Is two better than one? Is a recirculating protein skimmer extra cost worth it? | BRStv Investigates


– Today on BRS TV Investigates, we’ll find out if there’s an added benefit to using a recirculating
skimmer with two pumps over a more common single
pump skimmer design as well as how they compare to each other in performance terms
of air draw, stability, and ease of tuning in order to determine if the juice from the
recirculating skimmers independent pump design
is worth the squeeze. (upbeat music) – Hi, I’m Randy with this Friday’s BRS TV Investigates where
we put popular reefing gear theories and methods to the test by experimenting on our own tanks so you don’t have to experiment on yours and in today’s experiment, we’re putting recirculating skimmers to the test by pitting two
different skimmer designs with the same VarioS four DC skimmer pump against each other to see
which has the higher air draw, how that air draw’s
effected by water depth, and which one’s easier to tune. The numbers on this test
will probably surprise you as we try to answer the question, is a recirculating skimmer more stable and easier to tune than
a single pump skimmer? Before we get started in today’s data, lets quickly refresh ourselves as to the difference between
a single pump skimmer like the Reef Octopus Regal 200-INT and a recirculating skimmer
like the Regal 200EXT by looking at the
commonly believed benefits and challenges for each one. So what is a single pump skimmer? Obviously, these types of skimmers have one pump but it’s the mechanics of what that single pump
is trying to accomplish that really distinguishes them
from recirculating skimmers. That single pump feeds both
water and air simultaneously into the skimmer body
meaning that it’s in charge of producing the bubble
reaction or air draw, as well as the contact
time or how much water flows through the skimmer per hour. One of the benefits of
having a single pump pulling double duty is
that they’re typically a smaller form factor that saves space inside your sump and
even more space saving when manufacturers place the pump inside the skimmer body itself. Along with having a smaller
footprint and a single pump, in most cases, also that
means that manufactures can keep production costs down which can ultimately
make them more affordable and easier on your wallet. However there are some challenges that come with a single pump skimmer in that there is far less control over making individual adjustments to just the air or just the water flow, since the two are tied directly together from one pump doing both the work. Tied to that is that both variables for air and water flow are also effected by sump water level, meaning
that almost any change to one of these three variables, air flow, water flow, or skimmer depth, will impact multiple
elements at the same time which can turn the task of properly tuning a single pump skimmer into a game of performance whack-a-mole
or a juggling event where tweaks to any one of them ultimately effects the others. On the flip side of skimmer design, our recirculating
skimmers with the duty of drawing in air and bringing
water into the body, is split between two different pumps. First of all, the recirculating
pump does exactly that, it recirculates an air and water mixture inside the skimmer body to create foam. This skimmer feed pump is in charge of contact time and how much tank water is processed per hour,
recirculating skimmers can be both used internally and externally in most cases with the same benefits. Independent pumps means
independent controls. Second benefit is the
ability to control the air without effecting water
flow through the skimmer so a bit more or a bit less
air is adjusted by you. The skimmer is essentially a foam engine and ideal engine
performance can be achieved when the right ratio of
organics from the feed pump and air from the recirculating
pump is also achieved. Similar to a cars combustion engine, you don’t get more horsepower
when adding more fuel or oxygen individually,
you get better performance when you add more of
each in the right ratios. Either way, you can tune
it to your own system and feeding habits or bioload with all of these levels of control, the recirculating skimmer
is the more tunable design where you have full
control over the air flow, water flow, contact
time, system volume ratio and water height which all can be adjusted with almost no effect on each other. In some ways we can think
of a single pump skimmer as being similar to a carbureted engine that is simpler but easier to flood, whereas a recirculating
design is similar to a highly tunable fuel injected system that can optimized to nearly any available amount of fuel or in our case, fish waste, uneaten food, and organics. All right so that’s at least the theory behind the two skimmer
designs and how they operate, so lets put it to the test in two phases. In the first phase today
we’ll put the Regal 200INT and Regal 200EXT both with a
VarioS four DC skimmer pump to the test in five, six,
up to 11 inches of water to see how the air draw in each is effected by sump water level. Along with that I will
also cycle the DC pumps through its five different settings to see how the air draw
changes with pump speed. Next week in phase two of this test, we plan to set up three
different test tanks with skimmers set to
three different air flows and start dosing actual
organics for a better look at how different amounts
of air draw inside the body effect the performance which is the heart of this conversation. Getting into the results
for today’s testing in phase one of our experiments on skimmer design performance, lets first take a look
at how operating depth effects the air draw rate for both the Regal 200 INT and the Regal 200 EXT which both again, use that
