On 26 Nov 2006 19:53:48 -0800, wrote:

Hi guys,

Given the current concerns about climate change, we're getting serious
in my household about reducing out energy use . We don't own a car,
and we're renting our flat (so solar hot water etc is out). We've
swapped all our light bulbs for compact fluorescents, and bought a
nice, old fashioned fan for the living room so that we don't have to
use the airconditioner.

We've identified our fish tanks as a large energy sink. We have a 350
litre community tank in the living room, and a pair of 100 litre tanks
in our bedroom. I've done a quick and dirty estimate of their power
usage, as follows (using
http://www.kernsanalysis.com/HeaterCalculator.cgi to calculate heater
power):

Main tank:

Heating - 110W - 964KWh/annum (120x48x60cm tank with 10mm walls
heated to 8 degrees C above ambient (discus))
Lighting - ~200W - 876KWh/annum (2 x 55W CF + 2 x 36W T8 on
electronic ballasts)
Filtration - ~10W - 88KWh/annum (Eheim canister)

Small tanks:

Heating - 150W -1314KWh/annum (Two 60x35x45cm tanks with 6mm walls
heated to 8 degrees C above ambient (discus))
Lighting - ~50W - 219KWh/annum (One 36W T8 on magnetic ballast
shared across both tanks)
Filtration - ~10W - 88KWh/annum (Two small Eheim canisters)

The whole lot adds up to 3.5MWh/annum, or 1.5 tons of CO2 each year,
which is pretty scary.

Anyway, I've been toying with ideas to reduce energy usage. Firstly, I
think I'll remove the T8 fluoros from the big tank, and put AH Supplies
reflectors on the 55W compacts. I calculate that the increase in
reflected light will pretty-much make up for the decrease in power. I
can then knock a few watts off the T8 on the other two tanks by putting
it on an electronic ballast.

After that though, it gets hard. My next thoughts are to double-glaze
the tanks. If I get some 3mm window glass cut, I could space that a
few millimetres off the main glass. It's difficult quantifying what
sort of power saving I'd get, but I'd guess something like 50% is
doable...

Has anyone tried double glazing?

No. The insulating power of double-glazing comes from the sealed
airspace in between the panes. How are you intending to install this?
You'll need a seal not only for insulation but also to avoid drips and
spills getting in between the panes. Make sure you're not going to
end up doing something that could create optical distortions or mess.
That would invalidate the whole point of keeping aquaria IMHO.

Any other ideas?

Lighting is a very significant expense for the planted or marine tank.
more efficient lighting is a good idea. But you can't have your cake
and eat it too. Either you accept the energy consumption or you do
without the light demanding specimens.

Heating becomes more efficient with larger tanks. Either do without
the smaller tanks or upgrade the 2 100l to a single 200l+.

I wouldn't worry about filtration. It would be more efficient with 2
tanks instead of 3. But the energy expense is minor compared to the
other 2 items. And especially compared to all of your other energy
usage during the day, including your computer. Of course I'm of the
mind set that aquaria are luxury items that are inherently wasteful.
But I'm also a cynic that can't grasp any real significance of me
running plus or minus an extra couple hundred watt devices compared to
the current use and waste of the rest of the world.