any ideas on what would cause one reservoir (non recirculating) ph to drop?

Okay, I mix my nutes about every 3 days. GH flora micro/bloom with 50 ppm tap water. In the rez are two pumps, one for circulation, the other feeds a wand. Both are always on.

Sitting right beside it is my flowering res. Practically the same, except micro is usually a bit lower.

They are less than 6 inches apart. The flowering res ph stays perfect for 3 days, but the veg res drops hard, usually around 4.8 by day 3. (my last watering)

I bought a new res, gonna swap em out, but before I did I thought id ask if anyone had any clues what could be causing it?

Temps are 68-ish in the res, no plant matter etc ever gets in it. Kept in dark, yada yada. Im assuming its some kinda bacterial thing maybe?

One thing to watch out for depending on how big your roots are is to make sure water is flowing through the roots. One week I couldn't figure out why my ph kept diving fast... turns out the rootballs were so thick they were just holding old low ph water and shit inside because I wasn't mixing well enough or getting any flow through the roots.

Your case may very well be pathogens or something else... but I just wanted to throw that out there cuz it happened to me, and I never see the suggestion that the root ball could be holding old water like a sponge.

I have ideas, but the non-recirculating part is stumping me. So you're feeding drin to waste, so the nutes that go to the plants never come back to the res. So the plants aren't changing it... You could be losing water to evap, which could lower ph as the nutes concentrate. That's a big drop though, to be just evap. Although... 50ppm tap is pretty clean and soft. With very little buffers in it the ph could very well swing wildly very easily.

Hmmmm.....

Mithrandir420 said:

I have ideas, but the non-recirculating part is stumping me. So you're feeding drin to waste, so the nutes that go to the plants never come back to the res. So the plants aren't changing it... You could be losing water to evap, which could lower ph as the nutes concentrate. That's a big drop though, to be just evap. Although... 50ppm tap is pretty clean and soft. With very little buffers in it the ph could very well swing wildly very easily.

Hmmmm.....

Click to expand...

ya, its got me stumped, like you say, drain to waste. And the other res using same nutes sitting right beside it is fine. Gonna swap the res out tonight and see if it fixes it. (cleaning pumps etc before putting in new res

So this is the second night on the new res, ph hasn't budged. Assuming it was something dying in the res. Hopefully no more issues (normally ph would be a low 5 by now)