Yes, I was wondering about the method of dosing for two 2.5 tanks and wanted to make sure things were going the way they should. When you said ten I was hoping they were both in there.
As BFM said, the meds break down, and this may be what's causing the slow progress. They're getting a full dose when you first mix it up, but by the next day the meds that were premixed in the 10 have lost their strength and efficacy.
I had a 5 gallon hospital and it was a pain, with the two meds being packaged for a ten gallon. I poured mine out on card stock and with a credit card I separated the pile into two lines, like you see cocaine being done in the movies or on TV. It's not precise, but it's close.
When I had my lines looking equal, I'd scrape one line into the tank, carefully so as not to disturb the other line, then I'd fold the card stock and pour the other line into the tinfoil packet. I kept the other dose closed up in the foil and in a ziploc as BFM did.
I think things may turn around if you start dosing this way. You really must put fresh meds in their tanks everyday, just after the water change. Don't feel bad, it's an easy mistake to make. There's nothing on the packaging that mentions the meds becoming unavailable, or ineffective, after a few hours if mixed in water.
The fish get the benefit of the antibiotic right after it's put in their tank and for a few hours, but not many. I've read comments by others that state after 12 hours the antibiotics have broken down and are unavailable.
Don't let this discourage you, just do the dose tomorrow using new packets.
EDIT: Or dose this evening if the dose they already got today was the premixed water from yesterday.