@orbo I have a ppm meter just never used it. I'm using rodi water and I veged for almost 2 months. As far as nutrients go for I'm only using the 3 parts big bloom, grow big and Tiger bloom. Here are some pics of the leafs I took off their the bottom leaves. In the fox farm line I'm guessing tiger bloom is the flowering part, grow big is veg and cal and mag is big bloom? Correct me if I'm wrong. I'm sorry ahead of time if it's a stupid question but in a noob trying to lean.
No sorrys, we all start somewhere. Its all good.
RO/DI ya say. Well then you definitely need Cal/Mag supplement. The yellowing in the pic is almost surely Cal/Mag deficiency and will continue to get worse until you start adding some.
Grow Big = veg
Tiger
Bloom = flower
Big
Bloom = flower
( see how that works?)
Cal/Mag is none of these three. Its not listed in the chart, its just something we as growers know needs added. MJ uses quite a bit of Cal and Mag ESPECIALLY during the transition from veg to bloom which explains why its just showing up now, because you went thru this transition a few weeks ago.
Since you are just learning to understand and use the PPM meter your take aways for this lesson are these;
Step 1 - Use the PPM meter to get your water baseline. In other words, get a gallon container, fill it with rodi water and check PPM. This is your baseline - your starting point. I will take a guess and say your rodi water is 20 PPM. That would be your baseline.
Step 2 - After you getting some Cal/Mag, add enough Cal/Mag to the water to make it 170 PPM. Optional - Consider bumping up the Cal/Mag a little since its showing deficient.
Step 3 - If it were me, I would probably split the other nutes up like this -100 PPM Big Bloom/50 PPM Tiger Bloom/50 PPM Gro Big for the first feeding. Of course if your girls respond positively then I would keep bumping up these 3 nutes as the weeks go on.
This is where you pause and give pHed water with some Cal/Mag for 2 waterings and watch the girls to see how they respond to the nutes you gave them. Pay particular attention to the very tips of the leaves. If nothing NEGATIVE happens then start upping the nutes each feeding.