It won't hurt to throwing the borax across the pool, but.... make it easy on yourself. Just pour it in the skimmer. That is what the rest of us do. Since you do it while the pump is running, it immediately is pulled into the filter, dissolved, and quickly out into the water. It doesn't just sit in the filter. If you have any big clumps when you pour it into the skimmer, just reach in and break them up. Within seconds it is mixing in with your pool's volume. Nothing to be concerned about!