I have a 10 gallon with all of the fish in the signature except for betta (he is in a bowl).
Yes, the lady used the liquid test tube things, but she didn't say any numbers.
She told me to take out 1/4 the water once a week (refill of course), put in this 'Stress Zyme' stuff, and clean out gravel once a month.
You know, the problem is that the people who work at petco are just people looking for a job, and they are not very experienced, since it is a (pretty much) nationwide company. City Zoo has people that are professionals. For example, if you were trying to decide which product is right for your problem, the people at Petco would just pick up the item, and read on the back what the differences are. I can do that myself! The people at City Zoo actually have experience with the items and fish. Petco also has all their fish tanks on one big filtration system, so if one fish gets infected, all of them do. City zoo has all the fish in total separate tanks!