rise or lower the Ph

[Saludos]

Amigo Ron:
I just started with my 25, two-liter-bottle garden and I had a hell of a time trying to come up with the right amount of fertilizer and so on. My system works with a sumergable pump (2100 lt/hr) and the reservoir has an 80 lt capacity and I'm using triple 14 as fertilizer and 80 cc of folial fertilizer, too. The Ph level was too high and I used hydrogen peroxide (9% v) to make it go down to about 6.8.
What I would like to know, besides the rigth proportions of fertilizer, is what products can I use to rise or lower the Ph without ruinnig the plants and ,of course, the fertilizer mixture? Can I use the same products people use to adjust the Ph in swimming pools? If so, I will appreciate a list of what i can and cannot used and the amounts in grams, please.
Thank you and best regards
Saludos
Julian Pena D Venezuela