PH after adding Nutes (Canna- Bio Flores)

Preface: first grow, soil, 7 plants none older than 1. month. just put them under a 400hps. been feeding them tap water (PH 7+) until yesterday.

Yesterday: went to hydro store to get nutes. ended up being sold BioCanna's bio flores and cannazym. AS WELL AS A PH KIT. After flushing all my plants with 6.0ph water i still wanted to add these nutes lastly. Side note: is this stuff any good? he steered me away from FoxFarm on the grounds of it being synthetic.

HOWEVER, When adjusting the PH after adding nutes how do you tell what color the water is turning when its shit brown. I thought the indicator made it turn reddish (more acidic) does this sound correct.

It's hard to see "Yellowish-Greene" thru brown.

Thanks in advance. I am really enjoying this new hobby,

I know this may be a bit late.. like 3 years late... but i just read this post... so here i go...
Canna bio flores corrects the ph solution to 6.5 for you... you do not need to correct the ph everytime u use the bio flores or vega ...
If you wanna do your plants more good.. u could just add some humic acid to optimize the plants feeding at a wider ph range...