OP plz excuse this slight derail, but I think it needs to be posted.
@Jc1119, man you just might've accidentally saved my butt! I read that whole link you posted. and I "Just happened" to have some recharged larger-than-recommended-for-the-tanksizes Purigen bags (their first re-charge) from my smaller tanks. They were soaking in a water bucket, and GUESS WHAT? I tested the ph at 6.4, & my tap is 7.7- 7.8.
WHY doesn't Seachem recommend using a buffer that is closer to your tank ph YET?
Thank you for bothering to correct my post!
Is there already an mfk warning thread? Seachem should clarify this for small tanks.