My frogs have always done well on the lower side of ph,usually around 6.8.I personally don't feel safe when it comes to the ph increasers.I had one bad experience using it with Apple snails,and have been to chicken to ever try it again.Any time that I need the ph increased,I always use the crushed shells in a filter,but with the Eclipse filters,there's really not a space to do it.
Most sites I've checked out mention ph averages for these guys to be anywhere from 6.4-to 7.Honestly,I don't know the effects that a ph of 6 would bring for them.Alot of animals can adjust to ph's,it's the bouncing up and down that hurts them more.
Some people also test their water out of the tap,let it sit 24 hours and retest,only to find that it's raised up a bit.This area of knowledge though isn't my strong point,so I won't even try to explain the how's and why's..

Maybe you can do that ,just to see if the level changes.It's good to know all you can .
With all the ph increaser's,are you maintaining stability,or are you constantly dealing with ups and downs ?
I think though for now at least,you should see some improvement when you get the ammonia/Nitrites down to 0.Have you noticed any change at all since you did that last water change?
As for the eggs,-are the plants new?Were they quarrantined/treated before adding them to the tank?ANy signs of snails up until now-actual snail s/chewed plant leaves,etc.?
Did you hear any croaking or see any signs of mating before the eggs showed up?
I've known people who's frogs have mated,but none of them had any successful hatches.ALthough I've seen the mating behavior myself,I've never seen any eggs being released,or eggs stuck anywhere,so I don't know if they'd look like wild frog eggs or not.Can you post a pic?