Crazy PH swing

I am currently about 5 weeklst since germed and I finally got my ph meter. I've hit up all plants with nutes the last 3 waterings. I watered today just with water. Before watering just water and cal-mag ph was about 7.0 - 7.3. My runoff was 4.9 - 5.4. This seems very extreme swing and the reason of my concern is new bud sights seem a little twisting and possibly a little lighter green compared to the rest of the leaves. I'm using OF and Botanicare grow/liquid Carma and cal mag. They are in 5 gallon buckets and I wanted to start floating next week. I did adjust the ph meter prior to measuring what is eveyones input. Should I flush and then induce flowering to be safe? Any input is always appreciated they are also lst'd.

Do you check the pH of the nutrient solution before you water

Yes, sorry for not clarifying that when i checked the ph before watering it was with the cal-mag in it already. This is the first time i checked the ph as i just received my ph meter.

I still don't get why people test the run off. Grew dirt for years without evertesting it and shit comes out greeeeeeat

because in my old place i use to live in the ph was 8.4 and well would need it to drop the ph to normal levels.

So does the run off mean nothing? I always thought that u should always measure what's going in and what's coming out I am no pro by any means just thought that these figures were very wierd and drastic the last thing I want is to switch to flower and have a lockout right away and my by size suffer because of it