Looking for a good float switch
 

"mikesb" wrote in message . ..
The problem with the non-mechanical device is the water level must drop 1"
before the switch turns on. I have the reliable Ultra-life float switch
which kicks on when the water level drops no more than an eighth of an inch.
It may be better for the aquarium environment if the fresh water is added in
much smaller amounts.

Well, depending of the volume in your pump section of your sump,
water drop 1" or 1/8" might be neglectible in terms of total
salinity of your system.
I am sure you know that salinity of surface ocean waters fluctuates
quite dynamicaly with every rain on the reef...
There is no need to keep salinity of the tank water perfectly stable.

The simple test to do would be to measure salinity of the tank just
after top off - then after water evaporates to create 1" drop in the
sump, return pump section. Compare two values and you will know
the difference is not important.

Looking for a good float switch
 

He could use two float switches :-)

I use valves and control the drip rate rather than float
switches, but if I were to use a float switch, I would
tend to lean to a nonmechanical because in reef tanks,
there's a lot of growth that likes to get in to things.
But a nonmechanical switch could be less reliable than a
mechanical - depends on the design.

Also anyone looking at the possible errors of such things
should always look at the worst case senerio. Like will it
stick on, or stick off, how many gallons will go in, and such.

Wayne Sallee
Wayne's Pets



Pszemol wrote on 8/13/2006 5:24 PM:
"Roberto Quijalvo" wrote in message
...
Why replace them if they're working?
To find something more reliable.

How do you measure/compare their reliability ?
How can you be sure you do not replace something
reliable with something less reliable?
Just because switch is non-mechanical in a simple
sense does not necesairly mean it is more reliable.

Just because they haven't failed yet,
doesn't mean it won't.

It also does not mean it will.

There are countless tales out there of failed mechanical switches. I
don't have to personally experience the failure to prompt a change.

I would rather protect myself from the failure and build some
extra flood protection (one more, emergency top switch)
than to worry about replacing the current set if it is working.

Of course, that's not to say that the non-mechanical switches may not
have their faults too.

Then you realize this... ok, let's go back to my first question then :-)

Looking for a good float switch
 

"Wayne Sallee" wrote in message ...
He could use two float switches :-)

YES, the top switch would shut down the pump
in case of overflow. I have already said that...
Evenry device can fail - instead of spending
big bucks on the "more reliable" I would rather
invest in an additional protection device agains
of the failure of the main one.

I use valves and control the drip rate rather than float
switches, but if I were to use a float switch, I would
tend to lean to a nonmechanical because in reef tanks,
there's a lot of growth that likes to get in to things.

Growth is limited in unlighted sump, and growth can
be managed with periodic maintenance... If you clean
the switch every month in vinegear it will be ok...
Also, the second switch working as the overfill shut-off
is normally not submerged, so there is no growth there.

But a nonmechanical switch could be less reliable than a
mechanical - depends on the design.

That is true. Mechanical switch usually controls the pump
directly or using simple relay. Non-mechanical solution usually has
a complicated controller board with a lot of electronics, software.
Read: it has A LOT OF VARIABLES which can go wrong.... :-)
In effect, non-mechanical solution can be less reliable!
Against intuition :-)

Also anyone looking at the possible errors of such things
should always look at the worst case senerio. Like will it
stick on, or stick off, how many gallons will go in, and such.

That is why I have my mechanical switch on a timer...
The timer is set to turn the system once per day, for 5 minutes.
During 5 minutes there is not much water pumped throught
thin tubing, so even if the switch will fail, it will not be a disaster
like in the event of whole bucket of freshwater dumped into the sump
and maybe overfilling sump and flooding the wooden floor :-)
Another protection is the second switch on top of the sump.
It will shut the pump in the event of overfilling.

Like Wayne said - it is not enought to install the best switch to
be safe... You need to design your top-off system and think
of any scenario which can happen - power outage, pump
failure, switch failure, overfilling etc... and check if you are
protected against all the likely scenarios.

Looking for a good float switch
 

Evidenced by the many sad experiences of others (a fool learns only from
his own experiences), it's just a matter of time before the failure
occurs with mechanical switches.

It doesn't take much searching to find that these switches do fail. I
don't have to experience it first hand before trying an alternative.

Pszemol wrote:
"Roberto Quijalvo" wrote in message
...

Why replace them if they're working?
To find something more reliable.


How do you measure/compare their reliability ?
How can you be sure you do not replace something
reliable with something less reliable?
Just because switch is non-mechanical in a simple
sense does not necesairly mean it is more reliable.

Just because they haven't failed yet,
doesn't mean it won't.


It also does not mean it will.

There are countless tales out there of failed mechanical switches. I
don't have to personally experience the failure to prompt a change.


I would rather protect myself from the failure and build some
extra flood protection (one more, emergency top switch)
than to worry about replacing the current set if it is working.

Of course, that's not to say that the non-mechanical switches may not
have their faults too.


Then you realize this... ok, let's go back to my first question then :-)


--
Bert Quijalvo
IT Operations - Production Operations
x40694/(303)558-3108

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