Added carbon and GFO, now skimmer pulsing

I added a reactor running carbon and GFO about three weeks ago. Ever since my skimmer has been pulsing or intermittently pulling air. It's a Bubble Magnus NAC 3.5 on a 54g w/ 20 gallon sump. Before the addition of the filter media, the skimmer worked great...now it doesn't pull squat. I just replaced the atman ph1100 pump thinking the old pump was wearing out, but no luck. Same issue. This skimmer has been great to date, but I'm seriously considering switching it out with a reef octopus.

Any thoughts on cavitation as a cause. I tried cutting off some air intake, but this didn't work as the Venturi was still pulsing.

Any suggestions?

 

You are pulling out a lot of what the skimmer pulled with the carbon and GFO. I doubt anything is wrong with your skimmer.

 

I've been thinking the same thing. I thought that there weren't enough DOCs to get any foam going, but last night I dropped the skimmer level to a point where the suction is consistent and a large head of foam formed. The problem is that the foam formed too low in the skimmer to ever make it to the collection cup.

So, the questions I have are: 1) has anyone experienced intermittent venturi suction after adding carbon and gfo?; 2) if you did, did suction return after the carbon and gfo were used up?; 3) if not, has anyone experienced this before and, if so, what are some fixes I can look into?

Note that I can't place the skimmer in deeper water. The skimmer worked great before adding the gfo and carbon in the same depth of water. The problem is that I just can't figure out if the carbon/gfo is causing the problem or if the problem began to occur coincidentally around the same time I added the carbon/gfo...

Any input is appreciated. Thanks!

 

Most likely it is just the carbon competing with the skimmer. Carbon is more efficient at removing DOC than a skimmer, there is just no way around it. Lowering the water lever, you have more air per unit area of water, so, I think it makes sense that you will get more foam. You could try cleaning the skimmer, and run it in some vinegar water overnight. Also, check the manufactures water level recommendations. That can make a big difference, but if no change, I would say it's the GAC.

 

+1 on above

 

Right, that does make sense. But, why does lowering my water level make the Venturi pull air consistently? My other question is why is there a good head of foam when the Venturi is pulling consistently if there are not enough DOCs to remove?

 

Oh, and thanks for the input from you all. I really appreciate it.

 

Bump...

 

I'm not sure what you are describing. Do the bubbles shut off completely? Or does it just not pull any gunk. I'm not familiar with that skimmer, but some skimmers will not pull any air, if the water level gets higher than the intake. It is possible that you are raising the water level too high, possibly to attempt to compensate for the fact that the skimmer isn't pulling gunk because of the carbon

 

The bubbles don't shut off completely, it doesn't pull any gunk, and the air intake is well above the water level inside the skimmer.

1) I've had this particular tank running for 3 months.
2) the skimmer pulled tons of gunk.
3) I began to have GHA in a couple of places.
4) I added a dual reactor running high capacity GFO and carbon.
5) nothing regarding my skimmer changed.
6) skimmer stopped producing any waste.
7) I've gone through every piece of the skimmer and the pump to make sure nothing was wrong.
8) placed everything back as was thinking the GFO/carbon was the cause of the failure.
9) after two weeks, I discovered the air intake was intermittent and that there wasn't a constant pull or flow of air getting to the impeller.
10) I again removed everything to try and diagnose the problem. Nothing was found.
11) I thought maybe the pump was wearing out it getting too weak to pull enough air, so I ordered a new pump.
12) installed the new pump.
13) still have intermittent pulse or air pull from air intake (Venturi) - I can tell this because I can hear it and because the water level constantly rises and falls just a little. When it pulls air, it sinks, when it can't pull air, it rises just a little.
14) lower water level in skimmer, not the water level in which it sits, and constant suction returns.
15) Leave at constant suction level and a nice head of foam forms.
16) no DOCs are removed because the adjusted water level in the skimmer's body is too low to allow it to spill over into the collection cup or even get near it.
17) get confused because I've never had this problem before the addition of GFO/carbon but still get a good head of foam when there is constant suction...

Clear as mudd!