Closed Loop Question

[Brian Kramer]

I can't figure out why I am getting microbubbles on my closed loop
with a scwd run by a lg 3mqdx...it's about a 1000gph pump.

Here's the schematic:




Output is all 3/4 pvc except for the connections to the scwd which is
tubing.
It is slightly offcentered (i.e. one of the output sides is a little
longer than the other to get around a skimmer.

The input in the tank has a 1 1/2 screen to a 1 1/4 reducer to a elbow
back to a tee which goes up with a cap for repriming. Then down to an
elbow and reduced to 1 inch pipe to the pump.

Unless I throttle it way back I get a lot of microbubbles..even
throttled down 1/3 on output I still get some.

Any ideas on what I could do.

[Marc Levenson]

Brian, did you glue everything? Did you use teflon tape on the threads?

Does the intake section have the ability to suck air in at all?

Do the returns have anti-siphon holes drilled? (They shouldn't).

Did you try turning off the pump for 15 seconds, then restart?

Marc


Brian Kramer wrote:

> I can't figure out why I am getting microbubbles on my closed loop
> with a scwd run by a lg 3mqdx...it's about a 1000gph pump.
>
> Here's the schematic:
>
> Output is all 3/4 pvc except for the connections to the scwd which is
> tubing.
> It is slightly offcentered (i.e. one of the output sides is a little
> longer than the other to get around a skimmer.
>
> The input in the tank has a 1 1/2 screen to a 1 1/4 reducer to a elbow
> back to a tee which goes up with a cap for repriming. Then down to an
> elbow and reduced to 1 inch pipe to the pump.
>
> Unless I throttle it way back I get a lot of microbubbles..even
> throttled down 1/3 on output I still get some.
>
> Any ideas on what I could do.

--
Personal Page: http://www.sparklingfloorservice.com/oanda/index.html
Business Page: http://www.sparklingfloorservice.com
Marine Hobbyist: http://www.melevsreef.com

[Brian Kramer]

Everyting above/out of the water is glued and taped. Some in the
water are not glued and taped to allow adjustments. No anti siphon
holes. I don't think there are any places where it can suck air.
I'll try restarting it. I guess I could silicon the joints as well to
make sure there is no way for air to get in on the intake. I do hear
a gurgle every 5-10 seconds though...but I can't make the intake any
bigger....

Marc Levenson > wrote in message >...
> Brian, did you glue everything? Did you use teflon tape on the threads?
>
> Does the intake section have the ability to suck air in at all?
>
> Do the returns have anti-siphon holes drilled? (They shouldn't).
>
> Did you try turning off the pump for 15 seconds, then restart?
>
> Marc
>
>
> Brian Kramer wrote:
>
> > I can't figure out why I am getting microbubbles on my closed loop
> > with a scwd run by a lg 3mqdx...it's about a 1000gph pump.
> >
> > Here's the schematic:
> >
> > Output is all 3/4 pvc except for the connections to the scwd which is
> > tubing.
> > It is slightly offcentered (i.e. one of the output sides is a little
> > longer than the other to get around a skimmer.
> >
> > The input in the tank has a 1 1/2 screen to a 1 1/4 reducer to a elbow
> > back to a tee which goes up with a cap for repriming. Then down to an
> > elbow and reduced to 1 inch pipe to the pump.
> >
> > Unless I throttle it way back I get a lot of microbubbles..even
> > throttled down 1/3 on output I still get some.
> >
> > Any ideas on what I could do.

[Marc Levenson]

By any chance could your intake basket be siphoning some air (via a tiny whirlpool)?

My closed loop runs silently, but if it does make noise, it is due to cavitation (air
bubbles in the pump's chamber) and I unplug it to allow the air to rise out of the pump. 5
to 10 seconds later I plug it back in and it is silent.

I doubt silicone will really seal PVC. That is more of a bandaid fix, but if you have a
pinhole leak, then maybe that bandaid will do the trick. :)

Marc


Brian Kramer wrote:

> Everyting above/out of the water is glued and taped. Some in the
> water are not glued and taped to allow adjustments. No anti siphon
> holes. I don't think there are any places where it can suck air.
> I'll try restarting it. I guess I could silicon the joints as well to
> make sure there is no way for air to get in on the intake. I do hear
> a gurgle every 5-10 seconds though...but I can't make the intake any
> bigger....
>
> Marc Levenson > wrote in message >...
> > Brian, did you glue everything? Did you use teflon tape on the threads?
> >
> > Does the intake section have the ability to suck air in at all?
> >
> > Do the returns have anti-siphon holes drilled? (They shouldn't).
> >
> > Did you try turning off the pump for 15 seconds, then restart?
> >
> > Marc
> >
> >
> > Brian Kramer wrote:
> >
> > > I can't figure out why I am getting microbubbles on my closed loop
> > > with a scwd run by a lg 3mqdx...it's about a 1000gph pump.
> > >
> > > Here's the schematic:
> > >
> > > Output is all 3/4 pvc except for the connections to the scwd which is
> > > tubing.
> > > It is slightly offcentered (i.e. one of the output sides is a little
> > > longer than the other to get around a skimmer.
> > >
> > > The input in the tank has a 1 1/2 screen to a 1 1/4 reducer to a elbow
> > > back to a tee which goes up with a cap for repriming. Then down to an
> > > elbow and reduced to 1 inch pipe to the pump.
> > >
> > > Unless I throttle it way back I get a lot of microbubbles..even
> > > throttled down 1/3 on output I still get some.
> > >
> > > Any ideas on what I could do.

--
Personal Page: http://www.sparklingfloorservice.com/oanda/index.html
Business Page: http://www.sparklingfloorservice.com
Marine Hobbyist: http://www.melevsreef.com