Can an Algae Scrubber outperform a Protein Skimmer at excess nutrient removal? | BRStv Investigates

Can an Algae Scrubber outperform a Protein Skimmer at excess nutrient removal? | BRStv Investigates


– Today on BRStv Investigates
what happens to phosphate and nitrate levels after you
feed a combined 200 cubes of frozen food to four
test tanks for seven weeks? Coming up we find out just how effective
algae turf scrubbers are at managing phosphate and nitrate levels versus two tanks with no
filtration whatsoever. Obviously any filtration
is going to be better than not at all but how
effective is a scrubber and can it perform better than
just a protein skimmer alone? (upbeat music) Hi I’m Randy with this
Friday’s BRStv 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 answering the question, when it comes to removing
excess organic elements like phosphate and nitrate, is
a scrubber just as effective as a protein skimmer? Okay, sure a protein skimmer has a variety of beneficial uses outside
of just removing excess food that leads to excess
phosphate and nitrate, but within that context alone, could an algae scrubber
out perform a skimmer? This one is personally important to me since I recently revived
a 60 gallon cube ULM tank in my office and after
seeing the successes of using algae scrubbers on
tanks like Zack’s 60 gallon cube here at BRS where he’s chosen
to run his tank skimmerless or Sean’s 2000 gallon tank we just toured who uses four large clear
water scrubbers and a skimmer, I want to learn as much as
possible about scrubbers to find out if it’s a viable option for my own reefing approach. I’m sure there are many
of you out there like me who’ve been waiting for some
more in-depth information about algae scrubbers so today we start our
scrubber testing journey with a look at how
effective they are compared to a set of control tanks. Here’s how we approached our first test. As we strive to do with each of our BRStv
Investigates testing, we set up two redundant
experiments for today’s test with control tanks one and two
and test tanks three and four outfitted with clear water
scrubber CW50 algae scrubbers. Each side by side vertex testing tank has an average volume of about 40 gallons and to run this test, we fed each one cube of
frozen PE Mysis daily for a four week period then monitor the respective
phosphate and nitrate levels with little to no competition from additional filtration methods like skimmers or sand in the tank. Additionally we scrapped each of the scrubber test tank
screens once per week as would be expected
for the minimal amount of weekly maintenance for
the average reefers tank. Okay, so right up front, before
we get into those four weeks of results, after the initial four weeks, we ramped up the test
and doubled our feeding to two cubes per day for
an additional few weeks to see if we could find a limit to the algae scrubbers effectiveness. The results are pretty interesting so let’s dive into the numbers. As I mentioned we ran
redundant experiments with control tank one
versus test tank three and control tank two versus test tank four so with that, let’s take a
look at the phosphate levels for the first four weeks of our experiment where our nutrition input
was one cube per day in each tank. Starting with the first set of test tanks, I don’t think it’s any surprise
that we see how effective the algae scrubber test tank three wasn’t reducing the phosphate levels and maintaining them within
commonly acceptable ranges where in week one there was
nearly undetectable levels and then finish the test at
just 1/10 of a part per million whereas there was a steady
increase in the control tank one starting with .3 parts per
million and ending at 0.83 or eight times higher. The same story pretty much
holds true for the second set of redundant test tanks two and four. During the first four weeks of testing where we see control tank two starting at a similar .3 parts per million at one cube of food per day and then ends the test at 0.9
parts per million phosphate. However the algae
scrubber on test tank four was able to maintain
very low phosphate levels with the same amount of nutrition input where it started at 0.01 parts per million and ended at 0.08 or 11 times lower. We’ll come back and take a
look at nitrate in just a bit but it’s safe to say that algae scrubbers undoubtedly have a major
impact on excess phosphate at one cube a day nutrition
input but we’re not done yet. What happens if you
double the amount of food to two cubes per day? Will the algae scrubbers
be able to keep up? Looking at the first set
of test tanks one and three we see that tank one with
double the amount of food pretty much doubled in the
amount of phosphate build up by the end of the test where it started at 0.83 parts per million and grows to 1.69 parts
per million by week seven. Test tank three looks
to have a greater impact from double the amount of food where it rose from 0.08
parts per million phosphate up to 0.51 parts per
million which may suggest that we have reached the
export capacity for this size of scrubber however, still
remains about three times lower in phosphate concentration
overall versus control tank one. Redundantly in tanks two and four, there’s a nearly identical
tale with a control tank two gaining 0.86 parts per million
phosphate from week four to week seven where it starts
at 0.89 and ends at 1.73. Again, as with the first experiment, the phosphate in test
tank four also climbs with double the amount of food where it gains 0.43 parts
per million phosphate from week four at 0.08 to week seven at 0.51 parts per million. However, in the end, test tank four is still three times lower than the control tank without
any filtration whatsoever. As I mentioned we also
monitored nitrate levels for each of the tanks but
as we’ve come to learn from a multitude of
attempts at testing nitrate, it’s notoriously difficult
to test for accurately in salt water using our
hobby-grade test kits so for those who are
curious, here are the numbers for each tank throughout the
entire seven week period. Basically in both
control tanks one and two we saw a nitrate range between
five and 12 parts per million while in the test tanks three and four we registered right at
one or less than one parts per million
throughout the entire test. I’d rate our question of is
a scrubber just as effective as a protein skimmer when it comes to reducing excess phosphates and nitrates a full 10 out of 10 on
the reef certainty scale. For the sole purpose of
nutrient control alone, I’ve personally never seen
a skimmer remove nitrate and phosphate completely or as effectively when it was the solitary
filtration method. Obviously a scrubber needs to be sized to the nutrition input
and this smaller size seemed to be optimized to
one cube a day in our case but as long as it’s matched
to the feeding habits, it seems to be a viable stand
alone filtration approach. You know I’ve also never
seen a skimmer-only system that was able to effectively out compete the tank display lights
and prevent algae growth in the display all together. But given today’s results
with an algae scrubber, do you think the scrubber alone could help maintain a hassle
free and pristine display tank? Find out what happens in our next test when we turn on the lights in
the front of these test tanks and see if the scrubbers
are able to keep algae from growing on the rocks. You can catch that next experiment and all of our eye-opening refugium tests in this playlist over
here, so check it out.

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