A pH pen is going to make things a lot easier and a lot more accurate for you. The best way to check your pH is to do a slurry test: mix equal parts of DRY soil from near the root zone and distilled water (about an ounce or two each), stir well and let sit for 15-30 minutes before dipping your pH pen in for a reading. Adjust the pH of your nutrient solution to raise or lower the pH of the soil as needed. I’d also recommend using an EC/TDS/PPM meter to visualize the salt buildup in your soil so you can decide wether or not you need to flush. High PPM would indicate a flush might be necessary. Nectar For The Gods makes a liquid bonemeal (Herculean Harvest) that is great for flushing excess salts from your soil, and also liquid limestone and phosphoric acid (Olympus Up and Hades Down) that is good for pH adjustment.
Does anyone know of anything else, besides plain water, that is good for dealing with excess salts in your medium?
Link to a good pH pen and conductivity meter.
Get NFTG stuff here.