Is it possible to over skim?

[VincesReef]

Is this possible? I would think that a skimmer no matter how good can only pull out whats in the water that needs to be pulled out. once it pulls all the waste it would just be recirculating right?

 

[Waters]

Other than stripping the water of too many nutrients, you can't "over skim". Like you said, you can only take out what is in the water.

 

[Randy Holmes-Farley Verified Community Expert]

I think it is kind of an uncertain question without a single definitive answer.

You typically don't want to remove all organics, but skimmers probably can't anyway.

Is removing too much bacteria and/or other plankton undesirable? Maybe. It can take away from filter feeders.

 

[VincesReef]

I agree with both of you. You can only pull out what's there, which maybe all of the nutrients but in my mind I would think this would allow you to be almost exact on what nutrients are in the tank because you would have to add them. Say you went with a skimmer 5x or 10x over the volume of your tank. Like a External regal 250 on a 50 gallon tank. I know this isn't very cost effective or practical but just for the sake lets say you have an extra one laying around(Like I do) LOL. This in theory would strip the water clean and you could figure out a dosing system with bacteria and a filter feeder food source to maintain pristine water parameters.

Over thinking all this obviously but not sure if this has ever been something that's been tested. I've always heard over skimming is possible but have never heard any evidence to prove the point.

 

[Randy Holmes-Farley Verified Community Expert]

I agree with both of you. You can only pull out what's there, which maybe all of the nutrients but in my mind I would think this would allow you to be almost exact on what nutrients are in the tank because you would have to add them. Say you went with a skimmer 5x or 10x over the volume of your tank. Like a External regal 250 on a 50 gallon tank. I know this isn't very cost effective or practical but just for the sake lets say you have an extra one laying around(Like I do) LOL. This in theory would strip the water clean and you could figure out a dosing system with bacteria and a filter feeder food source to maintain pristine water parameters.

Over thinking all this obviously but not sure if this has ever been something that's been tested. I've always heard over skimming is possible but have never heard any evidence to prove the point.

Skimmers do not directly remove ANY inorganic nitrate or phosphate (well, except perhaps tiny amounts present in the interior water volume of a bacteria or other skimmed organism), so there's no way you will get to excessively low inorganic nutrients from skimming alone.

 

[Whipples]

That and skimmers only remove a percentage of what is in the water, so there is a soft limit in their capability as well.

 

[bellasdad0911]

If you skim wet ( liquid tan ) skim then your removing more beneficial nutrients and bacteria that your tank needs to keep its biological population going. Dark smelly skim-mate is what you want. I have sterilized my tank twice from over skimming and stripping away all the good nutrition and bacteria so the answer is yes in my opinion.

 

[Twisted_Blenny]

i can never seem to get my skimmer to do a dry skim it always seem to be wet (liquid tan) is there a way to make it dry?

 

[VincesReef]

Twiste_Blenny what skimmer are you running an what size tank? Also whats you're bio-load? I had to lower my water level 2" below the recommended to get my skimmer really dialed in and producing that dark smimmate.

 

[Randy Holmes-Farley Verified Community Expert]

If you skim wet ( liquid tan ) skim then your removing more beneficial nutrients and bacteria that your tank needs to keep its biological population going. Dark smelly skim-mate is what you want. I have sterilized my tank twice from over skimming and stripping away all the good nutrition and bacteria so the answer is yes in my opinion.

What evidence is there that wet skimming is "removing more beneficial nutrients and bacteria that your tank needs to keep its biological population going"?

I tend to think wet skimming works a bit better than dry skimming in terms of total organic matter exported, but your statement makes it sound like the effect is dramatic and makes it easy to overskim if skimming wet.

 

[VincesReef]

"removing more beneficial nutrients and bacteria that your tank needs to keep its biological population going would most likely happen. At that point I would think you could setup a dosing pump after figuring out how much organics to add back into the tank to keep the bacteria "fed". It would almost be like how we supplement corals with Calc, Mag, All, Etc...

I'm no expert by any means and the way I understand the nitrogen cycle is the bacteria breaks down organic waste so it's no longer toxic in the aquarium. If we are "over skimming" and removing all the organics from the water column then would we need the bacteria in the first place?

 

[TbyZ]

Is this possible? I would think that a skimmer no matter how good can only pull out whats in the water that needs to be pulled out. once it pulls all the waste it would just be recirculating right?

