DWC pH drop with healthy roots?

I'm running a one plant cooler dwc with a res of about 4 gal. Definitely light tight.

Lucas Formula 8:16 at ppm~820 (I use RO water); res temp 65-69ºF.

My pH keeps dropping and I'm not sure why. I've been keeping it in check with some pH up but I'm wondering whats going on....

I've looked around but can't seem to diagnose.

-->My roots look/feel healthy and are growing, as is the plant, and I dont see any other problems yet, other than this drop in pH so whats going on?

+rep for any help thanks guys

Have you changed your nute recipe or anything else recently? To me it sounds like it could be a number of things, like nute buffers or maybe even something going on with your RO filter. I think your going to have to look at everything your doing individually if it continues to be a problem. Also how is the humidity in your room? Also can you check your ppms in your res before you top off when your checking your PH?
KnB

my ph drops when its time to change my res.maybe I should rephrase that,when my ph starts droping I change my res. usually I get around 2 weeks before I have to do a res change but I have a large res and that helps with getting a little more time between changes good luck

The smaller the body of water, the more erratic it could be...

I wouldn't say anything is wrong per se... especially if your plant looks good. Ph drift just comes with ther territory sometimes. Again, if the plant looks healthy, don't look for problems that aren't there.

My ph rises the first 36-48 hours after a res change. It levels out during the mid-week and starts to fall slowly as res change time approaches. Of course this will vary depending on strain/nute.

Dwcnoob: not knowing what strain you're growing, if you don't have an algae bloom going on in your reservoir, it sounds like you have the same problem I did with my last grow. Previously, I grew with a couple of Aerogardens and I grow bag seed I've reproduced for about the last 27 years; a mix of Sativa and Indica. When I switched to two ten gallons DWC's my pH went down instead of up, (the opposite of what I was used to). I consulted the guys and gals here, the people I trust at the hydro store and a couple of instructors I've had at the college.

One guy at the hydro store suggested that having my rack of T-5's one inch off my plants might be the culprit but it never has been in the past. Another suggested root rot, which it wasn't, and after scrubbing my reservoirs and changing the nutes it continued. Finally one of the teachers asked how my plants and roots looked? When I said good, he said correct the pH back to 5.8, and quit worrying. (He knows what I'm growing), so I didn't have to BS him and he was right. I just harvested my crop, cured it and sampled it and it was as good as anything I've ever grown. I would advise you to do the same thing he told me, "Keep your reservoir clean, your pH in specs and quit stressing. Enjoy the process. You'll just use a lot more pH up instead of down." HSA

snocat said:

my ph drops when its time to change my res.maybe I should rephrase that,when my ph starts droping I change my res. usually I get around 2 weeks before I have to do a res change but I have a large res and that helps with getting a little more time between changes good luck

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Probably this.. Have you changed or cleaned your res.

HSA said:

"Keep your reservoir clean, your pH in specs and quit stressing. Enjoy the process. You'll just use a lot more pH up instead of down." HSA

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+rep for everyone who replied, sorry I keep forgetting that I'm not auto-subbed to the posts that I start--I thought no one had replied.

I just changed the res because I'm switching to flower today, but I think I'll go with HSA's advice. Everything looks good, I'll just use more pH up....

BTW if anyone wants to pop in and check out my girl, I'm growing a mendo purps clone and its my very first grow.

Pics from last night. 30 days since I brought her home

dwcnoob said:

BTW if anyone wants to pop in and check out my girl, I'm growing a mendo purps clone and its my very first grow.

Pics from last night. 30 days since I brought her home

View attachment 1848598View attachment 1848600View attachment 1848601View attachment 1848602

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Lookin' good. Hey, my ph is dropping too.