i believe sensible opinions of the small tank with e yellows not being suitable is lost now firenzenz.
as for making the conditions suitable for them in their apartment, in my experience ph is not a major factor in their well being or breeding abilty as long as it is in the 7's or higher & is stable. i had mine in around 7.3 or so IIRC & they did very well, i have arogonite with shell pieces as a substrate which raised the tap ph slightly. i am currently on tank water, concrete tanks with a ph of around 7 which raises to around 7.2 or so in the tank with the substrate & the tangs also do well. as long as the ph is stable & not too far from their wild requirements they will adjust, if you start messing with it & it swings you are going to have big issues.