help with ph fluxuation in my resi

ok i know the ph can change rapidly in a reservoir. but has anyone ever heard of the ph not moving much when putting in the ph up/down?
i have a 10gal resi with a single pump and a single air stone rite where the intake is for the pump. i calibrated my ph meter prior to checking resi. when i checked the resi it was like 2.8 or something real low...never seen it this low. then i put in (advanced nutrients)ph up, like 5mils. mixed the water around and checked the ph. it didnt move much, but normally with 5mils it would change mor than it did this time. so i repeated the process a few times and i seriously had to ask myself why isnt it going up much and something told me to stop putting the concentrated ph up in.
the 1st time i noticed this i had tried something to make taking care of all my stuff a lil easier. instead of pulling out every resi, every time the water level reached the pump (low), then bringing em to the tub and cleaning out the old water/neuts and scrubbing the resi, then replacing with new water/neuts. i tried adding fresh water/neuts and checking the ph when the water level got low. (I dont know if that's a good idea or not but i figured id try it, then wash it out like normally once a month or less)
so i thought this was my problem with my ph not really going up when i was putting plenty of the ph up/down. so i cleaned the resi out and put fresh water/neuts and it did it the very next day! i was pissed cause this has never really been and issue. sometimes i wouldnt check the ph for 2 days and it would be a lil higher. id set it at 5.8 and 2 days later it would be like 6.5 but never 2.something a day later.....
please help i just put fresh neuts in and dont wanna dump the water/neuts daily too expensive and time consuming.

what is the temp. of your res,and also are you adding the ph up and down to the res or are you adding it to some water and then putting it in the res,and are you giving it time to work, I add it to some water and put it in then I wait a half hour or so and then check it,but your saying the ph was at 5.8 and the next day it was 2 point something thats a big drop if thats what you mean,wich may mean problems,I grow dwc in large coolers I keep my res at an average of 65 with lots of air(8-6" airstones per cooler)and GH nutes and some florablend,and koolbloom and my ph stays at 5.8 and I only do 1 res. change while in flower,and 1 during veg and 1 time during the clone process,also I dont mean to be a smart ass but are your batterys good I bought some cheap button type batterys that were no good and also I have a ph meter that gets wierd readings if I check it where theres bubbles in the res.

Whats your TDS from the tap? Are you using RO? Your "fluctuations" may be due to the buffering capacity of the water. [FONT=Times New Roman,Times]Buffering capacity is the ability of a solution to resist changes in pH. Obviously, [/FONT]pH that is too low (under 5) might result in micronutrient toxicities and damage to the plant's root system.

Like snocat said, add your pH down mixed with water. Add a little bit at time until you get your desired pH. I find it may take 2-3 days to stabilize pH, as many factors influence it. (TDS, Cl2 etc).

Do your nutes have pH control? Are they 2 or 3 part? How are you mixing them?

snocat said:

what is the temp. of your res,and also are you adding the ph up and down to the res or are you adding it to some water and then putting it in the res,and are you giving it time to work, I add it to some water and put it in then I wait a half hour or so and then check it,but your saying the ph was at 5.8 and the next day it was 2 point something thats a big drop if thats what you mean,wich may mean problems,I grow dwc in large coolers I keep my res at an average of 65 with lots of air(8-6" airstones per cooler)and GH nutes and some florablend,and koolbloom and my ph stays at 5.8 and I only do 1 res. change while in flower,and 1 during veg and 1 time during the clone process,also I dont mean to be a smart ass but are your batterys good I bought some cheap button type batterys that were no good and also I have a ph meter that gets wierd readings if I check it where theres bubbles in the res.

Click to expand...

resi temps in veg rite now are 76-78 degrees F and the bloom resi temps are 74-75 degrees F and ive always added it directly to the water and stir it around and check the ph a few mins after. ill check batteries for sure. ok i was kinda wondering on the meter itself...its my 2nd one in a year hanna i believe the red one

Rube Goldberg said:

Whats your TDS from the tap? Are you using RO? Your "fluctuations" may be due to the buffering capacity of the water. [FONT=Times New Roman,Times]Buffering capacity is the ability of a solution to resist changes in pH. Obviously, [/FONT]pH that is too low (under 5) might result in micronutrient toxicities and damage to the plant's root system.

Like snocat said, add your pH down mixed with water. Add a little bit at time until you get your desired pH. I find it may take 2-3 days to stabilize pH, as many factors influence it. (TDS, Cl2 etc).


Do your nutes have pH control? Are they 2 or 3 part? How are you mixing them?

Click to expand...

tds from the tap is 200-300ppm, and no RO system yet. im using botannicare rite now and i use a bottle that i put a lil bit of water in and then put the measured neuts inside and then shake it up prior to putting it in the resi with all the tap water. not sure if they r ph control or not..
thanx guys

When you have high ppm tapwater it usually contains a lot of carbonates, calcium and such from limescale. This has a naturally high buffering capacity. My tap is as bad or worse than yours and I find it takes several ph down treatments to get it stable. I have to start using RO. 18 gallons of water took nearly half a small bottle of ph down!

thanx everybody