Your readings were: Nitrites zero, ammonia zero, Kh3 , Gh >10 and Ph between 6.8-7.2. The tap water params are also the same except nitrates here are zero.
baking soda should work fine. I think part of the problem is trying to keep water happy with 3 goldies in the 5 gallon tank. Not much leeway there. It should be easier when you get the larger tank cycled. How much does it hold?
I've never used any other buffers cept for oyster shell. I don't know much about phosphate buffers.
I couldn't tell what's in the easy balance from their info on the web. A lot of it sounds like snake oil if you ask me.
Here's a FAQ on proper pH.
http://www.aquariumpharm.com/articles/propPH.aspIs says: PROPER pH 6.5, 7.0, and 7.5 are phosphate buffers
It also says that phosphate buffers make plants. unhappy
This FAQ on te krib says phosphate buffers can cause algae blooms.
http://faq.thekrib.com/begin-chem.htmlHere's an intersting page that's worth a read on pH and buffering.
http://www.malawicichlidhomepage.com/aquai...alawi_temp.htmlLook under the temperature table. Apparently some phospates increase pH and some decrease it.
Maybe someone else has used phosphate buffers and can tell you if they'll work better in your situation.