- Today on BRStv Investigates,
will double the powerheads and double the flow
result in faster growing corals?
What about double the powerheads and quadruple the flow?
Let's find out.
(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 update,
we'll share the results that we've been gathering
for the last four months of testing coral growth rates
in tanks with low to medium flow
versus tanks with high flow.
Today we'll get a clearer picture
of measurable differences in coral growth, if any,
between lower-flow and higher-flow tanks,
which should reveal itself in differences
by the daily amount of calcium and alkalinity consumption.
Or even more so by the actual mass or weight
of the corals from tank to tank.
And at the end, let's see if our eyes
can tell any difference in growth by looking
at visual comparisons across the tanks.
It should be pretty interesting.
Open and honest, from the outset of this test
I was pretty certain that we'd see undeniable differences
in growth between low-flow tanks one and two
versus high-flow tanks three and four.
Which is certainly what almost everyone
in the hobby would also suspect.
But let's see how close my guess was as we look
at the data we've gathered so far,
in an attempt to answer the question,
will increasing the flow in your display tank
by two to four times result in faster coral growth?
Because flow is such a vital component
to almost every major function in our corals,
including balancing chemistry within and around the corals,
providing a delivery mechanism for food and nutrition
to reach the coral's polyps and tissues,
as well as aiding in the removal of waste,
and photosynthetic byproducts away from the corals.
I'd venture to guess that many reefers would agree
that the right amount of flow inside the tank
should result in improvements to coral health,
coloration, and metabolic function.
And if that were the case,
we'd also expect to see an increase
in coral calcification and growth.
So it's in that spirit that we set up a four-tank experiment
with two opposite flow rates,
in order to see if we could put some validity
to the notion that increased flow
will yield increased growth.
Let me show you how we planned to approach this one.
As Ryan laid out in the introduction video
to our flow experiment test,
we have four Red Sea E-170s,
each with two Ecotech Radion XR15s,
set to their popular AB+ spectrum.
Neptune Apexes complete with DOS dosers for auto water
changes and for supplementing alkalinity and calcium.
Brightwell bricks at the bottom
of each tank for biological filtration.
And finally, almost a hundred corals with each tank,
getting 24 test corals, all donated by ORA.
I'll tell you right now that the captive bred
and raised nature of the ORA corals,
and the availability of nearly exact replicas
of similar coral species have worked out so far
to make this one of the easiest experiments we've done.
Especially given that out of nearly a hundred corals
in a newly setup bare-bottom tank,
which can be some of the most challenging environments
for corals to thrive, we've experienced
zero mortalities across the board.
Okay, so we setup two redundant experiments
in order to compare the results from tank one to tank three,
and tank two to tank four.
Tank one and two will be the low to medium-flow test tanks
that are fitted with two Vortech MP10s,
running at 100% reef crest mode
for an approximate max turnover rate
of 3,000 gallons per hour.
Which on this 45 gallon E-170,
works out to be around 66 times turnover.
On tanks three and four we'll double up on the MP10s
for a total of four on each tank.
Which will give us a max flow rate capacity
of around 6,000 gallons per hour or 132 times turnover,
with them also set to 100% reef crest mode.
With a couple of months worth of data in the books,
let's take a closer look at what we found again,
by looking at the daily calcium and alkalinity consumption,
by comparing how much calcium chloride
and sodium bicarb was dosed to the tanks,
and then weighing each coral individually
to compare the combined mass percentage gained in each tank.
Starting with differences in calcium
and alkalinity consumption rates,
with 50% less flow in tank one compared to tank three.
At the end of two months we can clearly see
that even with double the flow turnover inside the display,
the corals in tank three really
didn't consume much more than tank one.
And when comparing tank two to tank four,
we see nearly identical results across the board,
which at face value seems like no real difference in growth.
But let's take a look at weight of the corals themselves
and see if it tells a different tale.
Okay, so I won't bore you to death
with a 96 coral by coral breakdown
of the weight across all four tanks.
Instead, we'll just observe the total combined
weight increases from when the corals were first added
into the tanks to their weight after two months
of being exposed to two significantly different flow rates.
