any
and all input would be very welcome!


Thank you,






Kirsten Klinghammer

Rescue, California, USA



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