[Bonneville08]

Can we over use protein skimming? I’ve seen this question a lot in my short time on aquarium web sites. The purpose of this thread is to provide information for each aquarist to make his own decision based on commonly accepted principles. Those folks who know me are aware that I get irritated by folks whom I would like to refer to as “Uberskimmers”.
I have read and use the following books as references for this thread:
•“The Marine Aquarium Handbook” by Martin Moe
•“Giant Clams” by Daniel Knop
•“Protein Skimming & Activated Carbon Secrets” by Bob Goemans
•“The Reef Aquarium” by J. Charles Delbeek and Julian Sprung
Lets start out by presuming that this a moot question for FOWLR aquariums, as the detrimental aspects of protein skimming either have a minimal effect or are compensated for by the amount of nutrient/trace element import.
My personal goal is to provide an environment for my animals that replicates natural conditions to the best of my ability and to mitigate the effects of the limitations of a home aquarium such as limited volume, lack of bio-diversity, and inherent lack of stability.
2/3 of pollutants in the aquarium start out as surface active. Given this, I would agree that protein skimming is beneficial to any nutrient control method. There are most certainly measures that can be taken to replace protein skimming under tightly controlled conditions, but this is an entirely different topic.
Protein skimming does remove some trace elements. Which elements and how much of each is debatable, however, it is widely accepted that Iodine and Iron are both depleted by protein skimming. 202 mg/g Calcium, 21.2 mg/g Magnesium, 5.63 mg/g Phosphate, and 30.3 micrograms/g Iron have been measured via spectrometer in dried skimmate (Mizuno).
Protein skimming clarifies the aquarium water. This has the effect of increasing the light and energy available to our photosynthetic corals.
Protein skimming increases gas exchange in the water column. This has the effect of increasing oxygen levels and stabilizing pH by decreasing CO2 levels in the aquarium.
Protein skimming can have a detrimental effect on plankton population. It is widely accepted that phytoplankton is removed by protein skimming; this has the effect of limiting the zooplankton population and thereby reducing a viable food source to our invertebrates. This severely limits the food chains that can be formed using a more natural method of filtration.
Protein skimming can reduce the levels of dissolved metabolites from plants and animals. This reduces the chances of corals suffering from turpenoids emitted from other corals as well as emissions from different species of algae.
The ratings that manufacturers assign to protein skimmers can be inaccurate. One of the cornerstones of skimmer efficiency is water flow rate; you should expect the flow capacity of the skimmer to turn over your total system volume several times an hour. 5 to 10 times per hour is not uncommon.
Higher air flow in a skimmer may not increase skimmer efficiency. Although the volume of air is important, the size of the bubbles and therefore surface area is critical to skimmer efficiency. The column of bubbles requires a certain level of stability to prevent collapse of DOC laden bubbles and return of DOC to the water column.
Cycling pumps on and off is one of the biggest contributors to premature failure. In order to maximize the useable life of the pump, it would be beneficial to minimize stops and starts.
Given the pros and cons associated with skimming, I would advise choosing a skimmer rated at or slightly above the capacity of your system and run it continuously. Choose the most reputable skimmer that you can afford. Monitor the water conditions and health of your livestock. Supplement trace elements in the aquarium and feed quality foods only in the quantities necessary to keep your animals thriving.
As in all things about our hobby, please question the advice you receive. Do you remember how well “because” worked with your parents when you got caught with your hand in the cookie jar? It shouldn’t work any better now.
Good luck and happy reefing,
Russ

[e_baer]

Excellent work! This is going to become a sticky!

[Bonneville08]

Thanks Elliot,
I'm glad you like it. I hope it helps, I spent the whole morning researching and writing it.

[michael]

what can i say russ, nice work

[Ganrin]

Nice work Russ.

"Protein skimming can have a detrimental effect on plankton population. It is widely accepted that phytoplankton is removed by protein skimming; this has the effect of limiting the zooplankton population and thereby reducing a viable food source to our invertebrates. This severely limits the food chains that can be formed using a more natural method of filtration."

That is probably the only negative to skimming that would make me consider not having a skimmer.

