Had the same problem with the Red Sea syringes. I painted the graduation markings with clear nail polish. Be careful on the first coat as it may slightly smear the lines. So far working great.

5ml syringes don't have enough markings on them. You need .1ml accuracy. Also the pink dispensing tips only fit a certain type of syringes.

I've found a local source to try some higher quality syringes. If they work I'll order a box.

I'm gonna use a similar technique once I get a new set. Either clear polish, clear tape or one of those clear screen protectors that's adhesive backed.