What I am seeing is falling water, so the plant is drinking. The TDS is staying pretty static, but that is after the water loss. Once I refill the rez to level, the TDS is then lower.
So lower TDS and higher pH. Could it be that the plants are just feeding heavy?
I do see a little tip burn so I have been reluctant to raise the TDS.
There is a chart somewhere that shows pH and EC changes and what it means the plant is doing.
For example EC drops and pH rises, then the plant is taking more nutrients than water. EC rises and pH drops, the plant is taking more water than nutrients.
Your pH ramp sounds spot on from my research. I’ve never grown in DWC. Have done a couple F&D grows.
Edit: this post had that chart
Very helpful discussion, thx to all participants!
I’m posting that chart on my grow room wall. 
Atually I have another question.
Am I not observing sound practice by using TDS and PPM as my variables, vs EC. I do see a lot folks using the EC metric. But conductivity and ppm have a fixed & direct relationship I believe.
In my head they are just different metrics for the same characteristic. I have done a lot of various water measurements, boiler water, fish tanks, etc… In those I always used TDS.
In other words, is there any reason to use one column vs another in the chart below? I use the last column.
Atually, me too! Since we have the A-Team checking in.
What is the tool of choice for TDS & pH continuous monitoring?
I ran a water chemistry lab for awhile and all of our flow through probes were a headaches, needy little bitches with constant buffering, cleaning and calibration. Is that still the current state of the art for pH instrumentation?
Looking for specific purchase recs here, willing to spend a bit more to get a lot more convenience and reliability.
The problem with PPM/TDS values is you have no idea what scale is being talked about. They all work by measuring EC. So if I say 1000 PPM, you won’t know if I mean 1.4 or 2.0 EC without telling me the scale.
@GrouchyOldMan , and all others, let me go on record.
I take no offense, and indeed greatly appreciate input from any and all in my threads. I consider any in depth discussion on relevant topics to be of great interest.
So by all means please jump in. The only thing I ask is lets keep a high bar for the factual.
I had terrible pH swings when I was running distilled water. I switched to city water that came out of the pipe at 250 ppm and it solved my pH swings immediately.
I have used a lot of inline monitors for pH and TDS. Mostly in maintaining very large African Chiclid ecosystems.
I found most pH system to be temperamental, I cant recommend any beyond the expensive industrial models.
For TDS I highly recommend the HM Digital brand of instruments. I have used them for about 20 years now and I trust them. The probe fits inline in a Tee in your supply line from your rez. Africans Chiclids like a high TDS but evaporation raises the TDS. So I used one of these to automatically trigger an unattended water change until the TDS was back in range. Worked to roughly a 5% water change every day.
https://hmdigital.com/product/cic-152-n-cic-152-4/
This was my last aquarium, a lot of things in our DWC world are very similar in principle.
You really gotta love fish to set all that up and maintain it…
Thats awesome
Day 37:
DLI: 40
My pH swings finally settled out, I think I might have gotten the ratio of the 3 nutes out of whack. Now it doing great, pH stays stable and water level and TDS both dropping over time. Started bumping up the nutes.
This was yesterday morning
This was last night
One of the 2 big plants showed me some tiny balls and got chopped, and I think the other big one is going to be a male too. That leaves me with the 2 small ones that I hope are girls.
Yeah I know I am a rookie, but damn that hurt!
Really makes me think hard about doing Regs when I have to observe a 4 plant limit.
If you do go the female seeds route just do some research on the breeder. It seems some are more known for herms then others, personally I love female seeds.
Glad you go things back on track those blue lab guardians are sweet.
Thiis is what it looks like this morning.
Had to chop the biggest plant, tiny little balls taunting me.
I have not seen any pistols yet, but these last 2 smaller plants now have a lot more room to spread out.
Had to adjust the nutes, and lower the lights, a bit as the 2 big feeders are now gone.
Curious side note. The stumps from where I cut them are still pumping water. The cut face of the stump is steady dripping.
Yeah, the Blue Lab gear looks like good value @MrWizard for a dual function pH & EC system. Are you happy with yours?
I bought a APERA Instruments PH20 pen/kit today to solve my immediate needs. Seems like the bottom end of top end gear and it only does pH, so I’m still looking for a long term solution.
Final thoughts before we let you get back to your grow log @MrWizard? LoL and thx for hosting this discussion.
-Grouchy 
@GrouchyOldMan yes, I am happy so far. Although I have not seen how long the probes last. Replacement pH probes are about $70 I think.
What I have always seen in pH applications is that it is the probes that will go first. If I get 6 months to a year out of the probe I will be happy.
I have seen several others complain about LED segments going out on the display. Have not seen that yet, but then it has only been in service about 40 days.
That being said, I am now spoiled and will always use a realtime monitor. My old bones arent so crazy about bending over 15 times while you adjust pH and then check it again a few times to ensure its stable.
Roger That Mr Wiz. Old bones: one of the things that actually makes me Grouchy these days! PITA not being able to do the stuff I could do a few short years ago…
Keep us in the loop on Blue Lab as you gain experience. I may just be able to steer my Saintly Spouse in that direction for my Xmas gift!
I have had my eye on this guy for awhile. Milwaukee generally makes decent stuff but I don’t know anyone that uses this.
Milwaukee Instruments MC720 Dosing Pump Kit
Hells Yeah, @CosmoNut, that Milwaukee design, pH sensor AND microdosing adjustment is the complete package. $250 for the complete package?
Crikey mate, I’m researching further… 
Nice Find Brother,
-Grouchy
