yellow leaf tips

issues of fertilization don't happen overnight unless you did something incredibly wrong. So a flush won't resolve anything if you don't correct the imbalance of rate of provision vs rate of use. It's piling up over a long period of time if the formula is good. the longer it took to turn into a toxicity means a smaller adjustment is needed to the formula. Leaves look too dark, so too much N is a possibility.. so is too much Mg and another thing or two. These symptoms are not discrete. Since it also looks a bit glossy, i'd lean N-tox related. Burnt tips are soemthing different and also caused by several things. P/K/S all potential issues. A leaf chart is very useful. Tracking how you feed over time is also helpful in diagnosing the problems seen. You need to cross reference more information than just what the leaves tell you or it amounts to a guess in most situations. The pH swing is probably a bit bigger than you want, but neither 6.2 or 6.5 will lock things out. You may see some wavy growth from the days this fluctuated but if pH remains fairly steady going forward, then that won't continue. it affects rate of growth so you get some leaves that might grow a bit funky. So, i'd adjust the product with most N and least impact on other parts of nutrient balance - drop it 10% and see how it goes. If darkness continues to increase, drop it further. If toxicities start to cause real damage, another flush might be necessary. Reserve flushing for extreme situations. it's rough on the plant.