I dont think the fish drops are the best idea...

PH is critical when growing cannabis, wether hydro or soil. A proper PH test kit with up and down is crucial. Also a PH pen is much better than test strips or color drop testing...

When you begin to mix nutes up it will discolor the water and be impossible to take accurate readings via color drops. If you arent adjusting your water then it most likely is too high if its tap. Light coloration with dark veins can be attributed to PH imbalance.

You can get a cheap milwaukee ph pen on ebay for $20 or less. GH ph up and down you can get in a bundle also for cheap.