Should I just use water on my next fill up?
just halve or say 2/3rds (say 30mls per10l) of what you putting in there now, thats if you cant afford a ppm meter att, and how do you balance the ph get the cheapo ph dye kit and some ph up n down, i dont see those bottles in the photo
you also need to know the ppm or ec of the water you using (Tap or rain?) it plays a big part in balancing ph and getting correct ec for stage of growth. i tell folks to first ph and ec test their plain water, then get a permenant marker and add each nute to water
separately noticing if it has a ph up or down effect on the original water tested, then on each bottle write up or down, so you know... oh, this A n B bloom reduces ph, oh this pk 13.14 raises ph, seaweed additives = ph up, mpk = ph down etc etc...
Then as you do each grow you will be able to balance ph perfectly with minimal use of ph up or down acids
i havent needed ph up or down for couple years now, so just get the dye first and see if you can get it balanced around 5.5-6.0
you need a bluelab truncheon as well