When I add oyster feast my sump gurgles at the drain from display, what causes this?

[kurfer]

I turn off my reef octo protein skimmer, take a turkey baster and blast my acro's with my oyster feast/salt water mix.

Within seconds the sump starts making a gurgling sound which is fairly loud very bubbly and then stops. Once I turn my skimmer back on 10-15 minutes later it's like nothing ever happened.

I could understand the noise coming from the skimmer as I add food to the water but can't for the life of my figure out the reason the drain into the sump makes this noise only after feeding oyster feast.

[degibson84]

are you shutting your return off as well?

[kurfer]

are you shutting your return off as well?

No, just the skimmer.

[jmeehan]

It is probably because the skimmer dumps its water into the sump when it's turned off.

[Donkeykong]

My guess is that the water level in your sump rises when you turn your skimmer off, causing the drain to enter in at a different height that causes the gurgling.

[kurfer]

Hm..makes sense but the sound goes on for close to 15 mins. :(

[kurfer]

My guess is that the water level in your sump rises when you turn your skimmer off, causing the drain to enter in at a different height that causes the gurgling.

Ahh I think this must be it!

[a.browning]

My guess is that the water level in your sump rises when you turn your skimmer off, causing the drain to enter in at a different height that causes the gurgling.

This is what I would think.

[Animadverto]

I've tried dosing oyster feast with the skimmer on and off trying to see which way would stop the gurgling, and it made absolutely no difference. The gurgling didn't stop until I turned the return pump off, which led me to believe that it had more to do with the correlation of surface tension and viscosity of the oyster feast affecting the viscous resistance of the flow of liquid down the drain pipe which probably caused the gurgling noise.

This seems to be consistent with Poiseuille's Law. http://hyperphysics.phy-astr.gsu.edu/hbase/ppois.html

[dkeller_nc]

The gurgling didn't stop until I turned the return pump off, which led me to believe that it had more to do with the correlation of surface tension and viscosity of the oyster feast affecting the viscous resistance of the flow of liquid down the drain pipe which probably caused the gurgling noise.

This seems to be consistent with Poiseuille's Law. http://hyperphysics.phy-astr.gsu.edu/hbase/ppois.html

This, by the way, is the correct explanation. Oyster Feast contains a ton of fatty acids that drop the surface tension and interrupts the smooth flow of water over overflows and down drain pipes (though it doesn't appreciably affect the viscosity of the tank water, just the surface tension). A skimmer will rapidly remove these surface-active compounds, and therefore restores the smooth flow of water within a few minutes.