FAQ: Is Seachem Prime® sulfinate- or sulfoxylate-based? It smells like sulfur, and the medication I am using says that it should not be used with these types of water conditioners.

Unfortunately, Seachem® is not able to disclose the proprietary ingredients of Prime®.  We are not currently able to identify any direct interactions between the declared ingredients of the products which make this warning and Prime®.

Several of the medications which make this warning contain formaldehyde, formalin, or malachite green.  Both formaldehyde and formalin are strong reducing agents which should not be combined with another reducing agent (like a water conditioner) of any kind - dosing of these types of products should be spaced out by at least 24 hours if carrying out large doses.  This is not because the products directly interact with each other to form a toxic chemical - it is because using multiple reducing agents simultaneously has the potential to reduce the oxygen content of the system.  We are not aware of any direct interaction between Prime® and malachite green.  Thus, if this is the only concern, it should be fine to dose the medication if at least 24 hours are given between the dose of Prime® and the addition of the medication.

That said, our fellow manufacturers of aquarium products are under no obligation to disclose their proprietary ingredients to us, and they can change their proprietary formulations at any time without informing either us or their customers.  While we can speculate based on public information on product formulations and our knowledge of chemical interactions, the only way we can know with 100% certainty that any other manufacturer's products are completely safe to combine with our products is to test the specific bottle which is under consideration.  If you believe that there is a risk that Prime® will interact with your medication based on a warning such as this, we would recommend swapping to a water conditioner which discloses the complete ingredient list for the duration of the treatment, confirming with the manufacturer of that medication that none of the listed ingredients will interact with the medication.

All Seachem® medications except Cupramine™ are considered safe to use with Prime®. 

See FAQ: Can I use Prime® together with ________? for more information.