Over Skimming - Is it Real

[redfishbluefish]

I hear folks commenting on some posts about the dangers of over skimming. Is there truly any such thing? When I first set up my 90, I ran an MRC 2, that I upgraded to an MRC 3. I can't remember the ratings for these skimmers, but they were beasts for much larger tanks. I never had any issue!...and by the way, the best skimmers I ever ran as far as pulling out schmutz. My feeling is that if the schmutz is no longer there, nothing will get pulled out. But since the schmutz is constantly being produced by fish and corals, the larger skimmers pull it out quicker. I always still had my N's and P's, so that was never an issue on that end.

So any real stories where over skimming (too large a skimmer), was an issue in your tank?

 

[twilliard]

Good one Paul! I know my helix 5000 is oversized for my volume. Makes me question the removal of too much bacteria

 

[redfishbluefish]

Bacteria really doesn't hang out in your water column. You certainly find some in the water column, but that's just temporary, while they're in the process of going to visit relatives. Otherwise, the majority of bacteria is in your rocks and sand.

 

[twilliard]

When I look at it under the microscope all I see is algae clusters. It it interesting and I am not a believer of over skimming.
We need more input from people :)

 

[dragon99]

Since a skimmer can only pull ~30% of the organics out of the water I don't see how it's possible to over skim. The problem will likely be that the skimmer won't consistently create a stable foam if it's significantly oversized.

http://www.advancedaquarist.com/2010/1/aafeature
None of the skimmers tested removed more than 35% of the extant TOC, leading to the conclusion that bubbles are really not a very effective medium for organic nutrient removal.

 

[redfishbluefish]

When I look at it under the microscope all I see is algae clusters. It it interesting and I am not a believer of over skimming.
We need more input from people :)

Just to clarify, "I am not a believer of over skimming," does that mean:

A. Over skimming should never be done.....period!
B. Over skimming can't hurt anything....go for it!

 

[twilliard]

Just to clarify, "I am not a believer of over skimming," does that mean:

A. Over skimming should never be done.....period!
B. Over skimming can't hurt anything....go for it!

Sorry I stated that wrong Paul.
B- is my answer

 

[JMLewis]

Absolutely real, but very tank dependant imo.

My theory is...Back in the day most of us packed our tanks with tons of live rock giving detritus tons of dead spots to settle and rot. In that case the biggest skimmer we could fit in our sump was appropriate and necessary to keep our nutrients manageable.

However more and more you see very open and minimal aquascapes and people not overstocking their tanks with fish. In this case (and in my case) too large of a skimmer keeps the nutrients too low for coral to thrive and/or even survive. I scratched my head for months wondering why my corals were looking very bad. My thinking was "ALK, CA, MG are perfect. Po4 and no3 almost undetectable everything should be triving!! What the heck is going on!?!?"

We'll basically I was starving my corals to death. Zooxanthellae are at the end of the day an algae and need nutrients to survive and if your stripping your tank of any and all nutrients the zooxanthellae slowly die without any "food".

I run a Vertex Omega 150 on a 66g tank because I purchased it with the thought "get the biggest skimmer you can fit". Well now that it's been off for a month and I started dosing nitrates my corals have slowly started to make a come back, but unfortunately I didn't realize what I was doing wrong until it was to late for a large portion of them.

 

[Paul B]

In my opinion I doubt you can overskim. My skimmer is huge and has been running 24/7 for over 40 years with ozone, no problems yet

 

[nervousmonkey]

I'd love to see your Helix 5000 Todd, sounds like a cool machine! I am not a big believer in over skimming either, though I do believe that most companies over rate their skimmers by some margin. I run a Deltec rated for 285 gallons on a Red Sea 135 gallon tank, with plans to add other tanks to the system. However, currently there isn't anything but the 135 gallon and the Deltec skims away a bunch of schmutz.
My definition of over skimming is that the skimmer cannot function properly in a saltwater environment, due to a variety of reasons:
1. The skimmer is so "yuge" that it has an internal volume many times greater than the tank itself, so it cannot produce any skimmate because the water is just too clean since it is so enormously oversized (I think I can argue myself out of this one though... Every once in a while the "nano" tank would produce enough schmuck that I would think that the SuperSkimmer would collect something miniscule on one of its' super powered, mighty bubbles...)
2. The skimmer can clean the entire tank with only a few of it's bubbles, making it appear that there is nothing in the collection cup because the skimmate is so dry that it literally turns to dust and just gets blown away by the slightest breeze such as a cooling fan for the LED's.
3. The skimmer is so good that it only needs to be turned on for a minute or two every 24 hours or so to perfectly cleanse the water column, and any time outside this defined time is "wasted time".
4. The skimmer cannot produce any skimmate at all because it is so good at what it does that it considers the schmuck that passes through it to be beneath its' foam fractionating capabilities.
5. The skimmer is just so good that it skims 100% of all DOC's, nitrates, phosphates, sulfates, dead fish skin cells, all chemical structures and even the extra milk fat off the top of the skimmer. The skimmer ends up firing itself because it is so good that it can convert a saltwater tank into a freshwater tank with its' ability to pull all non H2O related "stuff" out of the water column.
With those definitions in mind, I would think that the only way that you could truly "overskim" would be to purposefully not allow the bubbles to rise high enough to reach the collection cup, but that would be a deliberately stupid decision.
So my $0.02 on over skimming.

