Here are some of the most frequently asked questions and concerns about recognizing when you have a coral RTN and how to prevent and stop RTN.

How do I know if my corals have RTN and STN parasites.?

Common signs of infections are:

  1. Coral Bleaching.
  2. Any tissue loss (RTN/STN/Brown Jelly).
  3. Polyp closed or retracted.
  4. Retracted tissue.
  5. Melting polyps (zoanthids, leather, mushrooms, and all soft corals).
  6. Coral color loss.

My tank looks great, do I need to do any treatments?

We recommend a maintenance treatment of the entire system every 2 weeks with Prime Coral Prevent RTN. Follow these directions.

What do you recommend for new corals?

We recommend dipping all new corals with Prime Coral STOP RTN dip prior to putting it into your system. Repeat the dip once more 3 to 5 days later. Then mount your coral. Follow these directions.

What does Prime Coral STOP RTN dip treat?

RTN and STN microscopic parasites, acropora eating flatworms and nudibranchs, montipora eating nudibranch, polyclad worms, black bugs, common flatworms and eggs.

What is the shelf life of Prime Coral STOP RTN unmixed?*

The shelf life of unmixed bottle is 6 months.

What is the shelf life of Prime Coral STOP RTN once Bottle A is mixed with Bottle B?*

The shelf life of the mixed bottle is 4 weeks. This has been verified with quality control testing.

How do I mix the Prime Coral STOP RTN Treatment?

See here for video.

Once the Prime Coral STOP RTN mixture is added to the container with tank water for coral dipping, how long is it good for dipping corals?

 6 hours

Do I refrigerate the Prime Coral STOP RTN bottle?


Do I refrigerate the Prime Coral Prevent RTN bottle?


Will the Prime Coral Prevent RTN in-tank treatment harm any beneficial reef creatures?

No, except for fish.

Can Prime Coral Prevent RTN PRO (professional strength) be used in a system with fish?

Absolutely Not.

Do I turn off my protein skimmer during the in-tank treatment with Prime Coral Prevent RTN?

No. Keep your skimmer running. Remove the skimmer head and allow the skimmer to overflow into the sump. Open the skimmer outflow valve all the way.  Return the skimmer head and adjust the outflow valve to its normal position gradually after 6 to 12 hours. If you do not have a skimmer, use 1 air stone for every 50 gallons of actual tank water volume.

Will the Prime Coral Prevent RTN in-tank treatment harm my fish?

We recommend not to treat systems with fish however, most healthy fish will not be affected if the directions are followed properly.

Can Prime Coral Labs tests my corals with tissue necrosis for the presence of RTN or STN parasites?

Yes. Purchase the Coral Necrosis Analysis kit.

Why would a coral die even after treatment?

Some corals that are heavily infected with the parasites will not survive the treatment. The treatments do not cause harm to healthy or uninfected corals.

Do either treatments, Prime Coral Prevent RTN and Prime Coral STOP RTN, harm normal corals?

NO. Prime Coral Labs has preformed extensive testing on normal corals and anemones. Un-infected corals will not be harmed as long as the direction are followed.

Can I use both, Prime Coral Prevent RTN and Prime Coral STOP RTN together to treat infected corals?

Yes, we recommend that you use both products. You will not eliminate all parasites out of your system if only one or the other is used. 

How many in-tank treatments are necessary?

You can treat you system every 2 to 3 days with Prime Coral Prevent RTN until all signs of coral disease are gone.

What factors determine the length of the in-tank treatment will be?

Many, see here.

What are the RTN and STN parasites?

They are microscopic ciliated protozoan parasites that infected corals, anemones, and clams and cause serious illness that results in coral death through tissue necrosis. See CoralRTN for more details.

*Bottles must be refrigerated.