VarioS four DC skimmer pump. Like we’ve done in previous tests, we place the 200INT and 200EXT in five, six, seven, and
up to 11 inches of water and measure the air draw at each level. Starting with the 200INT
which is a single pump skimmer design we see
that from five inches to 11 inches the air draw performance is absolutely effected
where there’s a highest amount of air draw at 921
liters per hour at five inches and lowest amount of air draw at 11 inches coming in at 468 liters per hour. Overall there was about a 49% loss in air from the lower operating
depth to the higher, and it looks as though the sweet spot for this particular skimmer is in those lower sump water levels and probably where I would personally install
it in my own system. Taking a look at the Regal
200EXT in a similar test, which utilizes the VarioS four pump in a recirculating configuration, who’s soul purpose is to draw in air, immediately we see hardly a change at all in air draw from five inches
all the way up to 11 inches, where there’s only a difference
of 17 liters per hour from the highest measured
air draw to the lowest and with similar numbers
throughout the operating depths, it’s easy to see how splitting the job of air intake and water
flow between multiple pumps creates even more
stability regardless of how you install it in your sump. One of the most eye opening
results we’re seeing here between these two skimmer designs is how much more air we’re measuring on the recirculating skimmer
over the single pump skimmer where the dedicated air draw pump draws in over 36% more
air versus the single pump dual duty design that
averaged 705 liters per hour across all operating depths. To demonstrate this max air draw average between the two skimmers even further, we placed each one in
seven inches of water then toggled the DC pump settings through its five different pump speeds and tested the air draw again. Starting with the Regal
200INT single pump design, we tested the lowest of the five settings to draw around 17 watts
and an average air flow of 283 liters per hour, power setting two tested at 22 watts and
441 liters per hour. Setting three tested at 28
watts and 590 liters per hour, at 33 watts and setting number four there was 705 liters per
hour average air draw and out of the highest
38 watt power setting, we see an average pretty
close to the first test of 811 liters per hour. Across all five power settings, we measured an average of
566 liters per hour air draw. Looking at the Regal 200EXT
recirculating skimmer which tested the same wattage
draws for each power setting, we see an increased air flow
at each of the five settings from 436 liters per hour at setting one, to 1,080 liters per hour at setting five, meaning that the total
average air draw overall for the dedicated pump came
in at 790 liters per hour or 40% more than the single pump design. So with adjustable DC pumps like these, we can see that there is an added layer of adjustability for both designs and that you can simply push a button to reduce the amount of air draw but just keep in mind that
in the single pump design, a reduction in the amount of pump speed not only reduces the amount of air, but also reduces the
amount of water flow speed through the skimmer. For similar skimmer
designs using AC pumps, the same effect is achievable
for recirculating skimmers where you can simply install an air valve on the recirculating pump
and open and close the valve to let more or less air into the body, yet on a single AC pump skimmer, controlling the air draw with a valve in a similar fashion creates a situation where every reduction in air will have a corresponding increase in water flow and decrease in contact time. We actually tested this ourselves using three RedSea RSK 300 skimmers that utilize the Sicce PSK 600 AC pump with them tuned to 150 liters per hour, 300 liters per hour and 600
liters per hour respectively. Visually, you can see
the higher flow rates going through the skimmer where the air was turned down to 150 liters per hour. There was definitely less air, but way more water flow which ended up pushing more microbubbles
out of the skimmer body and into the tank so while
you can tune air flow to some degree on a single
AC powered skimmer pump, be aware that you might
be flushing more bubbles out of the skimmer at those
extreme ends of tuning. After seeing today’s data
between all these skimmer types, it’s pretty obvious to me
that the increased levels of adjustability from a
recirculating skimmer design doesn’t make it harder to
implement and use on a tank, particularly those with
push button DC adjustments, but rather it makes the
filter or foam engine more tunable to my particular system and in turn easier to dial in properly which is why I’m rating
today’s question of, is a recirculating skimmer more stable and easier to tune than
a single pump skimmer a ten out of ten on the
reef certainty scale but we’re not done yet. Phase two of today’s testing
is just around the corner. As I mentioned earlier, there are some challenges associated with each skimmer design, both recirculating and
single pump skimmers where for the recirculating design, there’s typically an
associated cost increase. For many reefers, whether
it’s your first tank, second tank, dream tank,
or all of the above, the costs can be a major
point of consideration for not only the equipment you
decide to use on your tank, but even the impact of
load on your living space and where your tank will
ultimately be placed so that it still provides
enjoyment for you and those who see it,
while also being in a place that’s structurally sound and makes things like tank maintenance easier to perform. If you wanna see how
Ryan plans to approach this very challenge on his
own 360 gallon dream tank in his home, check out yesterdays video from the ongoing BRS 360 series.