Getting right into it we see that after two months,
the low to medium-flow tank one gained 19.66
in overall coral weight.
Which is pretty awesome if you ask me.
However, at nearly double the amount of flow happening
throughout tank three, there was only an average of 25.52%
weight gain, for a slight increase of a little over 5%.
In our redundant experiment,
the lower-flow tank two corals gained 29.12%.
However, the higher-flow tank four showed
even less growth at just 22.88%.
So with these results combined,
I'd say that in terms of weight or mass gained,
we're also seeing no significant difference
between high versus low-flow tanks.
But wait, we're not done yet.
Alright, so after what we've seen so far,
we could just go ahead and rate this one
on the reef fantasy or reef certainty scale,
but we thought we'd add another dimension to this test
and see if we could really get some measurable results
from varying the flow rates in our tanks.
So with that in mind,
we took this experiment to the next level.
After seeing the results of two months of coral growth,
we increased the flow gap
between the two redundant experiments
by reducing the reef crest intensity from 100% down to 50%
on the low to medium-flow tanks one and two
for about a difference of four times less flow
than the high-flow tanks three and four,
and ran the experiment for another two months.
Let's see if the growth story has changed.
Right outta the gate we see that tank one and tank three
ended with nearly identical daily doses
of calcium chloride and sodium bicarb.
Which are both about 20 mils per day of calcium
and 45 mils per day of bicarb.
Tank two and tank four echo similar results
in their daily consumption.
Both ending pretty close to the same daily range
as tank one and tank three.
I have to say that I'm pretty surprised
that we aren't seeing a dramatic difference
between 33 times tank turnover inside the display
versus 132 times tank turnover,
which almost certainly the reefing community,
including myself, would have expected.
But let's review the coral weight differences
at these flow rates to be sure.
Again, after another two months of experimenting,
much as I suspected, from the consumption results,
comparing the 12.15% coral mass increase in tank one
to the 20.22 gain in tank three
isn't overwhelmingly dramatic.
Especially when you couple that with the 1% difference
between the low-flow tank two,
which had a 15.28% increase in weight versus tank four
that only edged out an additional 16.59% gain.
So now we've seen the data for two different experiments
showing very similar results.
But what about the visual look of the corals themselves?
Will our eyes be able to pick up on any visual cues
of growth differences between one flow rate to another?
Here are some side-by-side comparisons of all four tanks,
comparing tank one to tank three and tank two to tank four,
after four months of different flow rate testing.
I'll let you decide for yourself
if you can pick up on any changes.
(light upbeat music)
I think that after what we saw here today,
in terms of increasing flow in your display
by two to four times, resulting in faster coral growth.
I think it's really tough to rate this one
more than a three on the reef fantasy scale.
And the only reason it's not a one is that our results
that we gathered in the last few months
really defies so much common thought about flow.
That includes numerous anecdotal accounts
from hobbyists to leading coral farmers,
as well as what other institutional research has produced
in terms of varying flow rates and coral growth.
A couple of things that this test didn't touch
are the differences between our artificial testing
environment and the actual home reef tank,
where variables like aquascape and the dead spots
it can create affect the overall flow patterns in the tank.
This isn't something that we attempted
to replicate here in our experiment
and why I still would rate this one
a three instead of a one.
My biggest takeaway here is that at the bottom end
of seemingly common flow rates for SPS corals
at just 33 times turnover,
we're still seeing similar growth results
as four times that amount of flow at 132 times turnover,
when unobstructed by rockwork or substrate.
So if we're able to achieve 33 times turnover
in all parts of the tank, including dead spots,
this might work in a real world tank environment.
You know, although we didn't find a massive difference
from today's experiments, we might let
this one play out a bit longer with even less flow
or the added variable of some aquascape.
But there is one thing that we do know for sure
from the data we've gathered in other experiments like this,
and that is that there's definitely elements of the tank
that we could control and manipulate as hobbyists
in an attempt to gain an edge in our tanks
that actually produce eye-opening results.
A shining example of that was the data we gathered
in this experiment of elevated alkalinity, calcium,
and magnesium levels, that I'm sure you won't wanna miss.