adding nutrients only to my tap i get a ph of 6.6 , i still would have to lower with citric acid to get optmal ph of 6.

In case you didn't know there is a Hydroponics forum here and likely your best source of info on questions such as this. It is such a different method of growing compared to dirt gardening that few of us here can be helpful.

Dave

Here is a link that might be useful: Hydroponics forum

Ia addition to the hydroponics forum there are numerous threads on acidifying water, and bicarbonates, in the Fruits forum. This is just one example:

Here is a link that might be useful: acidifying water

Add your nutrients then adjust ph to where you want it.

When i add any nutes to my soil grows i always adjust my ph to between 6.4 - 6.8 this is the range my plants do the best.