What causes skimmers to overflow?

[Biff0rz]

So I've had my skimmer dialed in for a bit, nice dry foam near the top. Today while working on the tank and the past week I noticed it has randomly been overflowing. I haven't added or removed anything from the tank. What generally causes overflows?

 

[DivingTheWorld]

The only time mine overflows is from something added to the water. Chemicals like Chemiclean or Fluconazole always cause overflows. Another thing that's caused it in my tank is Banded Trochus snails spawning.

 

[GoVols]

So I've had my skimmer dialed in for a bit, nice dry foam near the top. Today while working on the tank and the past week I noticed it has randomly been overflowing. I haven't added or removed anything from the tank. What generally causes overflows?

Run a Bubble King over here and it stays dialed in like a home's central heat and air.

If the skimmer is a good one and broke in.

Three things come to mind:
1) Chemiclean
2) Coral putty
3) The water level changing up and down around a skimmer

 

[Montiman]

I find that some of my foods will trigger an overflow. Flake food and amino acids cause my skimmer to overflow. Some times other events like a change in water level, a short power outage or return pump outage can cause a temporary overflow.

From my experience. Skimmers that have the water outlet higher up on the skimmer are less prone to overflow. I find that most modern skimmers that have the ultra compact water adjustments built into the bottom of the skimmer can be much less stable.

 

[MichaelReefer]

Things added with really high nutrients can cause it too.

 

[Biokabe]

Certain brands of coral putty (looking at you, CoralCrete!) are hell for skimmers. I made the mistake of using CoralCrete in my tank... it took three water changes + letting 3+ gallons of skimmate flow out into a bucket before it stopped overflowing. Even now, whenever anything disturbs the CoralCrete, the skimmer will overflow for another week or more.

 

[Randy Holmes-Farley Verified Community Expert]

Anything that adds surfactants (such as soaps or detergents, whether natural or synthetic) to the water will cause excessive foaming.

 

[CubsFan]

Could be a clogged air intake.

 

[NMreef]

On my Nyos 120 skimmer, the plate that causes the bubbles to vortex is held in place by friction. Every few months the plate migrates up the post and detaches, causing the bubble to shoot straight up and overflow the cup. It is the first thing I check now.