[Myka]

Not sure what's going on with your test kits. Is the Elos brand new? Maybe it's a faulty batch. I'd email them.

Personally, I don't use any buffers that directly alter the pH. Too dangerous in my opinion. I use SeaChem Reef Buffer it only adjusts the alkalinity. Since pH and alkalinity are related, the buffer will alter the pH indirectly, unlike the ones that "buffer to pH 8.3".

I use Salifert for testing pH, or a Pinpoint pH monitor. All test kits are notoriously inaccurate for pH. Although they are close enough for what we need them to do.