P.H readings and Dissolved Oxygen

[Hawzzy]

Here's the situation.....ive heard and read about increases in oxygen raising PH.
I have a home made bubble cloner/veg chamber. I adjust the PH of the light nutrient soloution then leave it alone with a big airstone.
Every time I check the P.H...its very high....I add a little ph down....check again its good...a couple hours goes by...check it and its high again.
Is it ACTUALLY RAISING the PH.....or is a false reading....I use drops AND my pen when im unsure.

 

[since1991]

And it will. Say your solution ph is 6.8. You drop it to 5.8 with ph down. Put an airstone in there hooked to a pump and aerate it overnight. Check it 24 hrs later....back to 6.8. Phosphoric acid dissipates with high amounts of dissolved oxygen.

 

[since1991]

Be careful adding ph down constantly to keep ph in a target range.

 

[mandy1]

hey there hawzzy- some nutrients are more ph stable in dwc. i use reverse osmosis water and the ionic line of nutes. very reasonable and ph stable

 

[Skunk Baxter]

I always swap out reservoirs after the last feeding of the day, then put an airstone in and let it bubble 24 hours or so. Then the next night, I pull the airstone, add my nutes to the water, set the PH, and leave the airstone out until the next res change - usually about 3 or 4 days. I try to oxygenate the water as much as possible before adding the nutes, and then once they're in, no more air.

Life is a never-ending series of compromises...

 

[Hawzzy]

Thanks for the input friends...im using a beneficial bacteria tea to help keep the slime away.... another compromise I guess...I dont want to use bleach or h202 on or in my plants nutrient solution. Ive always wndered if it really dissipated the acids used to lower the ph or if the increased DO just gave a false reading.

 

[rkymtnman]

I adjust the PH of the light nutrient

a stronger solution will be more pH stable. i've noticed that when starting seeds/seedlings where my EC is only 0.2 to 0.3

 

[since1991]

Thanks for the input friends...im using a beneficial bacteria tea to help keep the slime away.... another compromise I guess...I dont want to use bleach or h202 on or in my plants nutrient solution. Ive always wndered if it really dissipated the acids used to lower the ph or if the increased DO just gave a false reading.

No false readings....its rite. The phosphpric acid is reacting (dissipating) because of the air being pumped into the solution. Raises ph everytime.

 

[Hawzzy]

Good point. It is with my newly rooted clones I a lower solution thats giving most issues. The last nute change Im up to 400ppm from 250 ish....ill see today if its at least a little more stable....
I putin a monster airstone....maybe I should scale it down a bit. I often read about people puttin in more and more airatones cuz their roots love it....how does it not screw with the ph.
The other thing is....in my main bucket...10 gallons...I just had to scale the nutes back from 700 to mid 500 ppm to avoid tip burn.

 

[Hawzzy]

="since1991, post: 12405841, member: 909944"]No false readings....its rite. The phosphpric acid is reacting (dissipating) because of the air being pumped into the solution. Raises ph everytime.

Pain In the ass eh?

 

[since1991]

Drop it to 5.6 initially. Let it rise with the airstone and your start water hardness (assuming your not using ro water) naturally. Dont keep adding ph down in an attempt to combat this. Your plants should do fine. Ionic grow amd bloom with a horticultural grade hydrogen peroxide (oxy plus) is perfect for dwc and is all you need.

 

[Hawzzy]

Im using town tap water...I leave it out for multiple days...it starts at about 70 ppm. Not too bad. I changed the airstone to a much smaller one...I dont want em growing too fast...im only 3wks into flower in my other cabinet lol. Im aiming to double and split my flowering area in 2...one side 4 to 4.5 wks ahead of the other...harvest every month and a bit. Ill watch the little ones closely for any signs...and try to keep the ph down to a minimum.

 

[rkymtnman]

here would be an interesting test. buy a really small water pump, some tubing and elbows for it and build a really small waterfall in your res and see if it interferes with pH as much as airstones.

i switched out all my airstones for waterfalls a few grows ago.

 

[Budley Doright]

I thought the rising PH had to do with driving out CO2 in the water with the addition of DO, I have found this to be very confusing lol. I am just happy not to have to fuck with them anymore and PH. seems quite stable but yes I do need a shit load of down at each refill, pretty sure well water has some pretty good buffers.

 

[Hawzzy]

This is my first foray out of soil...live and learn...try or die I guess. In my 10 gal 2 plant bucket...with 5 gal res...I have 6 tubes...2 in each net pot and two just spraying into the bucket. It rises much more slowly. If I run rdwc again...I will incorporate a waterfall or fluming from a small pump...or build it in somewhere.
Im thinking about trying aero with organic nutes next run though.

 

[rkymtnman]

I thought the rising PH had to do with driving out CO2 in the water with the addition of DO, I have found this to be very confusing lol. I am just happy not to have to fuck with them anymore and PH. seems quite stable but yes I do need a shit load of down at each refill, pretty sure well water has some pretty good buffers.

how much is a shitload? i use about 3 to 4 mL pH down for a 15 gal res. how much you use?

 

[rkymtnman]

Im thinking about trying aero with organic nutes next run though.

not an aero expert, but you might want to rethink that. all your sprayers will be clogged in no time.

 

[Budley Doright]

how much is a shitload? i use about 3 to 4 mL pH down for a 15 gal res. how much you use?

35-40 ml per 25 gallons

 

[Budley Doright]

This is my first foray out of soil...live and learn...try or die I guess. In my 10 gal 2 plant bucket...with 5 gal res...I have 6 tubes...2 in each net pot and two just spraying into the bucket. It rises much more slowly. If I run rdwc again...I will incorporate a waterfall or fluming from a small pump...or build it in somewhere.
Im thinking about trying aero with organic nutes next run though.

I just ditched the sprayers and went back to flood and drain totes.

 

[Hawzzy]

I fell in love with the idea of rdwc for my first foray into hydro...BUT it takes SOOOOOOO much nutrients. Each bucket takes a few gallons...plus the res takes even more gallons. Even though you can keep the ppms down....the sheer volume of nutrient solution is insane.....plus you need crazy water movement OR air stones which as we know causes problems of their own.