Multiple skimmers - why/why not?

[Larry Grenier]

People get bigger tanks and then sell their old skimmer, which may be great for a smaller system, to get a new, larger capacity skimmer.

 

Why don't folks add a 2nd skimmer? OK, more to clean but alternating cleaning each has advantages too. Does one somehow defeat the other?

Edited April 17, 2009 by Larry Grenier

[extreme_tooth_decay]

I had 2 for a while. More redundancy in case 1 fails IMO.

[cordonbleu]

Multiple skimmers take up more space, draw more $$ on electric bill, noisier (I guess)

Edited April 17, 2009 by cordonbleu

[ctenophore]

I agree, two smaller skimmers are probably equal or more efficient than one big one, especially if they are run in series. But, few want the maintenance associated with two skimmers, and everyone loves to justify a new, big toy for their tank.

[treesprite]

everyone loves to justify a new, big toy for their tank.

Perfect answer

[L8 2 RISE]

It can lead to excess oxygen in the tank... = excess oxygen

[treesprite]

What happens if there is excess oxygen?

[L8 2 RISE]

What happens if there is excess oxygen?

 

Nuisance algae's mainly... I don't know if anything bad can happen to your corals, etc if there is though...

[ctenophore]

Nuisance algae's mainly... I don't know if anything bad can happen to your corals, etc if there is though...

Algae use CO2, not O2. If anything, better gas exchange from multiple skimmers (which is unlikely anyway) would make corals and fish happier, provided the gas being exchanged is "normal" concentrations of CO2, O2, etc.

[extreme_tooth_decay]

I think we're getting off track.

 

As I understand the premise of this thread, it is "2 small skimmers vs 1 big skimmer". So, the idea is that the 2 small skimmers equal the large skimmer. So, there would be the same gas exchange, O2, etc.

[CHUBAKAH]

I think we're getting off track.

 

As I understand the premise of this thread, it is "2 small skimmers vs 1 big skimmer". So, the idea is that the 2 small skimmers equal the large skimmer. So, there would be the same gas exchange, O2, etc.

They say great minds think alike. I was just going to post that.

 

I will have two skimmers running in a few weeks.

[L8 2 RISE]

Algae use CO2, not O2. If anything, better gas exchange from multiple skimmers (which is unlikely anyway) would make corals and fish happier, provided the gas being exchanged is "normal" concentrations of CO2, O2, etc.

 

I'm not arguing with you on this, but I asked this exact question on another forum as well as spoke to an LFS owner around here a little while ago, and both said that multiple skimmers causes excess oxygen, and causes nuisance algaes. Also, the chemicals that are used to control cyano, for example, do so by lowering oxygen levels because that's what cyano thrives on. At least this is what I've read theses chemicals do, however I may very easily be wrong... I'm just trying to clarify.

[Larry Grenier]

I'm just trying to understand if there is a downside of using 2 skimmers besides the maintenance issue.

 

Also, I've always understood that marine aquarium algae thrives in low oxygen and high nutrient environments; two things that "overskimming" would fight.

[Coral Hind]

I agree with Ctenophore, if the air intake to the skimmer is "normal" there would not be any dangerous levels of O2. Just as the skimmer helps to balance the CO2 levels it would also balance an excess of O2.

 

The extra skimmer might increase the tank's evaporation rate a little.

Edited April 17, 2009 by Coral Hind

[flowerseller]

I did not know you could get too much oxygen into water. I thought saturated oxygen levels ment you could not get more in and the rest just dispursed.

I understand cyano to come from lowered oxygen levels in conjuction with low/poor light spectrum. This is often caused by "dirty" water which having one big or 2 medium skimmers would likely prevent.

 

I've run two skimmers before and one often shuts down production or causes the other to produce less skimmate.

I understand redundancy but why fiddle with keeping two skimmers producing?

[Origami]

At the very most, a second skimmer will saturate the aqueous gas content in accordance with the ambient atmosphere (or air source for the skimmers). It will not lead to concentration in excess of what would constitute equilibrium.

 

A second skimmer, if significantly different than the first might either effectively shut down or be shut down by the one performing at a higher level. At some point, the less efficient skimmer will be incapable of generating enough foam to carry pollutants up through the riser.

 

Here's another aspect to the problem: There are also some people who believe that the composition of skimmate varies depending upon skimmer design. In this case, a second skimmer might actually lead to a more complete removal of pollutants. I'm not sure if I subscribe to this line of thinking, though, and mention it just because I've read it somewhere.

[lanman]

If you had plenty of space... and two people were selling skimmers that could handle 200 gallons of tank each for $150 each. And the skimmer that could handle 400 gallons of tank was $700 - I think I'd give it a try!

 

bob

[overklok]

I had this exact scenario on one of my systems. I had a tunze 9002, pulling good scum. After I put in a deltec mce 300, the tunze would not pull any skimmate. The tunze became useless.

[treesprite]

I bought Sara's ASM last week so I am using 2 skimmers now for my 65.

 

Does a skimmer usually automatically "win out" over the second if it is rated for higher gallons than the second (that is, is thee is any winning out to be had)?

[Origami]

I bought Sara's ASM last week so I am using 2 skimmers now for my 65.

 

Does a skimmer usually automatically "win out" over the second if it is rated for higher gallons than the second (that is, is thee is any winning out to be had)?

 

Ah, Forrest, but that's the question! We'll be waiting for another data point from you.... (What exactly are the two skimmers that you've now brought online? Post a picture of how you've got them staged as well - side by side vice series.)

[extreme_tooth_decay]

I understand redundancy but why fiddle with keeping two skimmers producing?

 

When I did it, I used a G3 and a Remora Pro, and my total "fiddling" went from "less than 5 minutes per week" to "less than 5 minutes per week".

 

And, neither of them "shut down".

 

It seems to me that given how slowly skimmers work (for me), the idea that one of them could pull everything out so fast that the other would not do anything seems unlikely. Maybe I have just had sluggish skimmers. I am a tightwad after all.

 

tim

[Larry Grenier]

Bob's response was one along my line of thinking

...if two people were selling skimmers that could handle 200 gallons of tank each for $150 each. And the skimmer that could handle 400 gallons of tank was $700...

 

My sump is in the basement and I don't care about noise. My next upgrade will be to replace my hodge-podge little fuge & frag tanks with 1 big one and add a 2nd skimmer rather than take a loss on the one I already own which works fine.

 

The new toy syndrome is admitedly valid too :-)