Its worse than i thought...how much Prime?

[bleed water]

Hi all,
this is an update on an earlier post which went on and on, but long story short(er), I'm in a mini cycle from taking out the filter media when medicating the tank for mild fin rot. This is the third or fourth day of pwc's with prime and I'm hoping it can get over with soon without fish dying. I'm worried the prospects may not be looking good based on my test results.

Yesterday's readings were .5 ammonia, .25 nitrite, 15 nitrate so i did a substantial water change. I awoke today to 4 ppm ammonia and 0 nitrite. Did a 50% water change and it's down to .25-.50. How much prime should i put in there? I know It says you can use up to 5 times the regular dosage for a nitrite emergency. I have a 20 gallon tank so if the "normal" recommended dosage is 2 drops /gallon, then I can add 100 drops when I do a 50% change? How often or for how long can you do that? I haven't been adding nearly that much but maybe should start. I've read that at 4ppm you will almost certainly see fish gasping and dying but then also these may be readings of detoxified ammonia from the Prime, like false positives essentially. It is so confusing! I'm thinking it's the latter, but still -- that's HIGH.

At any rate the fish are not gasping, they're actually chasing each other and still interested in mating but that's pretty much the status quo with my cherry barbs. Actually one alpha male does most of the chasing and the females tease. I'm very attached to these guys... I hope they're gonna be okay.

 

[Coyne]

That's confusing. You had 4ppm ammonia, you did a 50% PWC, and afterwards you had .5ppm ammonia?
You see the problem with the math here, right?

 

[bleed water]

Right. Well I was going on the assumption that when you first add the Prime to detoxify, the readings come down initially...that it reads as if you didn't have ammonia in the tank at all, or much less. Then later today I read that Prime can give you false positive readings so that's just the opposite. Honestly I don't know what to think and that's why I'm here. If I could count on things being like I'd expect them to, based on the numbers, it would all be simpler. Obviously something isn't showing the "accurate" amount but seeing the tube come out bright crayola green is really disconcerting.

 

[Coyne]

The Prime converts the ammonia into a less toxic substance. I'm not really sure of the chemistry involved.
It shouldn't have any effect in the ammonia test though. Assuming the test is valid, those are the readings you should go by. When I was doing my cycle, it was suggested I wait an hour or so after PWC to do any tests. Give the old water and new water the chance to mix and balance out.

 

[bleed water]

Ok thanks, I'll wait a while longer before checking next time.