High Ammonia?

[Fred37]

Hi Folks,

have been performing weekly 20% water changes on my Dad's tank and yesterdays was undertaken on schedule. I always do a water test first.....using a Tetra 6 in 1 strip test (the results of which were all in the green) and a JBL ammonia test.
I was a bit shocked when the ammonia test reading came back with a 5.0 reading!! Whilst we don't usually get a zero reading we do normally come up at about 0.05 and so this was a bit of a surprise.
So my question is two-fold:

1) Any ideas as to what could cause such a dramatic shift in readings when all the other measurements are OK?
2) We have been using Ammo Lock to try and get the 0.05 reading down to 0 per advice received from users of this site and so is it possible that my JBL test kit is reading the total ammonia in the tank and not just the total 'bad' ammonia as I understand that Ammo Lock changes the constitution of the ammonia into a 'harmless' form although of course it is still in the tank?

My Dad has a 64l tank with 16 fish in it (1 algae eater; 1 cherry barb; 2 neon tetras; 2 harlequins; 3 zebras; 3 plattys; 2 mollies and 2 guppies).
Any advice gratefully received.
Thanks,
Fred.

P.S. His balloon molly died yesterday.

 

[Fred37]

Forgot to mention, that I did a 50% water change yesterday.
Fred.

 

[WILDER]

Test strip cards are not accurate.
Is the jbl a liquid ammonia test,.
Plec are massive waste producers so how often does your dad do a water change and gravel vac.
Does he over feed.

 

[Fred37]

Test strip cards are not accurate.
Is the jbl a liquid ammonia test,.
Plec are massive waste producers so how often does your dad do a water change and gravel vac.
Does he over feed.

Yep, the JBL is a 3 part liquid based test.
'scuse my ignorance but it's a chinese algae eater....so is that still a plec?
We do 20-25% water changes every week.
Filter pads are rinsed out every week in ex-tank water.
The new water is always treated correctly and Stress Zyme is also added weekly.
He was feeding daily based on the "...enough to be eaten in a couple of minutes" instruction, but I've persuaded him to go to every other day.
Regards,
Fred.

 

[WILDER]

For some reason I just call them plecs when there cat fish lol.

I would maybe post this thread in tropical discussion as ammo lock can give false readings I think. No nothing about the product as never used it.