Many of the corals we keep in reef tanks pull calcium and alkalinity out of the water to build their skeletal structure and grow. As you add more corals or the corals you have grow larger, the calcium and alkalinity consumption only becomes greater.


If you replace the calcium and alkalinity as needed, the corals will grow fast. If you don't, they will grow slow and struggle to survive. It doesn’t really get any more complex than that.


Two Part Solution


Two-Part Solution

This is another area of reef keeping in which there are multiple effective methods to get the job done, we are going to show you the most popular method which is using a two-part solution.


“Two-part” is simply one jug of calcium solution and one jug of alkalinity solution. You can use any brand you like, all of which will give you similar results. We are using the BRS Bulk Pharma Two-Part mostly because it is the most popular option we carry. This is likely due to the fact that it is hands down the most affordable method, is made from pharmaceutical grade chemicals and we have a calculator on our website that makes it super easy to use.


BRS Pharm Two Part Solution


How to use BRS Bulk Pharma Two Part

BRS pharma comes in a dry powder form, you just measure it out and add purified RO/DI water to make a one-gallon jug of solution. The solution is then added to your tank and once mixed, the one gallon of solution will likely last you months. You can even forego the measuring part and just purchase the single-use packets that are pre-measured to mix up one gallon of solution.


BRS Bulk Pharma Soda Ash


The concept is really simple so don’t overthink it or let yourself get intimidated. Not many of us are chemists or experts on water chemistry and all of this may seem complicated at first but in reality, it is quite simple once you get the process down.


Start by testing calcium and alkalinity every week with quality water test kits. The tests take 2-3 minutes each and really help you to see how all of this works.


When calcium levels drop, add the appropriate amount of calcium solution and the same goes for alkalinity. Use the reef calculator on our website to determine how much solution to add based on your tank’s levels, desired target level and total water volume.


Phosphate Levels of Cured Rock


How to Use the BRS Reef Calculator

The reef calculator process for calcium and alkalinity are almost identical. The steps below refer specifically to calcium and just follow the same steps for alkalinity. Be sure you choose the right selections and enter the correct values before calculating.


1.Choose “Calcium” from the first drop-down menu

2.Choose “Liquid Calcium Chloride”

3.Choose “New Pharma Pouch”

4.Enter your tank’s total water volume, current calcium levels and finally the desired calcium level

5.Click calculate for the amount of solution required to bring your tank’s levels up to the desired level.

6.Dose above amount into your aquarium as directed


Calcium and Alkalinity Levels


Every experienced reefer ends up with a set of parameters or calcium and alkalinity levels they prefer to keep. For new reefers, slightly higher levels are ideal because you get a little room for error before running into dangerously low levels. 440 PPM of calcium and 9 Dkh make for an ideal target range.


Red Sea Test Kit


Water Testing

In the beginning, with just a few corals, you can probably get away with testing every other week but once a week is best, at least until you get the hang of it and understand your tank’s demand for calcium and alkalinity.


Among the two, alkalinity is more important just because there is less of it in the water to begin with so depletion to dangerous levels can happen faster. A solid compromise would be testing alkalinity weekly and calcium every other week.


Red Sea Test Kits


Red Sea makes our favorite calcium test kit and Salifert for alkalinity. A reasonable investment into the Hanna Instrument Dkh (alkalinity) Checker Colorimeter is a smart option because you can get an easy digital readout of your alkalinity in 60 seconds. Just about every reefer eventually ends up with a Dkh Checker and often times their tank benefits from it. If the test is easy to do, you are far less likely to neglect it.


BRS Drew's Doser


Using Dosing Pumps

As your tank matures and you add more corals, you will find yourself dosing more frequently to keep your levels within range. Eventually, it is worthwhile to pick up a couple of automatic dosing pumps to deliver the solutions for you on a daily basis.


Many hobbyists set up a dosing pump right out of the gate just because it simplifies the dosing and makes your life easy.


Hanna Instruments Checker Colorimeter


To calculate a daily dosage, test your alkalinity today and then test it again tomorrow at the exact same time of day. The levels will drop and then head over to the BRS Calculator to determine the correct dose to bring your levels back up.


That is your daily dose of the solution and what you will set the dosing pumps to deliver daily. In this case, the amount for both calcium and alkalinity should be the same from each doser. Before turning on the dosers, be sure your levels are balanced.


Programming a dosing pump


After the first few days, test your tank again. If the calcium or alkalinity levels have dropped you need to increase your daily dosage in very small increments. If it rises, decrease the daily dosage. It usually takes 2-3 repeated tweeks like this before you have the dosage perfectly dialed in.


If you want even more details on supplementing calcium and alkalinity, we have a slew of other videos on the topic to help you become an expert.


What’s Next?

Next up on the 5 Minute Saltwater Aquarium Guide playlist is how to deal with evaporation, something every single tank owner needs to master.


5 Minute Saltwater Aquarium Guide Episode #20


Looking for a different topic or have questions? You can binge the entire 5 Minute Saltwater Aquarium Guide playlist right here on our website. We also invite you to join the #askBRStv Facebook Group which is a free resource for you to ask questions, get advice, interact with other hobbyists and get your daily reef aquarium fix.