Today on BRStv Investigates we start down a path of investigative tests to figure the
ins and outs of how calcium reactors work, in order to make them easier to understand
and easier to implement on our tanks, by starting first with a series of tests that will probably
cover a half a dozen or more main components of using a calcium reactor, like tuning one.
Hi, I’m Randy a host for the popular YouTube series BRStv Investigates where we take popular
reefing theories, methods, questions, & products and dive even further than what the manuals
and packaging will tell you; in order to put them to test in real world environments; rate
them on our scale of reef fantasy to reef certainty and share with you, the reefing
community, what we find.
Today we seek to answer a couple of questions to better understand the relationship between
the pH in the body of the reactor and the potency of the effluent it creates by answering...
“Do calcium reactors have a max saturation point?” and “Does that saturation point
scale up or down in relation with the pH inside the reactor?”
As most reefers know or have come to learn through the progression in the hobby, at some
point in your reef tank’s life you’ll need to supplement and maintain Alkalinity,
Calcium and Magnesium as your corals grow and thrive.
That said, out of the three most common approaches to provide these additives to your tank (between
2-part, kalkwasser and a calcium reactor); the first two have been proven to not only
be scalable and effective but also have been proven to be the easiest methods for a wide
majority of reefers who use them.
However for the calcium reactor, which has also been proven to be equally as effective
and scalable, and has bonuses like trace elements and no effect on salinity; knowledge on how
to use them seems to be a barrier to entry.
With that in mind, we aim to test a variety of questions surrounding a standard calcium
reactor in order to make them more accessible to those reefers who’d like to use one on
their tank.
In order to accomplish this, we thought we’d first look at how pH inside the reactor effects
the potency of the solution, meaning how much Alkalinity and Calcium is in the effluent
we are dosing to the tank.
Because the suggestions for choosing a target pH in the reactor are all over the place,
rather than vague statements of whether or not to adjust higher or lower, we want to
see if we can find a window into what the different pH rates are really producing in
terms of dKH saturation so you can make more informed decisions on using it with your tank
and better understand what those changes are doing.
Here’s how we plan to get it done.
Using a Vertex Calcium reactor filled with Two Little Fishies Reborn reactor media, we’ll
set the reactor pH to a range of 6.2, 6.3, 6.4 and so on, all the way to 7.2 then test
the effluent concentration for each point after letting it run for a full 24hrs.
We’ll test the effluent from each pH point with the Hanna Alkalinity checker, which has
a max range of 20dKH, so if any of them exceed those ranges we’ll simply dilute the sample
with RODI water and calculate the saturation accordingly.
We also plan to use Tropic Marin Pro salt for the tank water that feeds the reactor
which has an Alkalinity of 7.2 when we tested.
Finally, we plan to use an extremely slow 5ml/minute flow rate, so that the rate of
flow has minimal to almost no impact on the results.
The goal with this is to remove flow rate from the equation as much as possible, but
then explore the effects of adjusting those flow rates in future tests to identify and
further explain how the two (pH and effluent flow) interact to produce a combined result.
To start the test we pegged the pH at 6.2 which is relatively lower than what we’ve
seen commonly recommended for Calcium Reactor set points and then let the reactor run for
several days until it capped out around 54.4 dKH and then began to increase the pH by 10th
of a point increments tested again after 24hours.
The first jump in pH to 6.3 inside the reactor after 24hrs resulted in a max saturation average
of 45.4 dKH so a loss in 9dKH total.
At 6.4pH, we see another fairly high drop from 45.4 to 40.4dKH which is a change of
exactly 5dKH; followed by an almost similar dKH drop from 6.4 to 6.5 where we ended up
with 35.6dKH or a change of 4.8 total.
At 6.6pH we continue to climb down the saturation chart with a change of 6.3 dKH from 35.6 to
29.3; and then a less dramatic decrease between 6.6 to 6.7pH where we averaged the reading
at 25.7dKH for a total loss of 3.6 between the two.
From here we begin to see continued decrease in the max saturation, but in smaller increments
as we climb the pH scale starting with a 2.9dKH drop from 6.7 to 6.8pH where at 6.8 we saw
22.8dKH concentration.
