There has been an ongoing discussion over the topic of what levels for alkalinity, calcium and magnesium are the most ideal for coral growth with the general idea being that elevated reef tank parameters will produce increased coral growth. More or less the thought process is that the more available alkalinity and calcium in the water, the faster a coral can use them to build skeletal structure since the overabundance would allow the coral to use less energy to uptake them.

BRStv Investigates Clip

The BRStv Investigates crew has been on a mission to test this theory and if you have not been following along, here are some quick links to the first two episodes to get you caught up!

We certainly learned a few things during that first round of testing, most importantly that the systems with elevated parameters did in fact show more growth, actually to the tune of 70% or more!

With such a significant increase in growth and using what we learned during the first round of testing, we decided to run an additional experiment that more closely resembles conditions in a home reef aquarium. This time around we used rock instead of frag racks and typical aquarium equipment a modern reefer would use with the ultimate goal of helping hobbyists like you take your corals from frags to colonies in less time.

BRStv Investigates Clip

The Experiment

We set up two Red Sea Max-E170 aquariums with similar aquascapes using 25-30 lbs of Marco Rocks Reef Saver Dry Rock. Each tank is being lit using a single EcoTech Marine Radion XR30w G4 Pro LED light with the diffuser accessory and mounted using the RMS Tank Mount Kit. For internal water flow, each system has a single EcoTech Marine MP10 VorTech set to operate at 100% speed under the Reef Crest operational mode.

Each system has a Neptune Systems Apex Aquarium Controller with two DOS dosing pumps. One of the pumps is being used for small-percentage daily water changes in order to manage nutrient export and trace element replenishment. The other DOS pump is delivering BRS Pharma 2-Part Calcium Chloride and Sodium Bicarbonate for major element supplementation and Magnesium levels are being maintained manually as needed.

BRS 2-Part Pharma Calcium and Alkalinity Kit

We chose to use Sodium Bicarbonate instead of Soda Ash (Sodium Carbonate) to somewhat eliminate the effects of elevated pH levels on coral growth which was researched in a separate BRStv Investigates episode.

Experiment Tank Parameters

We are maintaining the lower parameter system that more closely resembles what a majority of reefers will target and then the elevated tank with much higher levels of all major elements. All of the water parameters are being measured using hobby grade test kits.

Finally, each tank has the same 25 coral frags grown by the talented crew over at World Wide Corals. The species range from Acros and other SPS to popular LPS like Euphyllia and Acanthastrea.

BRStv Investigates Test Tanks side by side

The Results

After 4 months of keeping these tanks, the first thing you notice is the tank with elevated parameters on the is far more encrusted with Coralline Algae, almost completely covering the bare bottom of the tank which is an interesting observation in itself.

As you take a closer look, we really start to see the differences in the individual corals. Pay close attention to the typical signs of healthy coral growth. Specifically, the thickness and number of branches (SPS) or amount of new heads (LPS) as well as encrusted bases.

Fuzzy Lephrachaun Hydnophora

GI JOE Favia

Spitfire Favia

Purple Tip Hammer Euphyllia

Green Hammer Euphyllia

Favia sp.

Rainbow Acanthastrea

Rainbow Acanthastrea

Orange Psammocora


Incredible Hulk Leptoseris

Psammocora sp.

Corals like the Hydnophora and Psammocora show seemingly faster growth as they are a bit larger and more encrusted in the elevated tank. There also looks to be a few more heads on LPS corals like the Acans and Duncan.

Acropora Sp.

Frozen Tundra Lepastrea

Nuclear Grapes Acropora

Acropora Sp.

Acropora Sp.

Acropora Sp.

Yoda Acropora

Acropora Sp.

Acropora Sp.


Blueberry Fields Acropora

Green Slimer Acropora

The most noticeable differences are among the Acropora corals. In the elevated parameter tank you notice more substantial growth at the bases where they have encrusted well beyond the plugs onto the rockwork. Some are showing to have thicker mass and longer more numerous branches. The Green Slimer in particular is very noticeable in the amount of growth over the lower parameter tank.

Something to note is that we did encounter two coral mortalities in the lower parameter tank; the exact reason for this is tough to pinpoint but still worth the mind space.

Alkalinity Consumption Results

The differences in carbonate consumption required to maintain stable alkalinity between the two tanks is the part that really proves everything we have been working for. The elevated tank required substantially more alkalinity on a daily basis compared to the tank with lower parameters, 598% more to be exact! This means the corals in the elevated tank were consuming more carbonates on average which we can only mean one thing, more growth was occuring.

SPS Corals

What this means for you, the hobbyist

It is plain to see how the combined results from our various parameter experiments begin to show what is possible by keeping elevated parameters to gain an edge on coral growth.

From an alkalinity consumption standpoint, there definitely seems to be measurable benefits in maintaining major element levels at what some would consider to be the very high end of acceptable.

Do you or anybody you know maintain such elevated parameters such as 12 dKH? Share your experiences in the comments.

BRS160 Aquarium Full Tank Shot

To ride this edge safely is not for everyone because it doesn’t leave much room for error should something like an overdose happen to the tank. With such high levels, your are close to the maximum concentration of these major elements which would then precipitate out if levels climbed beyond that point.

We agree the findings are exciting but proceed with caution here, we encourage you to only increase your dosage very slowly around 1 dKH per month and of course only if you feel confident you can control the parameters precisely. Stability is ultimately going to be the key to long term success and stability means making as little change as possible.

BRStv Investigates Red Sea Test Tanks

What’s Next?

We are working on a couple of other experiments to continue to explore ways of increasing growth and coloration of captive grown corals. Such variables as water flow in the display, dosing amino acids, and more! If you can combine the results from this elevated parameter testing with some of the results we saw in our pH testing, just how different could we approach optimizing coral growth in our own reef tanks at home?

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