"Philip Lewis" wrote in message du...
EM0VE (John) writes:
Something about the ability of the wave forms they generate to
damage equipment if I remember right.
Thats what I read too. Especially with pumps/motors.

It's likely the difference between a UPS with a true sine-wave, vrs a
modified sine wave. (which i believe is a square wave)

AC power from the outlet is true sine-wave. I don't see why a UPS
with a true sine-wave would be different.

The problem with UPS used for a fish tank is that it usually
has too small battery to go for a long time. Also, you are
paying for a main feature you do not need in a reef tank:
UPS is Uninterruptable Power Supply - the power supplying
a personal computer cannot be interrupted because you will
loose data. A short power failure will not harm the fish tank.
So you do not care if after the power out your power supply
will start after a milisecond or a minute - important is to not
let the tank static for longer than an hour...

Instead buying large, expensive UPS dedicated to computer
use much cheaper large marine lead-acid battery together
with a small charger and power inverter. If you want the system
to switch to backup power automaticaly you can use one
relay with 120V/AC coil hooked to the mains to switch your
tank from mains to backup when the relay coil will stop being
energized by the mains voltage. With relay you will have one
short gap of missing power, probably too long for a computer
but good enough for a fish tank... This solution, maybe not
as elegant as self contained UPS will last much, much longer
than any large computer UPS...

If you are not particulary handy with electricity you may want
to check out ready made sump-pump battery backup systems
available in Home Improvement stores - they use same principle
with one difference: all components are closed in one nice
and expensive box :-)