 

[nervousmonkey]

In my opinion I doubt you can overskim. My skimmer is huge and has been running 24/7 for over 40 years with ozone, no problems yet

True? As in reality here and not a funny Paul B joke? 40 years AND with ozone running 24/7 on top of it? If this is the case, then I think the thread has just been closed and a definitive answer found... :confused::confused::confused:

 

[twilliard]

Ohh ya baby!

 

[Paul B]

True? As in reality here and not a funny Paul B joke? 40 years AND with ozone running 24/7 on top of it? If this is the case, then I think the thread has just been closed and a definitive answer found... :confused::confused::confused:

Yes it is true. I started using ozone a few years after I set up my tank. Ozonizers have gotten much better now but I never ran my tank without one.

My very sexy DIY skimmer and you can see the ozonizer on the wall near my very cool thermostat gage that I took off one of the boilers in the Plaza Hotel in Manhattan.
Don't make fun of my phone. It is an I Phone, the cord is just so no one steals it.

 

[Randy Holmes-Farley Verified Community Expert]

I remember posing this exact question in the Compuserve Fishnet days. lol

I suspect some "results" have confounded excessively low nutrients with overskimming.

 

[nervousmonkey]

Ohh ya baby!

WHOA! That thing is a monster Todd! It looks like it could skim Tampa Bay clean... o_O Nasty ol' Tampa Bay is disgusting, but that thing looks cooler than it sounds! Does it really spin the water up along with the bubbles with the two impellers on top and bottom of the bubble plate?

 

[twilliard]

WHOA! That thing is a monster Todd! It looks like it could skim Tampa Bay clean... o_O Nasty ol' Tampa Bay is disgusting, but that thing looks cooler than it sounds! Does it really spin the water up along with the bubbles with the two impellers on top and bottom of the bubble plate?

Yes it does, I feel that the impeller is a major player with this skimmer.
Orphek nailed this one and I have one heck of a "bone-yard" of skimmers
You would have to see one in person ;)

 

[nervousmonkey]

Yes it is true. I started using ozone a few years after I set up my tank. Ozonizers have gotten much better now but I never ran my tank without one.

My very sexy DIY skimmer and you can see the ozonizer on the wall near my very cool thermostat gage that I took off one of the boilers in the Plaza Hotel in Manhattan.
Don't make fun of my phone. It is an I Phone, the cord is just so no one steals it.

That is pretty cool Paul. How did you learn enough about foam fractionation to build that? I hope the answer involves something with a crowbar, dead raccoon, majano wand, three Supermodels with a flounder, and if you can somehow pull Amelia Earhart into the story, I'd be incredulous. :eek:
That's not a dare Paul, I'm just playing around, but amazing you did that 40 years ago. What's the maintenance like on that thing? And you just run ozone constantly? No ORP measurements of course, but probably enough contact time in that tower to allow ozone to break down anyway.
Interesting.

 

[Paul B]

Orp measurements! Really! I run that sucker as high as it can go and I don't use no Sissy, Girly Man carbon. Foam fractionating has been around for treating sewage for quite a while. I built my first ozonizer from a neon transformer but the thing made a lot of noise and dimmed the lights in the neighborhood so the Supermodels had trouble putting on their make up. I also did keep flounders in the tank then as it was hard to get tropical fish and the only stuff available was damsels. Only small flounders and I released them when they got big. I know you are not supposed to do that. Shoot me.
There is almost no maintenance on it as I don't remember ever taking it apart and If I remember correctly Amelia Earhart may have helped me put it together. It has been hanging on there as long as I can remember and I can't remember to far back since I got hit in the head with that cro bar while I was chasing that raccoon away from my garbage cans.
I only have to remove the tube at the top occasionally and clean it. The thing dumps into a five gallon bucket that has a shut off switch on it in case it fills it shuts off the 2 pumps that run it.

 

[nervousmonkey]

HAHA! Now I am pretty unsure that I know what is the truth and what isn't Paul. :cool:
Kidding about that one man, great story. Made me laugh that you actually came up with that, even made me show to some non-reefing friends from work in LA. They cracked up too.
Thanks Paul!

 

[NanaReefer]

I run an IceCap K2-120 on my 40B/20L sump. It's rated for tanks from 75-120g. I also run a sock. I've got 3 fish, bunch of corals.
I was always a stickler for not over feeding. I don't concern myself with that anymore. This skimmer allows me to feed both fish food & coral foods specific without worry.
No I don't believe in over skimming. It can be compensated for.