- 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.