Seachem is noted for heavy use of borate salts in many of it's products, really something to watch out for. Be sure you are doing weekly water changes to keep elements in the water from becoming skewed.
I've never been a fan of using buffers to control pH. More commonly it ends up working against you and the pH eventually crashes without warning. If an emergency, that's one thing but day to day control is not recommended.
Check the alkalinity of your tank and your new SW
along with the pH. If the alk
is not in the 2.75-3.0 mEq/l range, you should buffer some to increase it but that will only help with pH stability, not maintain the level. If the alk
is already in that range, your problem is not chemical, it's environmental. pH is is controled/affected by the level of CO2
and acids within the tank. If alk
is good, then the problem is most likely CO2
related. Use of solid lids without a good sized sump, lack of total water movement throughout the tank as well as the surface, insufficient air flow in the tank room itself (open a window) as well as improperly running gas appliances.