[Stone]

In fish keeping there is a water conditioner made by SeaChem called  Prime, Prime "detoxifies" Ammonia NH3 to NH4+, ok all of this is prettymuch fact otherwise record amounts of fish would be dead. Here is the debate in the fish keeping hobby, some say the detox process lasts forever and your biofiltration(the nitrogen process) removes it, other claim that the detox process only lasts 48 hours. Which is it?

[Hunter2]

Ammonia NH₃ and also ammonium NH₄⁺ are poisson for fishes. The nitrogen compound have to be removed by oxidation to nitrogen.

[Borek]

Prime "detoxifies" Ammonia NH3 to NH4+

The only way of doing so is to acidify the water in the tank (that is, lowering pH). As pH of water is one of things you need to keep controlled, I would be rather cautious, especially if your fish/plants are one of those feeling better in higher pH. Unless it really works some other way.

some say the detox process lasts forever and your biofiltration(the nitrogen process) removes it, other claim that the detox process only lasts 48 hours. Which is it?

Impossible to answer without knowing what the Prime really is. I doubt it works forever.

[Arkcon]

Unlikely that it lasts forever.  There should be microbes in a well conditioned aquarium that will consume dissolved NH₃, NH₄⁺, which are practically one and the same from a chemical standpoint, and whatever nitrogenous compound Prime converts the above into.  But you will always depend on bacterial flora to remove nitrogenous wastes, this chemical just keeps it safer for fish for longer.

[billnotgatez]

Still searching for more info
But
http://www.seachem.com/Products/product_pages/Prime.html

Prime® is non-acidic and will not impact pH. Prime® will not overactivate skimmers. Use at start-up and whenever adding or replacing water.

[Borek]

I have based my answer on the info from the original post.

[Arkcon]

Emphasis mine.

Ammonia NH₃ and also ammonium NH₄⁺ are poisson for fishes.

Oh, you.

[Sapperdaddy]

not sure if this helps, this is the important section. the entire MSDS is attached.
MATERIAL SAFETY DATA SHEET
Prime
Section I: MANUFACTURER’S NAME, ADDRESS, AND CONTACT INFORMATION
Seachem Laboratories, Inc. Emergency Telephone Number: 706-343-6060
1000 Seachem Drive Telephone Number for Information: 706-343-6060
Madison, GA 30650 Date Prepared: 26 June 2006
SECTION II: CHEMICAL INGREDIENTS/IDENTITY INFORMATION
Components:
Proprietary aqueous
solution of complexed
hydrosulfite salts.

[Sapperdaddy]

NH3 is a gas, so when it is in aqueous solution, it is NH4+ already. It sounds like jargon stating that it is converted. 
I would think that if the fish were removed from the system the effect would last forever. However, if they keep adding ammonia eventually the equilibrium will shift back towards levels dangerous to fish. Your nitrifying bacteria are the only things that neutralize the ammonia. So I would say both groups are right, in reference to your original post.

[Borek]

NH3 is a gas, so when it is in aqueous solution, it is NH4+ already.

No. Ratio of concentrations [NH₃]/[NH₄⁺] is a function of pH:

[tex]\frac {[NH_4^+]}{[NH_3]} = 10^{9.25-pH}[/tex]

As water in aquarium is typically close to neutral or slightly below, most of the ammonia is protonated, but if the pH goes up, that's no longer true.

[Irlanur]

why don't you just test it? that's the only way you can really know it, the rest is speculation (or educated guesses)