Re: [APD] (correction)The siphon saga continues...need safety shutoff!

[Rod Gerrymander <rgerrymander at yahoo_com>]

I AM using siphons that are not in overflow boxes, 
and they go as deep into the tanks as possible.  They
ARE uncontrolled, and will continue to siphon if the
power goes out.

That is all okay, because the tanks are all at
approximately the same level and when the power goes
off all tanks will end up with the same water level
and none of them will overflow.

I really just have to make sure that the siphons 
never fail, because the pump, which is also low in
the big tank, will just keep on pumping and pump all
that water all over the floor.

There are two reasons for failed siphons that I can
see.  One is bubbles breaking the siphon.  From my
field experience over the last week I draw two
conclusions.  (1) as someone just posted, the bubbles
arise spontaneously in the siphon tube and are not
pearling bubbles drawn in with the water.  (2) A
higher flow rate essentially ends the problem.  I
went from 1.25 in siphons to 0.75 in siphons and
have not seen a bubble since.  However, there is still
a danger of bubbles collecting and breaking the
siphon during a long power outage.  The only solution
for this seems to be AquaLifters.  I have two on
order but they have not been shipped yet.

The other problem is the siphon intakes being clogged.
My solution for that, not yet implemented, is to 
build a branching intake structure with many input
points widely separated (these tanks are part of 
the workings of the main tank and are not for show).

It occurs to me that using an overflow box on the
main tank would be a form of safety shutoff.  The
main tank could not empty out enough to overflow
the service tanks, even if a siphon shut down.  The
only risk is an overheated pump, and I am prepared
to risk that.

I have really appreciated the discussion on this
issue.  You guys are great.

Thanks,
Rod

--- revance at indiana_edu wrote:
> I just want to correct myself... I see what you mean
> about the evaporation. 
> The water levels should be roughly the same in the
> inside and outside box, so 
> if the water level starts to drop in the tube around
> the second siphon in the 
> skimmer box it will replenish itself from the other
> side. For this to work you 
> need to make sure your siphon tube goes far enough
> down on the skimmer side.
> 
> 
> Quoting Laura Burbage <leuhrich at yahoo_com>:
> 
> > If I remember correctly, the air was getting into
> the
> > siphon because the plants were pearling a lot, no?
>  If
> > this is the case, then the part of the skimmer box
> > that resides _inside_ the tank will keep out the
> > bubbles.  The bubbles would go around it, and
> break at
> > the water surface, while surface water overflows
> into
> > the skimmer box.  Even if a few bubbles did get
> into
> > the skimmer box, they would still stay at the top
> (and
> > break), while the intake for the siphon is a few
> > inches lower.  The inside skimmer box is also what
> > keeps your tank from draining if the pump should
> stop
> > (the water level falls below the top surface of
> the
> > box and ceases to drain into it).  Oh! and a
> really
> > good point that I didn't think of was that both
> > siphons could drain to the same outside overflow
> box,
> > preventing water from evaporating from it. If the
> > second inside skimmer box is higher than the
> first,
> > the siphon will just sit there on call until
> needed.
> > 
> > OK, really primitive drawing below to show the
> path of
> > the bubbles that are currently getting in the
> siphon.
> > 
> > -Laura
> > 
> >               siphon
> >           ______________
> >    inside | __________  |
> >       box | |         | |
> > ~~~:~~~|~~| |~~|~! |  | |      |
> >    : . |  | |  | ! |  | |      |
> >       .|_______| ! |~~| |~| |~~|
> >         . .      ! |  | | | |  | outside overflow
> box
> >  tank      :     ! |______| |__|
> >            :     !        | |
> >            :     !        | |
> >         bubbles  !        to sump
> >            :     !
> > WWWWWWWWWWWWWWWWW!    
> > 
> > 
> > 
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