Too big of skimmer?

Is there a point where it's counterproductive to have a large skimmer? For example, my 30g tank with an additional 10g of water for the fuge/skimmer gives me a total of 40g. What's the largest skimmer I should get? Reef Octo has their smallest one rate for 100g--is that too much? The pump that comes with it does 250gph. Sitting in my sump that is turning over @ 120gph seems like overkill.

Thoughts?

 

I have the NWB-110 on my 30 gallon cube + 10 gallon sump system but I am running morel like 500GPM through my sump. It is also going to be an LPS/SPS dominant tank so I wanted the higher skimming capacity. I think you would be closer to "overkill" thank "underkill" but to say "counterproductive?" - not sure about that.

I guess you would just be recirculating cleaned water at that point - but there are skimmer which are called "recirculating" skimmers so that cannot be all that bad . . .

 

i have a 38 gal tank that has around 30 gals of actual water volume and im running a skimmer rated for 220 gals and it works fantastic. its a little big in the tank but it will be going in a 30 gal sump in the future.

 

Yes, your skimmer can be too big. Bigger skimmers do not pull more out, they just stop working until enough DOCs build up again to puke into the cup. Meanwhile you have a skimmer sitting there taking up more room than needed and using more power than needed which cost more that it needed to. It's arguable that bigger skimmers actually perform worse than skimmers properly rated to the task.

About as big as you can ask a skimmer to span is about twice rated. At those ends it will run not so great on the low end and not quite keep up on the high end. Perfectly acceptable though IF you KNOW you will be moving to a bigger tank soon. If it's just a hope then get the right one now sell it later and get the right one then.

You want to shoot for a skimmer around 125-150% of your system, that way you have a bit of head room should something crawl back in the rocks and die. Look at SWC 120 and 160 cones. Nice units for the smaller non nano tanks.

 

+1 to powerman. it wont pull more than whats there and is using more power than needed. i wouldnt have got one so large but ill be starting a larger build soon so it was future planning. i would however go 50% larger than recommended or even a little more because i feed more and whatnot. gives a little faster cleanup.

 

+2 to powerman. I have an octo 110 recirculating on my 29 and a 150 on my old 75. On the 75, it goes all the the time. On the 29, it goes for a while, stops, goes for a while, stops etc... Pulls out plenty of gunk though.

 

There is actually some talk out there form a "competing" method that suggests skimmers pull out too much food from the water column. Now I don't agree with that... however it does raise a good argument that too large of a skimmer pulls out food too fast and does not leave enough dwell time for corals to get their mits on it after feeding time.... of course the solution to that is when feeding coral food turn your skimmer off for a few hours, but that can be a hassle depending on oyur set up.

... not for this reason, but Idid have a controller and I would dose rotties or oyster eggs at bed time after lights out and I would put the skimmer on a 3 hour feed timers to give the corals time to soak it all up. I had some good growth.

 

Yeah, probably depends on the corals too. I think in practice, though, pulling out too much, or too quickly just dosn't seem to occur. Regardless of how oversized the skimmer is, there seems to be a limit to how much it can pull and it isn't nearly everything IMO. Some disagree though, such as Eric Borman, here in "Myth 17" here :Mything the Point, Part Three: Conclusion - Reefkeeping.com

He goes as far as to recomend using a very efficient skimmer, but shutting it off, for longer and longer durations, as long as water quality continues to be maintained. I don't agree with this though, this will significantly shorten the life of most pumps and IME, skimmers shut themselves off as Powerman and IMO, do not ever pull everything out due to physical limitation of the method.

 

What do you mean by "a skimmer does not pull out everything"?

A skimmer is a form of a mechanical filter... just by catching up stuff in the bubble column... but it isn't like a skimmer is an efficient mechanical filter. Some particulate can be removed though. What a skimmer removes is hydrphobic DOCs. Those that hate water and are actracted to air/water interface. They do not remove hydropholic DOCs and no body has ever claimed they do.

So along with the DOCs it can pull out particulate such as ditritus and even pods and larvea....all of which are food for other things. But the whole point of having efficient skimmers and fuges and biopellets and what not isn't so we can have crystal clear water.... it is so we can feed more more often with out that coresponding decrease in water quality and increase in nutrient levels that drive algae blooms that choke out corals.

There was a study done that showed that in the end one skimmer design was not any better than another, but there was a difference in the speed they cleaned. While I aslo don't agree with a lot of the studies finding, I can agree it's reasonable to say there is a difference in how quickly efficient skimmers can pull stuff out. So it seems resonable that too big of a skimmer would pull stuff out more quickly than is needed. It's just a guess though.

 

So if I feed every other day and have a pretty light bioload, a skimmer rated up to 100g is probably too much? I have a 30g with 10 extra gallons in the sump/fuge. Bubble magus has one rated for 65 which I thought about getting to.

For me it's a toss up between the smallest Bubble Magus and the smallest Reef Octo.