[Bonneville08]

Thanks Ganrin,
Just to clarify, I do not advocate giving up protein skimming unless you have other mechanisms or maintenance practices to take its place. I would like folks to consider how aggressively they skim given both positive and negative aspects of this tool.
Russ

[REEFMASTER]

I sometimes wonder about these skimmerless tanks?
With this info in hand, can we run our systems w/out it? I for 1 do not enourage a skimmerless reef tank, but as Bonneville mention in one of the paragraphs<Protein skimming can have a detrimental effect on plankton population. It is widely accepted that phytoplankton is removed by protein skimming; this has the effect of limiting the zooplankton population and thereby reducing a viable food source to our invertebrates. This severely limits the food chains that can be formed using a more natural method of filtration.>,.
I have this conversation over and over with a friend of mine that WORKS in a fish store and does MAINTANENCE work on the side. He has a couple of clients that does NOT have skimmers on their tanks! One of them I have seen with my own 4 eyes! I tested the waters just to see for myself,nad this is a THRIVING REEF TANK! w/ stonies and softies.
I feed my tank all sorts of phyto, and to run my tank w/out a skimmer would be a death sentence in my mind. I have copepods and all sorts of filter feeders so, when I do feed phyto, I shut my skimmer off at night, most corals open up at nite to feed any way, so there is no skimmer to compete with.
I had to comment on just that 1 paragraph, and Bonneville, good journalist work there!

[Bonneville08]

Hi Anthony,
I think most successful skimmerless tanks are due to one of two factors:
1. Lots of plant life, the export of macroalgae during a harvest can make a huge difference in nutrient export. No matter how nasty your skimmate is, you have to consider dry weight of import versus dry weight of export. Even wet weight, macroalgae harvesting is an extremely efficient way to export nutrient. IMO the species of plants may necessitate the use of skimming to remove algal byproducts.
2. Live rock or live sand can provide de-nitrification on a huge scale even without a skimmer. If the available surface area of rock and sand is much larger in proportion than what is necessary for livestock and therefore nutrient import, the short cut of skimming prior to the nitrification cycle could be avoided. This, of course, does not explain Phosphate control IMO, and would be curious how that is being taken care of.
A third way could be with ion exchange resins, although useful, they throw the whole argument of skimming on its ear.
Thanks for posting,
Russ

[Okayamapiper]

As for phosphate control, would not an elevated calcium level be a possible solution? Calcium will bond to phosphate, making calcium phospate, which is insoluble in water. Dosing Kalkwasser not only increases calcium levels, but removes the phosphate ion. Another method would be the use of aluminum oxide as aluminum oxide will bond with phosphate, making aluminum phosphate.

Overskimming certainly removes some good stuff as well as the bad. I wonder if anyone has tried a reef tank without a skimmer, using solely an ozone unit to oxidize DOC and a sulfur denitrator/calcium reactor to reduce the nitrates to nitrogen gas and supply calcium and trace elements from the denitrator effluent.

[jimw369]

If that is true James how come people that keep Ca levels at 450-500 which technically is considered an unnatural saturated solution still get Cyano growing in there tank? I was under the impression phosphates are needed for cyano to get started.

[Okayamapiper]

Cyano uses phosphates, nitrate and DOC (dissolved organice compounds) as food. Calcium will bond to free phosphate ions, but won't bond to larger molecules that you would find in DOCs, so until the oxidizing bacteria break down the larger DOC molecules into the phosphate ion, calcium is not effective and cyano is free to consume them.

[Bonneville08]

I was under the impression that Calcium Phosphate was soluble with a pH low enough to dissolve it. Given the precipitation is likely to happen on substrate of some form, is it likely that the acidic secretions of some bacteria may lower the pH locally at the substrate and make the Phosphate available again in trace amounts?
I've read this in an argument as to why Kalkwasser dosing should not really be considered a Phosphate export mechanism.
Just throwing this out as a point of discussion, as I do not use Kalkwasser. Thanks for posting guys.
Russ

[Okayamapiper]

Great point. Acidic secretion from bacteria could reverse the reaction and release the phosphate into solution, but as long as the calcium concentration remains high, it will precipitate out again. The acidic secretions arel not only neutralized by reacting with calcium phosphate, but by any other buffering material in the tank such as the substrate the bacteria lives in. As the amount of calcium phosphate would be much less than the buffering substrate, would not the bulk of the acid be consumed by the buffer?

[Bonneville08]

Originally Posted by Okayamapiper

Great point. Acidic secretion from bacteria could reverse the reaction and release the phosphate into solution, but as long as the calcium concentration remains high, it will precipitate out again. The acidic secretions arel not only neutralized by reacting with calcium phosphate, but by any other buffering material in the tank such as the substrate the bacteria lives in. As the amount of calcium phosphate would be much less than the buffering substrate, would not the bulk of the acid be consumed by the buffer?

I guess to answer the question definitively, we would have to know if the pH to make Calcium Carbonate soluble is higher than the pH for Calcium Phosphate.
But how else could someone have no measureable Phosphate in the bulk water and still get localized Phosphate driven algae blooms on substrate and rocks?

[Okayamapiper]

Possibly from another source of phosphate? The calcium ion binds to phosphate ions in the water, but phosphate is available to cyano in the form of DOC which calcium may not be able to bind to. Cyano uses DOC as well as nitrate and phosphate ions for building blocks.