Protein Skimmers

[bladeruner143]

Hey guys,

I was doing some research into protein skimmers and I came upon something that I didn't know the answer to. What is a "recirc" skimmer? i know this is a noob question, but one that I think need s to be asked in order for me to figure out some skimmer questions that I have. Thanks guys!

 

[shiveley]

Recirculating Skimmer Designs

A recent trend is to change the method by which the skimmer is fed 'dirty' water from the aquarium as a means to recirculate water within the skimmer multiple times before it is returned to the sump or the aquarium. Aspirating pump skimmers are the most popular type of skimmer to use recirculating designs although other types of skimmers, such as Beckett skimmers are also available in recirculating versions. While there is a popular belief among some aquarist that this recirculation increases the dwell or contact time of the generated air bubbles within the skimmer there is no authoritative evidence that this is true. Each time water is recirculated within the skimmer any air bubbles in that water sample are destroyed and new bubbles are generated by the recirculating pump venturi apparatus so the air-water contact time begins again for these newly created bubbles. In non-recirculating skimmer designs, a skimmer has one inlet supplied by a pump that pulls water in from the aquarium and injects it with air into the skimmer and releasing the foam or air/water mix into the reaction chamber. With a recirculating design, the one inlet is usually driven by a separate feed pump, or in some cases may be gravity fed, to receive the dirty water to process, while the pump providing the foam or air/water mix into the reaction chamber is set up separately in a closed loop on the side of the skimmer. The recirculating pump pulls water out of the skimmer and injects air to generate the foam or air/water mix before returning it to the skimmer reaction chamber -- thus 'recirculating' it. The feed pump in a recirculating design typically injects a smaller amount of dirty water than co/counter-current designs. The separate feed pump allows easy control of the rate of water exchange through the skimmer and for many aquarists this is one of the important attractions of recirculating skimmer designs.

 

[shiveley]

Here's an image to help you visualize the concept:

 

[bladeruner143]

Thanks Shiv, that helped out a lot! Now, a follow up question and this may start some kind of philosophical debate, but I think I also need to ask this, are they worth the extra money? Do they actually skim better than a non-recirc skimmer? I know theres no "proof" but I just want to hear your opinions. I've been looking at the sub $200 skimmers for a 90G total system (I'm really liking the Octopus 110 and was trying to decide between the recirc $200 and the needle wheel $160)

 

[shiveley]

for some skimmers, like ASM's for example, recirc mods can make all the difference in the world. I don't know much about Octopus skimmers, but I like what I've seen so far in relation to the efficacy of recirculating models in general. And I may be in the minority here, but I'm still not all that impressed by needle-wheel skimmers...

 

[jtarmitage]

Simple difference between a recirc and a non recirc is # of pumps needed to operate. The non recirc will use a single pump to both feed and aspirate, while a recirc will split the duties between 2 pumps. The benefit of a recirc is that the head pressure is removed aspirating pump, increasing the volume of air injected into the skimmer body. If a non-recirc skimmer wanted to use the same amount of air as a recirc, any increase in air would also increase volume of water injected, causing turbulence inside the skimmer(which is bad).
Simple answer to your dilema, the extra $40 is well worth it. For a much larger price differential, it would be more of an issue to debate.

 

[kdblove_99]

I have had both and defiently like the recirc. More dwell time in a recirc.

if Jimdogg187 gets one here he knows alot about this

 

[Jim_S]

I'd say the cost increase of an external pinwheel skimmer usually doesn't equal performance gained. Its a shame that skimmer companies charge so much for such minor alterations.

But, I will say that is does add: flexibility to drain feed, run externally, draw more air and slow down dwell time, and not affected by sump water level fluctuations. If you value these, then RC is the way to go. I prefer to run my skimmer externally and drain fed, so this is how I went.

When you drain feed, your skimmer gets raw surface water directly from the overflow. According to studies, this is the most nutrient rich water because proteins float to the top. Its a little more efficient in this matter, but there is no real way to test to conclude how much.

Either insump or external will work fine. Pick one that fits your budget/goals and you'll be fine.

HTH

Jim