My hydroponic solution PH keeps rising to 7 and TDS drops

i am starting a DWC system with top feeder and a bubbler (i heard it might be called bubble ponics)
the problem i am having is my PH will not stay between 5.5 and 6.5 and i don’t want to keep adding PH down to keep it in the recommended range, below is an accurate detail of what i did and how long i waited between steps

first day of set up i filled reservoir with fresh water and started air pump and let it set for 24 hours, second day i started the water pump and let it circulate and i checked my PH and found it at 7.2 i then used PH down from General hydroponic and lowered it to the PH 5.8 and added my nutes, i then rechecked the PH and the TDS it was at 5.8 and TDS was 318, i did not add any plants yet but i waited to allow the water and nutes mix for 8 hours and then i checked my PH again and found it had climbed up to around 6.4 and TDS was down to 278 so i decided to wait to add a plant until the next day. the next morning I checked the PH again and found it at 6.9 i added a plant to the system and 2 days later (today) i checked the PH and found it at 7.2 how do you keep the PH to stay at 5.8 as recomended

ph down is so helpful, but the correct one… not citric acid… and increasing nutrients should lower ph. :grinning:

Phosphoric acid.


add your nutes THEN adjust your ph. I never mix in my reservoir, mix it in a seperate container and make ur adjustments and let it sit for 20, 30 minutes b4 u add it to your reservoir,

i still dont understand what is phosphoric acid and when to use it, i see Kettle has made a reply to this topic am supposed to use phosphoric acid where kettle has mentioned “not citric acid” and i am going to assume Kettle means to use it instead of PH down or is it used in conjunction with PH down,

please think of me as a school kid and put a little depth into it ( actually i am
a retired Senior citizen trying to learn new things)

not only is this my first time growing but it is also my first time for the Bubbleponincs or any kind of ponics,
i know i am biting off more than i should
and i really appreciate the help,

i am using this first grow as a training tool,

i started with some just average street weed for my practice run and plan on growing some good stuff as i bought 3 kinds of good stuff seed from ILGM,

this practice run has already helped me in obtaining the proper equipment, i started in crawl space moved to home made tent and then a quality grow tent,

i can see the improvement with each upgrade in the grow environment, now i am working on third upgrade in lighting BTW i am doing hydroponic and soil as back up in this practice in case hydroponic turns into a giant fail lol


@frankiefingers no worries, we all started somewhere. I’ll post an amazon link to what I was referring to, and I’ll explain a little farther. Brb.

thank you this sounds like a very good idea, i will get another container just for this purpose, does the temperature of the water effect the readings? so far i have been letting water set 24 hours to come to room temp before doing anything and I have the room temp set to 75°F

Temperatures do affect ph, but not a large enough difference to matter. You can use the same container with all the nutrients, but just mix a small amount in at a time, shake well, then check again. Don’t forget to tag me @Covertgrower if you have more questions. I do try to check all the threads, but don’t want yours to become buried.

This is a diluted form of phosphoric acid. I recommend this product for beginners because it’s diluted, you have to add a little more.

General Hydroponics pH Down - 8 Oz

It’s usually more affordable from a hydroponic shop, but you may not be in a legal state with shops available.
This solution takes 5-6 DROPS to bring the ph down, depending on the hardness do your nutrient solution and water.

Phosphoric Acid (80+%), 960 mL (32 fl. oz), HDPE Bottle


Thank you so much will get this item I already have the PH down from GH it worked but
over a 36 - 48 hour period
the PH came back to where i started at,

i seen you in an earlier topic i had yesterday and i have a new question about that LED light topic so i will return to that thread and ask my question, the question is actually directed to bulldognuts and nicky but i will try to tag you in it in case you have a good answer you would like to share

Tag me anytime! @frankiefingers

GH uses this in their PH down.

When adding nutes/changing rez first use the correct nutrient line for the water used. Some are buffered for 250 ppm tap water (FF) and some are buffered for distilled/R/O (GH). Never mix products.

If your PH rises (and it often will some), keep adding down until it remains in range. It might take a couple of days. Usually though I can mix my nutes and it’s sitting at 5.8 and stays there for 2 weeks.

1 Like

Remeber that large grows will have ph dosers that automatically monitor the ph as the plants metabolize the food and eventually alter the solution. The sensor tells the doser to raise or lower the ph. So to will be your situation as your plants consume nutrients and use water. Eventually the ph will need to be adjusted. Depending on your setup, like dutch buckets, I put a clear drain hose through a rubber grommet into the bottom of my buckets. The hose is long enough to act as both ansight glass to see the water level, and a drain to either change my solution or test it. I tested evey morning or if a problem showed up. So get used monitoring both the ph and EC fairly regularly especially in a dutch bucket with no reservoir…

If you ran system with no plants were the lids off ? Or just open net pots?
Light getting in can change ph.
Or you adjusted ph in the reservoir and it simply rose as it mixed with the rest of the water. Or you used tap water that didn’t sit 24hrs and still had chlorine in it, that burns out and changes ph a bit. Always check all pails. Or as suggested mix and ph water and then pour it in system. Repeat until system is full.

Also read nutrient directions. Some say to ph water first then add nutrients. And specific order needed as well. Ah the fun stuff. I remember when I didn’t know that much…oh snap I still dont know much. I sure love growing !!!

hey thanks for helping

yes i mixed in the rez,
i let the tap water set 24 hours with the air pump running,

i had 2 water pumps circulating the 10 gallons of water at 500 GPH flow rate while mixing the added PH down from GH i let it mix for 5 mins or maybe longer between adding and testing and yes i used tap water i was able to get the ph down to 5.8 over a 30 min period i then added the nutes and i used GH flora series and yes i had the empty net pots hanging in the holes

is it safe to keep lowering the PH every day? and today i added a second air stone

i only have 3 holes for plants and i added one plant to it immediately after testing levels and being satisfied of the levels and had 2 empty net pots hanging in the other 2 holes,

BTW i was so impressed at the growth over last two days i have added 2 more plants today filling all three wholes

hello frankie, glad your here, sorry if I was short… id just used citric acid for months and since I have changed to phosphoric acid and potassium hydroxide it has been stable…

you are going to need your nutrient temp to be kept cool and use a product to protect the roots… most use hydroguard, there are other things that can cause your ph to rise…

but keeping the nutrints cool is important…

can you take some photos and give us a bit of a tour… :smiley:

i actually took some pics this morning of the roots starting to emerge from the net pots i am attaching them now, i will take pics of a photo tour later this evening when i return from my DR appointment i have scheduled, i am supper impressed on how fast the plants are developing because the plants i installed just day befor yesterday approximatly 36 hrs ago have roots starting to grom out of the net pots and the plants have grown so fast it has me completly amazed after this practice run is complete i may switch all my plants over to the hydroponics for all my future grows, pic 3429 is oldest by 2 days pics 3428 and 3430 are installed just 36 hours ago i will give complete tour later this evening


I was reading this thread and wanted to say that I hope your grow went well and I wanted to mention that I am using the same totes with the yellow lids like in your pictures but if you havent already addressed this issue, those yellow lids let in tons of light if you dont cover them with something. Light leaks are a big deal for lots of reasons so if you havent, completely cover the tops with something, preferably reflective. I used white duct tape and taped down the net pots and all. Also cover the net pots completely with paper plates(or something equivalent with a hole and slit for the stem since light gets down in there through your medium and roots hate, hate, hate light and algae and bacteria love it.