The gunk in the probe happens, glad you got it sorted out as you found out a pH reading that far off reacts on the plant negatively. Your new growth looks great you’re safe to cut off the crispy leaves now. 
The root cause of a majority of problems is pH imbalances in my experience. I clean and calibrate my Grobo pH probe each grow.
Also to piggyback off what Azuri said, ph pens are an integral part of the grow as you have experienced. I would further caution, the use of a cheap ph pen will confuse you more than help you. Always choose the highest quality you can afford when it comes to ph and ppm/ec meters. I recommend nothing less than blue labs!! Never had a problem, and can sleep well at night knowing they gave me accurate readings 
I bit the bullet and got a blue labs kit 
She has been improving dramatic for the the week, until I notice some drooping and some browning on the tips at on Aug, 7th, 2019 (day 40). During my water change, I notice the EC probe was a little dirty (black gunk removed) so it was cleaned. Tested the EC of the water and it read a .3.
Just curious if EC meters usually get dirty on a day 40 grow and requires cleaning. Is this a common issue?
Just glad I got quality meters now to pin point issues. Just wished there was a dashboard giving us readings.
That rh needs to go waaay up. You need to be looking at like 70-80% at least. I think that will help a great deal. Plants “pores” need to be open to breathe and consume nutes. Keep her that low and ec keeps climbing you’ll experience nute lockout super fast. 
And man are there a lot of nutes used from every bottle, with such a small plant??? Somethings definitely up
I forgot about monitoring humidity since its been in the 50%, but it has gotten cooler here recently. Time to purchase another piece tool for the “automated grow box” 
@Osage Do you still recommend this model for the grobo?
https://www.amazon.com/TaoTronics-Humidifiers-Ultrasonic-Humidifier-Operation/dp/B07S59MHJ9/ref=gp_aw_ybh_a_8?_encoding=UTF8&refRID=WWN5AB4J5Q8YA7F49B7R&th=1
Yes that’s the one I have but in black
The charts you posted are cool and well known, but you don’t need to follow them to a t all the time. Think about what nature does and try and mimic that!
49 Total Days - Current Stage - Late Vegetation (Day 25/35)
@Stephen After the recipe adjust from yesterday, I think she is improving since the fan leaves are getting bigger and she is growing.
EC =.6 and pH = 6.5.
I am thinking about finally topping her since no more issues are popping up.
What do you guys think? OK to top or give her a few more days?
She is growing up to be very pretty! 
I’d let one more node appear then top 
She been growing well and there hasn’t been any more issues besides the grobo leaking. I was just wondering if she is ready to start transition stage? She been in late vegetation stage for the longest time (66 days)
.Late veg till she hits that second fan. Lookin good
((#ToppingTime)): 
((#ItIsTime)): 
((Yes)): You are correct, these are bud sights to be:
Top her, move the SCROG up to the bottom of the 2nd and keep adding veg time until she’s about 1-2 inches from the SCROG. Kick it to flower, weave, harvest, smoke.
I have 5 sites where it appears to be new sites growing. Are these where the cola will grow from or just from the main stem?
I have already top the main stem.
U could top the extra 4. I’d lollipop them as well to help the get as tall as main
