Why does the PH in my water go up overnight?

[Nept64]

My plants were beautiful. I hooked up an auto watering system because I would be gone for a week. I got home, checked my plants and they had a lot of yellow/dead leaves and all the leaf tips were yellow.
When I collect my water the PH is about 8. I bring it down to about 6.5 to water my plants and have no problems. I watered last night, brought the water down to 6.5PH. I checked the water that was left in my bucket this morning and it was up to 7.7. What would cause it to rise? is this normal?
I have a 10 gallon bucket with an aquarium heater set at 80 degrees, an air stone to keep the water moving/add oxygen and I keep it covered.

[DabberDog]

Air stoning raises pH.
80° is pretty toasty for plants.
Are you in soil or coco?
What are you using to adjust pH?

[Rwise]

And is it city water, well water, river water, rain water etc.?

[DabberDog]

Bridge over those troubled waters.

[dirtymike]

i will lay me down in the water

[Wayzee]

Turn the aquarium heater down to 70 would be where I start.
if your using a pump to auto water and there is a gap between where the water comes out hose or drippers and before it goes onto your medium your oxygenating the water pretty well anyway and you could do without the air stone.
Also is it just water or did you add nutes?

[Nept64]

I was wondering about the airstone....
my tent is 80 degrees so i thought the water should be the same.
i use well water and bypass the softner.
I use ph down (orange bottle) to lower the ph. I usually use a watering can but tried the pump when i went away for a week.
growing in living soil so no nutes.

[Wayzee]

I also remember air stones usually increase the water temp as well unless your air pump is in a refrigerator.
How far along are the plants? Living soil has a life span, then you have to add some form of nutes and microbes to "rejuvenate"
Another thought, did you do trial run with the pump to see if it would be watering the same amount as you do by hand?

[DabberDog]

Lose the heater.
Prep your nutrient solution before adding it to your reservoir. Pay attention to how much pH down you use when comparing stoned water to unstoned water.

[golfnrl]

The answers above are spot on.

The need for an auto watering system led me to Autopots. I tried a DIY system with a reservoir, check valve and drippers. That worked for a one off because I found there was no way to control the PH.

Autopots are a gravity fed self-wicking bottom feeding system. The plants take what they need when they need or want it. I don't top water. And there is never any overwatering. The best mediums for autopots are a 50/50 blend of perlite and soil or coco. Clay pebbles can also be used instead of the perlite. I use a BlueLabs PH controller to keep the PH steady in the rez. Depending on the stage of growth i can be away from my plants for about a week with this system.

Let us know how you proceed. I might learn something.

[Nept64]

i will take the suggestions and figure it out. thank you everyone. :-)
i thought living soil was all you needed (first time trying living soil). I'm growing autos in 5 gallon fabric pots. they are 6 weeks old and 4 feet tall. (gorilla glue). i will keep an eye out for nutrient problems.ty

[golfnrl]

I thought the very same thing about living soil when I first used it. My first grow with with FF OF blend soil. The plants used up the nutrients but I was too inexperienced to know what was going on. Learned about that later. I switched to coco. I'm a bit OCD and feel better when I know exactly what my plants are getting. The coco lets me do that.

[Smallgrow]

Like everything else in growing, “living soil” is variable. For it to be water only you need enough nutrient rich soil , probably not smaller than a 10 gallon pot for a tent sized plant, maybe more.
Also genetics, environment, watering, have an impact on what the plant needs. Most people I think are amending along the way to some degree, it’s likely you will have to in 5 gallon pots. See if your soil manufacturer has an amendment pack or bloom amendment. You didnt say what brand you were using, but using another living soil brands amendment should be fine too. I would suggest using something premade rather than individual amendments.

[dirtymike]

If your autos are 4 feet tall from the medium at 6 weeks she might be stretching a we bit, eh.... Where's me pipe.

[Nept64]

they did stretch a lot but they are filling in nice. :-)

[DabberDog]

What does the living soil manufacturer say about pH'ing their product?
Have you checked the pH of the runoff?
Got my own curiosity going and scanned a few things. Theoretically, you don't need to pH living soil. But to be on the safe side, do it.

[Nept64]

I get no runoff on my living soil to check. i read you don't want runoff because it with flush the nutrients out of the soil. i give them a half gallon of water every 3 days and they are very happy.

[DabberDog]

Picturess?

[dirtymike]

Damn it jim

[Wayzee]

I'm using similar to living soil, says water only on the bag but my girls have been in it for 5 weeks and I've already given them 2 doses of nitrogen+ cal-mag, a dose of seaweed and a dose of microbes and a auto that I've twice fed seaweed, amino acids and potash. I can see the difference the potash has made and have had no burn. I also been following Nebulas watering schedule and avoiding runoff, I use rainwater so I don't have to adjust pH as yet.

[Allotrope1000]

Lots of factors will affect the pH of your water or nutrient solutions - temperature swings, source water chemistry, products you intentionally dissolve, etc. Also, time setting around pre-mixed in a bucket. All the dissolved ions are constantly inter-reacting trying to obtain an equilibrium state in your solutions.
The faster you use your solution after mixing gives it less time to change pH.
Given the above, I noticed my pH's rising over time spent sitting to be used. It is easy to check pH with your meter or test strips. You might originally adjust your solutions down to pH 5.5-5.7 and let climb up to 6.5 ish before lowering again. That pH swing of about one point covers the optimum range for various nutrient uptake.

I run 12 AF plants in 50/50 coco/perlite in 7gal fabric pots in a polytunnel greenhouse during the winter months.

[Allenpro]

The lesson in all this is dont setup an automated system and walk away without observing it for a while, like the week before you leave. Hindsite of course but been there done that

[Allenpro]

I think I get it now, hydro growers are monitoring the PH of the media (water in the reservoir) 24/7 . With soil you cant do that as easily because the water/nute mix can change when its added to the soil so thats why you do the "slurry" to find out what the media PH level is at. Is that about right? Did this blind hog stumble upon an acorn?

I never understood checking runoff PH before, it always reminded me of an how an old farmer checked to see if the cows were getting enough salt.

[Wayzee]

Yep and the soil pH can slowly build up over time if the water you're using has slightly high pH especially if you're not watering to the point of run off.
Haha that just reminds me of the 2 weeks work I done at a dairy farm... Yea na not for me, thanks for the opportunity though. Hahaha

[Allenpro]

The only time I want to see a cow is on the butchers counter

[dirtymike]

hence the numerous salt blocks next to the watering trough.