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12 thoughts on “Is two better than one? Is a recirculating protein skimmer extra cost worth it? | BRStv Investigates

  1. More from BRStv Investigates!

    ➡ Skimmer Air Test Round 1 : https://brs.li/BRStv_SkimmerTesting_Rnd1

    ➡ Skimmer Testing Part 2: https://brs.li/BRStv_SkimmerTesting_Part2

    ➡ Make your own fish food! DIY Reef Chili : https://brs.li/BRS_DIY_ReefChili

  2. How are those ratings created, Varios 4s with a rated airflow of 1500 lph yet doesn't come anywhere close to that rating even on the recirculating one (still not sure why you think putting an external pump inside a sump says anything though), but at the recommended operating depth it pulls less than half of the rated air flow, at which point seems kind of misleading to even put airflow ratings on these skimmers at this point. "Hey we can put anything we want on there, even though you won't get that… EVER… not even in the most ideal conditions"

  3. Ive owned all the different skimmers. In my opinion a nice cone skimmer in the right amount of water and tuned properly will make life easy as long as it gets proper maitance .

  4. I have questions about using airdraw as a measure. Bubble size is more important than sheer volume of air pulled, and ultimately the skimmers ability to draw ‘nutrients’ out of the water is the purpose here. Could you not devise a test where you compare the speed it takes the skimmer to pull crap out of the water? I’m just not 100% solid on the validity of air draw as the best measure of skimmer performance. And before people get triggered this isn’t a criticism and I’m open minded to your answer BRS but just not sure about your approach being the best way

  5. You stress the tunability of both types and the various air flows achievable,. It might be an idea to show how to properly tune both types for maximum efficiency

  6. you are asuming air flow equals organics removal which it isnt, theres another variable air buble size, so airflow alone isnt that great as a measure

  7. A feature I always look for in a skimmer is that the outlet will remain completely above any foreseeable water level in the sump. The change in back pressure on the outlet can have a drastic impact on tuning as you've seen in your tests.

  8. It might be worth mentioning that more air isn't always better skimming. Over 13% air by volume and the bubbles start to coalesce and you have a reduction in air-water surface area. [per "Aquatic Systems Engineering" by P.R. Escobal]

  9. Can u please make a video about best skimmers of 2019 like other best of reef tank gear series u made recently.
    Cheers!!

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