Q & A

What is ICP?

The answer to this is deep. But let’s address it here in a basic way that is related to aquaculture. 


ICP stands for Inductively Coupled Plasma and describes a method of introducing your sample to the instrument that will measure it. It is used in chemistry, toxicology, and medical fields, as well as many other areas. There are several variations of instruments that use ICP, including ICP-OES and ICP-MS. The OES and MS acronyms identify different methods of measurement.

What is the difference between ICP-OES and ICP-MS? How does it matter to me?

ICP-OES and ICP-MS measure the elemental composition of samples using different methods. These differences allow ICP-MS to measure elements at smaller concentrations. Which one is appropriate for you depends upon your goals. If you are an expert reefer and want to get the highest possible accuracy so micro-adjust your elements, then ICP-MS might offer an advantage. However, being able to effectively utilize the extra sensitivity also requires more advanced skills and experience.

Do you offer ICP-MS test kits?

We have ICP-MS in our lab, and we are currently evaluating how best to offer an ICP-MS test kit. Just providing test results yields only some of the benefit. Providing helpful guidance and presenting the test results in a useful way is necessary to gain the most benefit.

What do you test for?

Currently we test for the following chemical elements: Al, As, B, Ba, Be, Bi, Br, Ca, Cd, Cl, Co, Cr, Cs, Cu, Fe, Ga, I, In, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Se, Si, Sr, Tl, U, V, Zn.

Do you test RO DI water?

Our test kits can be used for either saltwater or RO/DI, but not at the same time.

What are the results good for? What do I do with the results?

Elemental water testing provides visibility into the amounts of essential elements in your water and levels of toxic elements. Without ICP testing, there is no other way to obtain a complete picture of what elements are in your water. Marine life has evolved over millions of years to depend upon the presence of a large array of elements. To achieve maximum health, coloration, and growth, it is necessary to ensure you have these elements present and in the correct amounts. Use the results of your ICP test to determine if you need to take action to remove contaminants or to determine what elements are missing and need to be supplemented.

How often should I test my water?

It depends on your goals. If you are just starting out, once every 2 months is a good place to start. But if you are trying to get the most growth and coloration possible, or if you have an established tank with years of growth, then every 2 to 3 weeks is more appropriate. Consider ICP testing to be an insurance policy to protect your valuable corals and reef inhabitants. It is a small price to pay for the peace of mind that your tank is stable.

Where can I buy the Reef Labs ICP test kits?

Places where you can find Reef*Labs lab-grade ICP tests increase every day, please check the “Where to buy” section of our website for a complete list of physical retail and online stores. If you don’t see your favorite retail store listed, please let us know, and ask your local store to contact ACI Aquaculture, our exclusive distributor, so that the store of your preference can obtain the Reef*Labs lab-grade ICP tests at wholesale cost.

How long after collected are the water samples still good for testing?

The water samples are viable for approximately 1 year without any detectable change in results. Because ICP analysis is an elemental analysis, the pre-processing of the sample ensures that any changes which take place while in transit do not affect the results.

Why are there two vials in the kit?

We provide two sample tubes in each kit which are intended to have the same sample water in both. We do this for several reasons. It is not uncommon to see a tube get damaged or leak in return shipment to us. Having the spare tube ensures that we are still able to test your water. For this reason, we feel it was better value for the customer to have the redundancy of two sample tubes with the same water sample.

How long does it take to get my results?

USPS delivery can take anywhere from 2 – 5 days depending on where you are located. After we receive your kit, we usually return the results in less than 3 days.

May I use the return label to send several samples?

Our return labels are calculated for the weight of one set of samples (2 tubes/vials). If the weight exceeds that amount, USPS may reject the package or collect extra postage upon delivery which will delay your results. For this reason, we always advise you to include only one kit per return label.

Where is my sample?

If you have notifications enabled on your account, you’ll receive an email as your kit progresses through the USPS system and when it arrives at the lab. You may also login to your account to see the current location or status of your kit.

Why don’t you test alkalinity and nitrate?

We do not test for alkalinity or nitrate for the following reasons: 

  • Alkalinity is very sensitive to gasses dissolved in the sample, such as CO2, and the pH of the sample. Both pH and dissolved gases can change significantly once a water sample is placed in a sealed container. Additionally, biological activity from bacteria in the sample will alter the pH, dissolved gases, and nitrate in the sample. For this reason, any measurement of alkalinity or nitrate will be inaccurate. It is possible to solve this problem, but it requires a specialized procedure for collecting the sample. Outside of a laboratory environment, it would be very difficult to ensure consistency and reliability of results this way. 

  • Nitrate is a food source for bacteria and thus is likely to change while your sample is transported. This would make any test result of nitrate inherently inaccurate unless the sample is treated at the time of collection to destroy any live bacteria present in the sample. However, as above, employing any special treatment to the sample potentially introduces inconsistencies and errors in results. 


We take great care to ensure that your results are as accurate as possible. This includes using a process that is adapted to eliminate as many potential sources of inaccuracy as possible.

Where should I take the water samples from?

It is best to take samples from beneath the water's surface in the display tank, not in the sump, and in a high flow area. Be sure to rinse the tube with tank water three times before taking the sample, and ensure the tube is completely full with water.