PH probs -DWC -

Hey guys i've started my first DWC everything running great but everyday i adjust the ph to 5.8, and every morning its back at 7.0. My plant is suffering.
Am I doing something wrong? Is there anything I can do to stop it from going back up so high and fast?

Thanks so much boys

What's the temp of the water in your res?

I've had some problems with rising pH which was from the temp in the res being too high and root-rot setting in. Check to make sure your roots are bright white and your temps stay bellow 70F!

Good luck

I have yet to see any concrete example of pH being affected by temperature. Oxygen and carbon dioxide content can definitely affect pH (high O2 saturation drives it up, high CO2 saturation drives it down), but are transitory as the water's levels of O2 and CO2 are always in transition.

What you're experiencing is called pH bounce, and this is a result of the source water's alkalinity (buffering capacity). You will need to find a way to buffer the water down. One cheap way is to filter through peat moss. One less cheap way is to find products to add. I like SeaChem's product lines, they're very high quality. Look for something like their Discus Buffer.

pH rebound occurs when the carbonate hardness is high.

The primary cause of high pH is an elevated carbonate hardness (KH) level. Carbonate hardness, also known as alkalinity, is found in tap water.

This phenomenon may be because the water company is adding buffers to keep pH in a certain range. We "thought" that we were having this problem, but discovered that our "rebound effect" was linked to a certain fertilizer we were using.

fertilizers often have a significant effect on pH. Very few fertilizers are neural pH. Even different fertilizers within the same brand line will have different pH. Often the fertilizer will have buffering agents that can resist pH correction. So, it is extremely important to test all of your fertilizer and additives to see if they are causing hidden changes in your pH level

Hard water has lots of minerals and is typically very alkaline. Our water is about pH 8.0


Even if your water starts out acid, many water companies add chemical to make it alkaline (acid water can leach unhealthy metals from pipes). In some cases, your tap water quality may shift through the year: our water company uses rain runoff water in winter and spring, but shifts to well water later in the season. Your water company may have a web page or an information number that you can call to find out more details about your tap water.


Some water companies are replacing chlorine with chloramine. Chlorine evaporates quickly from the water, while chloramines lingers. Water companies use chloramine to insure a constant level of chlorine in the water. Unfortunately, this product can accumulate in soils and there have been reports that some violets are particularly sensitive to it. Pet or aquarium supply store sell chemicals to correct this problem if you think it is an issue.


Water softeners DO NOT remove minerals from hard water. They perform an exchange in which salt ions replace the mineral ions. The result is softened water that has salt in it. This is important to know because plants do not like salt and it may cause problems for them.


Reverse osmosis is a way of creating "pure water." Much of the water that you buy in the store or from vending machines is simply tap water that has been purified through reverse osmosis. This water is very similar to distilled water… that is to say it has minimal minerals. This may be good, or bad in some circumstances. For AV growing, reverse osmosis water is mostly good since it is neutral pH. If you have hard water, you may notice that mineral salts build up in the soil (particularly during hot dry summers). Since RO water has essentially no minerals, it corrects the problem of mineral salt build up.

From:Water pH Goose Gardens Gardening Supplies

Great post, but, technically, R/O is filtration, not purification. One thing to remember is that you end up with a good deal of waste water. Thusly, the suggestion to simply filter through peat, or not worry about it since it's an even 7 right out of the tap.

Carbonate hardness is but one method/type of hardness and measurement. Water municipalities are switching from chlorine to chloramine not because of stability issues, but because of breakdown products being associated with cancer. Sodium thiosulfate breaks that chlorine + ammonia bond that comprises chloramine.

I just found an interesting site. Alkalinity Tables

Great post!
Thanks man!
I am using tap water, with a 1/4 hydro grow nute, rockwool and net pots over an 8L res. I let the water stand for 24+ hours before I use it. The roots and very white and healthy looking.
Do you think it would be better to try and correct chloramine with chems or just buy distiled water?

if you can get a bigger res or pot/bucket then you will be less vunerable to PH bounces too.

dunno if that helps

yea but its such a pain to change the water. I thought about half full with a drip system, but I have enough trouble keeping the water cool without a pump in the res.
I'm using a 3 stage cycle, clones/veg/flowering. 2 plants per stage. 3L res for clones/seedlings, 8L for veg, and 25L for flowering (holds 2 plants).
Is bottle water better then tap? Like those huge 20L water cooler jugs?
Where would I get distiled water?