After 24hrs of being set to 6.9pH, the Alkalinity falls under 20 to 19.8 and then at 7.0 we’re
down into the 16.6dKH range; showing small decreases in 3 and 3.2 dKH respectively.
Finally, for the last two pH ranges of 7.1 and 7.2 we tested a 4.1dKH fall to 12.5 when
set to 7.1pH followed by a 2.1dKH drop to 10.4 for the final 7.2pH increment.
I would note here that the initial Alkalinity of the Tropic Marin Pro salt we used was at
7.2dKH which was only 3.2dKH away from the saturation level at the pH increment of 7.2,
so it’s where we decided to end the testing.
So looking at the data for each pH point and answering our two questions today of, “Do
calcium reactors have a max saturation point?” and “Does that saturation point change with
the pH inside the reactor?”, I’m going to have to rate this one a 10 for Reef Certainty
on both fronts, as we can absolutely see that there seems to be a max saturation point for
each pH range at our fixed flow rates.
And with that, each one changes incrementally at various changes in pH set points.
Ok, so what does this mean for reefers?
I think most can use this info to draw a comparison in relation to their own tanks to better understand
the Alkalinity and Calcium concentrations they’re dosing to the tank when selecting
a specific pH set point, and make more informed decisions as to how it all works together,
especially with the same Two Little Fishes Reborn media we used for testing.
From the results we’ve seen here today, I’d say that the range of 6.2 to 7.0 (that
most of the industry suggests for pH set points in the calcium reactor) are pretty solid with
measurable differences between each point, which could help better fine tune our own
tank’s pH set point down the road.
However, with the largest of jumps coming from the 6.2pH range to 6.3, this might lead
me to believe that this is a point close to where the CO2 begins to melt the media faster
than what an average tank might be able to consume.
Overall there’s an average of 4.4dKH difference for each 10th of a point in pH range and the
change in potency is slightly higher from 6.2-6.6 versus the slightly less drastic changes
in dKH between 6.6 and 7.2….meaning that below 6.5 the saturation climbs faster, which
again may be the start of ranges where the media starts to melt too fast and builds up
the mush in the reactor that some reefers talk about, which of course will also depend
on the media type and granular size.
I would note the significant jump of 9dKH between 6.2 and 6.3, which could be in part
because it was the starting point and we let it take about 3 days to get there, but it
could also be because the media just starts to dissolve fairly rapidly at this low of
a pH.
Looking at the most commonly recommended pH set point ranges of 6.5 to 6.8, the difference
in max saturation is a 50% increase from 22.8 at the higher pH to 35.6dKH at the lower pH,
which probably hits a vast majority of reefer’s tank demands depending on the flow rate they
choose.
Along with that we see that at a pH above 7, the dKH saturation is getting pretty close
to the starting point of 7.2dKH from the Tropic Marin Pro saltwater, but could probably be
used on a low consumption tank for a more extended period of time if you wanted to.
Alright so what’s next for this series of tests to determine the relationship between
CO2 contact time ad max saturation points?
We’re going to add in the variable of different flow rates on three of these pH points with
6.4, 6.6 and 6.8 to see how faster flow through the reactor affects contact time and to what
degree that change will have on the max saturation points we determined from today’s testing.
Reefers commonly share that increasing the flow through the reactor to the tank will
decrease contact time with the media and reduce the potency of the solution; and we agree
that there has to be some truth to that… but by how much?
Answering that question will help us understand the balance of flow rates and pH points and
ultimately help make calcium reactor setup easier.
Of course a lot of this data is dependent on the size of the reactor and how much media
& water is in it, but this Vertex reactor is a good representation of an average reactor
and will likely be relatable to a higher percentage of average reefer’s tanks.
Finally, head on over to our Reef2Reef post for this BRStv Investigates test and vote
on our poll asking Calcium Reactor users, “what is the pH set point you aim for with
your calcium reactor?”
Also, if you have a calcium reactor related question or something you’d like to see
us test in future BRStv Investigates episodes, drop a comment below leave us a comment in
the Reef2Reef community forum or better yet jump on our #AskBRStv FB group where the BRS
crew including Ryan and I get in there and answer your questions directly.
See you next time on BRStv.