Now that you have pH understood, you are giving your plants the most opportunity to eat the ppms.
There’s isn’t an exact science to ppms. The theory is that if your water (or nute solution) going in has ppms of 200, and your runoff ppms of a 1000, then there is 800ppm of “stuff” in your medium. That “stuff” can be made up of nutrients that plant can use, other particles that don’t hurt the plant but provide it no value, and potentially harmful particles. Potentially, anything your plant doesn’t eat, plus the neutral and bad stuff, will build up in your soil. In addition to what is going in, the root interaction with nutrients also leaves behinds salts. At high ppm levels, all these good, neutral, and bad particles can all hurt the plant. All of this build-up can also impact the pH, too. The only way to remove the build up is to water to runoff such that they are carried out.
There are different philosophies on with the runoff should be, but there seems to be some consensus that you want it to increase as the plant matures. There’s lot of indication that having a runoff over 2000ppms is likely to start messing with pH and potentially causing lockout or nutrient burn/excess issues.
Some folks recommend flushing the plant periodically, especially in coco; and, also when you are transitioning from one nutrient type to another (veg/grow to flower/bloom for instance). I have only ever flushed for when the ppms got too high.
I have found that a sample of a the start of the runoff will differ in pH/ppm than a sample at the end. Try to be consistent in how you go about sampling runoff. There is no right and wrong - start, middle, end - you just want consistent sampling techniques. I am a middle-end-ish person.
I have been in veg phase recently, ppm-ing in around 400-500 and getting back from my plants 700-1100 for example. If that 700 becomes closer to the 400-500, that’s an indication my plants eating faster than I am feeding it and I need to ratchet up the food; if the 1100 starts to creep further up, that’s an indication of build up and I may want to consider flushing or lower my food.
Another caution is that ppms measurement is not necessarily an indicator you have all of what you need. Your ppms may be reading fine, but you could be running short of something like calcium and magnesium, which is common. So, even if your pH and ppms look aces, always be on the lookout for leaf symptoms.
@garrigan62 has a lot of great posts on ppms and ph. Here’s one that I like