which buffer to use?

[Cunningham]

hi i was just wondering what kind if any i should use?
ive had a saltwater tank for a couple years now and up until a few months ago i was using treated tap water and i was also adding supplements and everything else the petstore told me to buy and then u guys all told me get ridda the chemicals and get ro/di water so i switched over to ro/di water and i haven't added anything but the water and salt and my tank is doin awesome now.... its never bin better all my corals and fish r healthy and look great....but i noticed today my pH was a bit low at 7.8 and i know in the morning its usually lower than at night but i don't think it should be this low? or is it nothing to worry about? ive bin tryin to keep away from chemicals but if theres something i should be using that works good please let me know thanks
-Dan

 

[rush]

7.8 PH is fine

The generally accepted pH level in a basic saltwater system is between 7.6 and 8.4, but reef tanks are a bit more sensitive, and therefore need to be kept at the higher end of the pH scale, 8.0 to 8.4.