How to Do Two-Part Dosing in the Marine Aquarium

When considering a marine aquarium, you need to pay attention to the chemical balances within your aquarium, especially if you have a reef aquarium. Fortunately, when your calcium or alkalinity is out of whack, there are products available which can help return your tank to gold star status. Known as two-part dosing, this method allows you to add just the right amounts of supplements to maintain calcium and alkalinity levels that are correct for your marine aquarium.

What Chemicals Are Involved in Two-Part Dosing?

No matter what kinds of organisms reside in your seawater aquarium, the two most crucial parts of your water to watch for are the calcium levels and the alkalinity. While many kinds of fish probably get enough calcium with frequent small water changes, the corals and clams you might have in your tank need a great deal of calcium for day-to-day living requirements, perhaps more than they would normally receive with a simple water change.

Alkalinity is important in seawater because it helps the water resist too many changes which might cause the water to become more acidic. The alkalinity is a direct function of how much bicarbonate, carbonate and lesser amounts of other elements are available in your seawater. If your tank lacks the buffering abilities of carbonate, for example, the alkalinity of your water can fall below levels your organisms would normally experience in the ocean.

The Basic Equipment for Two-Part Dosing

Perhaps the most critical piece of equipment you need for two-part dosing is a really good test kit. Never guess whether your tank needs a certain chemical addition, since too much of even a good thing like calcium is harmful for your marine organisms. Two testing rules of thumb are to test your water frequently, and only test and dose for one supplement at a time, since seawater is a fine balancing act between various chemicals.

If you decide after testing your aquarium water that you need more calcium or alkalinity, a simple method for adding these elements is to follow a two-part dosing program, which includes a calcium supplement and usually a bicarbonate supplement that focuses on adjusting the alkalinity of aquarium seawater. Theoretically, the two supplements should be added in equal amounts as required, but sometimes you might need to add more calcium than alkalinity supplement, or vice versa. That’s where a good testing kit is critical.

The two supplements are delivered to your tank by means of peristaltic dispensing pumps, which release the supplements into the water in small doses daily.

How to Dose Your Marine Aquarium Tank

The two-dose supplements come in powder form in half gallon or one gallon bottles. When you decide to dose your aquarium, your first task is to mix up solutions of each supplement in separate jugs. Follow the mixing directions listed on the sides of your supplement containers. When mixing up your solutions, only use reverse osmosis water.

The best way to mix the supplement powders into the water is to add a little supplement at a time to the water in the jug, shake the jug, then add a bit more supplement, until all the powder is mixed in. This prevents the supplements from clumping on the bottom of your water jugs. If clumping occurs, put the jug in a sink of hot water for awhile to warm the water up, which should allow for easier mixing. Once you’ve mixed up your supplements, let the jugs sit for a couple of hours to allow them to finish dissolving.

To do two-part dosing, you need two dosing pumps, one for each supplement. The dosing pump pulls either calcium or alkalinity solution from your additive jug to your aquarium by way of your aquarium pump. Many dosing pumps can be set to automatically deliver a dose at a steady rate, which eliminates time consuming manual delivery.

When adding the two-dose calcium and alkalinity supplements to your aquarium, do not add the two doses at the same time. Instead add the calcium first, and then wait an hour to add the alkalinity dose. Also, when adding two-part dosing to your aquarium, start with small amounts and slowly build up until you reach the levels of calcium and alkalinity you desire.