PH malfunction, What to expect?

I accidently forgot to check my PH after I added nutes. After the nutes my PH was in the high 4.0, or low 5.0. I know this is a bit low. I was wondering if anyone had any advice? Also, what should I expect within the next 24 hrs.

It's only a week old seedling, can it survive so much acid?

I use RW by the way...