Bigger reservoir isn't going to change the root of the problem--the source water's alkalinity. I don't know where to buy distilled water, and frankly, I don't like using it for living organisms because it's JUST water, and most.. no, all organisms I've kept need some of those minerals that are in the water. Reverse osmosis should do you alright.

But, before you go worrying about that pH and alkalinity, here's a question: How are the plants doing? If they're doing alright, then why mess with it if it ain't broke, ya know?

She (I fuckin pray to god she is after I ended up with 9/9 males with my WW) is showing signs of phosphorus deficiency caused by high PH. (According to the marijuana horticulture indoor/outdoor medical growers bible)

I adjusted the PH to 5.2 last night and this morning its 6.0, They look alot healthier.. i'm just hoping it not on its way back to 7.0+

The worst part is, its just bag seed so i don't know the strain. I kinda just want to scrap them but i can't get more WWxMango seeds for another week and half and i feel like i'd be wasting time with an empty grow room.

How did you end up with 9/9 males of WW?

Bullethead21 said:

How did you end up with 9/9 males of WW?

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I had 9 white widow x mango and they all were male. I know the odds are crazy but thats how she goes I guess.

really pissed me off.

Thinkin i should just buy fem seeds.

i use tap water as well
do you let it sit for 24hrs before using it?

HydroBandits said:

i use tap water as well
do you let it sit for 24hrs before using it?

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I have a 19.9L res that i let sit for about 4-5 days between rez changes. I pour out the water I need, 1/4 grow nute, adjust it, and scrub/refill rez.
Maybe putting too much o2 in the water? Maybe its Cloramine?

I doubt it. Do you know what chloramine is? How it's removed? Did you understand the bit about alkalinity we posted?

Seriously, if what you want is easy pH buffered down, SeaChem. Google them. I can vouch for their quality (even though ya don't know me) products and consistency.

Seamaiden said:

I doubt it. Do you know what chloramine is? How it's removed? Did you understand the bit about alkalinity we posted?

Seriously, if what you want is easy pH buffered down, SeaChem. Google them. I can vouch for their quality (even though ya don't know me) products and consistency.

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Yea I read everything very carefully and did some more reaserch.
I've read that its best to use destilled water. I still have time before I can get better seeds, trying to move over to hydro, so just soaking in as much as I can

Hey everybody, not sure if this is the right place to say this, but I'm having my ph drop steadily fast. I just recently tried the Seachem line of Alk buffer. Seems to brought me up. Small small grow with a tall girl who is LST TO THE MAX LOL to save her from burning. Anyway, is buffering the same as using Ph up from GH?

Stoner87 said:

Hey guys i've started my first DWC everything running great but everyday i adjust the ph to 5.8, and every morning its back at 7.0. My plant is suffering.
Am I doing something wrong? Is there anything I can do to stop it from going back up so high and fast?

Thanks so much boys

Click to expand...

Newb here, just started. Same issue, studied and studied all i can find, but you just can only fix ignorance. I have to learn the hard way just like every soul on here! Vinegar is not the cure all for me anyhow, Tap water, ph 8. Vinegar down to 5.5 - 6. 3 hours later, back up to 7.5. Noticed a white gummy substance, cloudy water after about 5 days. I just ordered PH Down. I call my new room "The Lab" and just keep experimenting. Thanks for all your suggestions to everyones growing passion!

Are you measuring your ppm? As ppm drops in your res. and plants are taking up nutes and that will usually raise the ph. Maybe you plants are just eating lots? If they are eating lots add more nutes. May help your ph issue.

Turpman said:

Are you measuring your ppm? As ppm drops in your res. and plants are taking up nutes and that will usually raise the ph. Maybe you plants are just eating lots? If they are eating lots add more nutes. May help your ph issue.

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^This is spot on. Your plants are using the nutrients and your pH is rising. That indicates your plants require more nutrients.

You definitely want to completely change your res out every week. This is very important because we don't know which nutrients the plant took the most of and by refilling the res with nutrients will lead to a buildup of some nutrients and a deficiency of others.

It's like going to McDonald's and getting a burgers and fries. Some days you pound the burger and pick at the fries other days you mow the fries down. It's best to start each week with a fresh burger and fries so to speak.