strange observation of pH drift half-way through flower cycle.

[gmskunk]

Currently at day 59 (Flowering - Day 32) -- here's my journal

Genetics: White Widow

Nutes: Advanced Nutrients Bloom A+B + CalMag and a dash of epsom salt

Issue: Since the very beginning (and even during the previous cycle), the pH of my reservoirs has always drifted up and each day (sometimes 2x) I would have to use pH down to bring the level back to 5.4ish. This past weekend, I started noticing that White Widows reservoir pH has been moving lower and lower...down to 4.4 over a 24 hr span. I just replaced the nute solution this past Friday (after 2 days of flushing) at a strength of ~700ppm. Yesterday, I topped off the reservoir with another gallon of R/O water and reset the pH to 5.4...the nute strength is down to 650ppm. This morning the pH was back down to 4.5.

I'm going to flush and refill shortly, but this is a very very odd reversal in a decent pH trend. I was under the impression that pH should always rise as an indication that the nute solution is being absorbed. Are my plants vomitting up nute solution? Doesn't appear so when i check the TDS reading...

 

[Cannabinoid]

Yes it is very odd that your Ph is decreasing....
Couple of things you may have missed:
1. Have you re-calibrated your Ph meter?
2. Where is your reservoir, and is it getting to hot where your reservoir is? One other thing I would look for is if you are having to fill the reservoir more now because of heat = evaporation.
3. What is the standard Ph of your water? Always make sure to Ph the water BEFORE mixing the nutes.

BTW: I looked at your journal. Your plants look great, definitely not vomiting anything.

 

[hashhead]

i have the same thing happen to me.ill fil my tanks with r/o water and set the ph to 6.0 (im in veg still) and after 8 10 hours the ph starts to drop.i read somewhere on here u can add tap water to stablize it but i dont see how that would work?

 

[hashhead]

btw im useing the same shit to lower my ph and useing that type of ph down seems it doesnt to stay at correct ph readings for long period of time.

 

[gmskunk]

Yes it is very odd that your Ph is decreasing....
Couple of things you may have missed:
1. Have you re-calibrated your Ph meter?
2. Where is your reservoir, and is it getting to hot where your reservoir is? One other thing I would look for is if you are having to fill the reservoir more now because of heat = evaporation.
3. What is the standard Ph of your water? Always make sure to Ph the water BEFORE mixing the nutes.

BTW: I looked at your journal. Your plants look great, definitely not vomiting anything.

1. yes...twice in the past 2 weeks. Also, the reservoir for my other plant (NorthernLights) is reading correctly and behaves according to past trend...pH level increases with time.

2. the reservoir with the decreasing pH (WhiteWidow) sits closest to the AC intake...so the reservoir is definitely not warmer than the other (NorthernLights). Furthermore, Whitewidow is about 25% larger than the NorthernLights and the reservoir level doesn't decrease faster than the Northernlights...meaning I don't think the WhiteWidow's reservoir is having anymore evaporation than the NorthernLight's reservoir.

3. I use R/O water so I believe it is pH neutral. I have always pH'd the reservoir after adding nutes. A typical reservoir change consists of me removing the plant, airstones, and pump...dumping the old solution...cleaning the reservoir...adding the R/O water...adding nutes...pH the solution...add pump, airstones, plant.


I'm not too worried...as long as the plants don't start to look problematic...I'll just need to start targeting the top end of the pH range for this plant.

 

[gmskunk]

btw im useing the same shit to lower my ph and useing that type of ph down seems it doesnt to stay at correct ph readings for long period of time.

my understanding is that pH rising is a good and expected thing because...

Say the water out of your faucet is at a pH level of 7. Since a lot of (most?) commercial nutes are designed to lower pH, when you add them to your water you may see the pH drop to 5.8 (depending on the strength you are mixing at...if you add more nutes, your pH may drop to 5.6 - just depends...always good to have a meter ). Now over the course of the week as your plant drinks up those nutrients, you will see the pH level rise as a result of there being less pH-lowering nutrient in your solution.

this could be total bullshit... but I am certain that I did read it somewhere on this board over the past year...

 

[hashhead]

damn we must have read the same article lol. but i dont feel good abut useing tap water theres tons of crap in the water that arent good for your girls.if u dont have a r/o filters i would go for distilled water.

hey guys anyone ever try the water u can get from free spring water you can get off the mountian

 

[McBudz]

Excess buildup of sludge in the lines of that setup that may leading to the down shift?

 

[Sensibowl]

I'm with the others about not using tap water. It's higher in pH than you want it to be, making it too difficult to control once you start adding nutes and other things to your plants.

Of course, it's also cheap.

You could also leave some tap water out overnight to let the chlorine gas that's pumped into it escape. Those bubbles that you see in the water the next day? That's the chlorine gas leaving the water — a real threat to your pH levels.

Maybe try that with your water first before going to another source.

I like to keep things cheap, if possible.

Always keep the bowl full...

 

[WarBux79]

I am experiencing this same issue using advanced nutes. My TDS levels are rising and PH is falling. It seems to me the plant is taking more water up and that is causing the nute levels to raise which in turn is lowering the PH