My understanding is that prime is effective for 24-48 hours and then releases the ammonia back to its original form.
I’m not sure that anyone knows for sure what in prime makes it toxic to fish when mixed with copper, but I’d highly advise against finding out.
It doesn’t appear that prime vanishes after 48 hours, rather it doesn’t serve its original purpose any longer.
Here’s a response from seachem to a different question from their forum that I am drawing my conclusions from:
“Hi Nat,
Thanks for your questions. You do understand correctly that Prime removes chlorine and chloramines; and it detoxifies ammonia, nitrites, and nitrates. It detoxifies these nitrogenous compounds by binding them into a non-toxic form. They stay bound for about 24-48 hours and then are released back into their original form.
In an established tank, your biological filter should remove ammonia and nitrite quickly. Prime will help keep it non-toxic until the bacteria can utilize it. Usually, small amounts of ammonia found in drinking water should be gone within the time that a conditioning dose of Prime remains effective, but if the ammonia persists, you can re-dose with Prime after 48 hours to keep the tank safe while the biological filter catches up.
You are correct that one dose will treat about 1 mg/L of ammonia, so you can increase the dose accordingly up to 5 times the regular dose.
Test kits will still show nitrites and nitrates even when treated with Prime. An ammonia test kit which shows total ammonia will also still measure the ammonia in the water. However, a kit that only tests for free ammonia (the more toxic form) will reflect a reduction in the free ammonia when Prime is used. Our Ammonia Alert (
http://www.seachem.com/Products/product_pages/AmmoniaAlert.html ) goes in your tank and allows you to easily monitor free ammonia. With an Ammonia Alert in your tank, you can quickly know when the Prime has quit working and re-dose if there is still ammonia that needs treating. An Ammonia Alert is great when you are cycling a tank.
Chlorine and Chloramines are removed permanently, so you don't have to worry about them after the initial treatment.
I hope this helps.”
And a link to the thread:
http://www.seachem.com/support/forums/forum/general-discussion/2431-questions-about-prime.
I’d recommend large water change and instead, using Dr Tims or Biospira to jumpstart bacteria (I have experience with both and find them to be phenomenal products) instead of prime. Also, avoid seachem stability, it’s not been remotely useful at seeding beneficial bacteria. It turned me off of bacteria in a bottle until I tried Dr Tims and Biospira, which, much to my surprise were very effective!