In regards to TOC you could run your skimmer 24/7 & never remove even 50% of tank TOC if feeding fish on a regular basis.
You should turn it off when feeding coral food like reefroids, because it will remove it as the food flows through the system, rather than being taken up by the corals.

Careful where you place the skimmer in the system hecause it will also suck up critters like copods.

Bacteria removal is another thing again as some bacteria is removed via skimming where as other bacteria are not, & Felding suggested this could be a problem.

 

[Reefbuds]

I agree with both of you. You can only pull out what's there, which maybe all of the nutrients but in my mind I would think this would allow you to be almost exact on what nutrients are in the tank because you would have to add them. Say you went with a skimmer 5x or 10x over the volume of your tank. Like a External regal 250 on a 50 gallon tank. I know this isn't very cost effective or practical but just for the sake lets say you have an extra one laying around(Like I do) LOL. This in theory would strip the water clean and you could figure out a dosing system with bacteria and a filter feeder food source to maintain pristine water parameters.

Over thinking all this obviously but not sure if this has ever been something that's been tested. I've always heard over skimming is possible but have never heard any evidence to prove the point.

I'll buy that 250 just laying around

 

[Mr. Brooks]

If you're having to constantly add nitrate to get to detectable levels then yes you are over skimming. I had two skimmers on my system and had to remove one. Corals need a certain amount of nitrate and phosphate. Gotta find the sweet spot.

 

[Randy Holmes-Farley Verified Community Expert]

I'm no expert by any means and the way I understand the nitrogen cycle is the bacteria breaks down organic waste so it's no longer toxic in the aquarium. If we are "over skimming" and removing all the organics from the water column then would we need the bacteria in the first place?

The "nitrogen cycle" that most people refer to is the conversion of ammonia (toxic) to nitrite to nitrate (low toxicity). All of these are inorganic chemicals and are not directly skimmable, and the bacteria that drive this process do not require organic chemicals in the water to do it.

Ammonia is released by fish and other organisms when they metabolize foods that contain nitrogen (most of which are organic compounds, such as proteins), so there's no way around creating ammonia, whether you skim or not, if you feed the fish.

Consequently, all reef aquaria need something to take up the ammonia. I'm not certain whether nitrifying bacteria (those that convert ammonia to nitrite to nitrate) are ultimately needed in every reef tank, since other organisms such as macroalgae and corals may actually be the primary consumer of ammonia, but they are certainly needed in the early stages of any reef aquarium, and may still be important in them later to ensure ammonia does not rise too much.

 

[Randy Holmes-Farley Verified Community Expert]

If you're having to constantly add nitrate to get to detectable levels then yes you are over skimming. I had two skimmers on my system and had to remove one. Corals need a certain amount of nitrate and phosphate. Gotta find the sweet spot.

I can't see how that follows. Even a nonskimmed tank can have nitrate too low. It's just a matter of too much expert relative to import, and there are many reasons to skim that do not relate to nutrients.

 

[MrWheelock]

I like to think that I skim only to remove large particulates from the water column such as floating detritus, excess fish poop etc. I don't skim to lower Nitrites, nitrates, or ammonia. I have live rock, live sand, and macros that house bacteria or consume those. Unless I'm not understanding this whole bacteria cycle.

 

[Mr. Brooks]

I can't see how that follows. Even a nonskimmed tank can have nitrate too low. It's just a matter of too much expert relative to import, and there are many reasons to skim that do not relate to nutrients.

"It's just a matter of too much expert relative to import"

Exactly, If you're exporting too much relative to import, then I believe you are over-skimming.

 

[Twisted_Blenny]

Twiste_Blenny what skimmer are you running an what size tank? Also whats you're bio-load? I had to lower my water level 2" below the recommended to get my skimmer really dialed in and producing that dark smimmate.

75g running a bubble magus curve 5. bio load 2 cinnamon clowns, lemon peel angel, six line wrasse and a green chromis. of course the clean up crew snails, crabs. i might have to lower the level and see what happens

 

[Randy Holmes-Farley Verified Community Expert]

"It's just a matter of too much expert relative to import"

Exactly, If you're exporting too much relative to import, then I believe you are over-skimming.

lol

I meant other exports. Denitrification, organism uptake, etc.

I do not think people with too low of nitrate have that because they are skimming too much.