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Re: Surface skimming, sumps, floods

On Mon, 12 Jul 1999, Joseph R. Sachleben wrote:

> I have found some information on the Krib site. Erik Olson
> has an entry in the Krib archives dated Oct 98. Most of
> what he says is clear, but he also wrote, 
>     To keep the water returns from back-siphoning
>     everything out of the tank during a power outage,
>     I have small holes drilled near the top that will
>     break the siphon.
> I know you're out there Erik. How do you prevent water from 
> squirting out these holes when the pumps are one? 

I don't.  The holes are right at the surface or just below, so there's not
really a lot of "squirting" per se.  I do have problems with this, because
the holes eventually clog up with algae and crud... I've been playing with
a newer design that uses PVC and ping pong balls to break the backsiphon
when the power turns off... it's been marginally succesful.

> If you are
> using a siphon to take water out of the overflow, how do you
> get the siphon restarted after the power goes out? I seems that
> you would pump the sump dry and ruin your pump.

The basic idea is that you have the tank on one side, a small tank on the
other side with an overflow standpipe, and a siphon connecting them.  When
power fails, water drains only down to the level of the standpipe, so the
siphon does not break.

I have a diagram of the overflow skimmer I built at
Its main advantage is that it uses an aquaclear-300 sponge as its
prefilter.  It has many disadvantages too, which I mentioned in the

Many other people have created overflow skimmers utilizing the same basic
priciples (see http://www.thekrib.com/Filters/overflow-skimmer.html for
some examples).

  - Erik

Erik Olson
erik at thekrib dot com