DWC PH issues - Ph dropping like a rock - Please help

Thread starter #1
Good morning folks,

I am having some PH issues with my DWC and I really need someone with experience / knowledge to help me understand what the hell is going on.

My DWC consists of a 10-gallon tub filled with 5 gallons of water. This DWC is supporting a single plant that has been growing strong for 12 weeks now. I just flipped the lights to flower yesterday.

It seems that on a DAILY basis, my PH drops at least 1 to 1.5 full points and I'm having to add 1.5 to 3.0 MLs of PH-Up to the reservoir to get my PH back into an acceptable range. My water level does not drop that fast and my PPMs are staying stable.

For example, not 20 hours ago, I took the following readings from my plant environment:

- Air Temp: 64
- Water Temp: 62.7
- Humidity: 32%
- Water PH: 6.0
- Water PPM: 590

This morning, I took the same readings:

- Air Temp: 63
- Water Temp: 62.5
- Humidity: 30%
- Water PH: 4.8
- Water PPM: 590

I had to add 3.0 MLs of PH-Up to get my reservoir PH back up to 6.1. My water level did not drop overnight and my PPMs remained the same at 590. I've been using 10ml of Hydroguard with every reservoir change and my roots look fine & bright. The water smells fine and there does not appear to be any signs of root rot.

I've attached my feeding schedule and as I just flipped to flower yesterday, I changed my reservoir and followed the "Week 6 - Transition" nutrient levels at 1/3 strength.

Can someone please help me understand why my PH is dropping like this on a daily basis?

PLEASE HELP.

 

Rifleman

Plant of the Month - November 2015 Member of the M
Also how are you measuring your pH ? Calibrated lately ? Batteries fresh enough ?
 
Thread starter #5
Thanks for the chart, @Rifleman. I found that earlier in my search for answers.

I have Blue Lab PH and PPM meters, both purchased recently. I calibrate the PH meter weekly using GH calibration fluids (4.01 and 7.0).

I've been reading a lot about the "Lucas Formula" and I'm wondering if it would do me any good to change my reservoir again today (5 gallons of water), going with the following:

40ml of GH Micro
80ml of Bloom
10 ml of HydroGuard

Thoughts?
 

Rifleman

Plant of the Month - November 2015 Member of the M
Thanks for the chart, @Rifleman. I found that earlier in my search for answers.

I have Blue Lab PH and PPM meters, both purchased recently. I calibrate the PH meter weekly using GH calibration fluids (4.01 and 7.0).

I've been reading a lot about the "Lucas Formula" and I'm wondering if it would do me any good to change my reservoir again today (5 gallons of water), going with the following:

40ml of GH Micro
80ml of Bloom
10 ml of HydroGuard

Thoughts?
I've got zero experience with Lucas Formula or the GH line. :sorry: I can only postulate what I might do in a similar situation. Which would be to compare what's different from the last stable point, what's my closest situation to the reference charts, what has changed since the last stable point, how drastic was the change, is there a mid point between here & there that might be worth trying, and when all else fails....reservoir change with a fresh mix, and a flush of my media.

Another thought though, do you give time for the chlorine to evaporate from your water ?
 
Thread starter #7
Another thought though, do you give time for the chlorine to evaporate from your water ?
I use RO purchased from the local supermarket, so I start with clean water (PPM = 0).

What I decided to do today was another complete reservoir change, PH'ing the water to 6.0 and cutting the nutrients further to 320 PPM. We'll see what happens overnight.
 

gr0w

New Member
I by no means am an expert. But that is pretty cold air temp for just switching into flower.
Try and maintain 65-80*F
When I switch to flower i maintain 78*F
Then by late bloom have the temp drop to 70*F.

Same with humidity high side of 40-50% when first switching then final weeks low side of that range.

I am too having problems with my pH dropping which I believe is due to room temp as my reservoir is not inside my grow tent.
 
Thread starter #9
Good morning, folks. I'm back with an update though I don't know if I'm any closer to a solution.

Yesterday, I did a reservoir change, cutting the nutrients by about half from the previous change. After several hours of bubbling away, I captured the following readings:

- Air Temp: 65
- Water Temp: 62.7
- Humidity: 32%
- Water PH: 6.1
- Water PPM: 350
- Water EC: .7

This morning, after the lights have been on for an hour or so, I captured today's readings:

- Air Temp: 64
- Water Temp: 62.6
- Humidity: 30%
- Water PH: 5.5
- Water PPM: 350
​​​​​​​- Water EC: .7

As noted, my PPMs did not change overnight. Also, the water level went down only slightly, maybe a 1/2 quart. That suggests to me that the plant is not drinking that much. Since the PPMs / EC didn't change, I guess that means that the plant is neither taking in nutrients now do I have nutrients leaching out of the roots into the reservoir. Yet my PH dropped significantly overnight from 6.1 to 5.5.

I just don't know what to think with the PH dropping like this on a daily basis. I live near a rather busy road so maybe I have elevated levels of CO2 in the air that are in-turn getting pumped into the reservoir where the molecules bond readily with my RO water. If that is the case, then I guess I have no choice but to drop 1.5 to 3.0 MLs of PH-Up into the reservoir each day in order to maintain PH in the proper range.

I think I'm am going to do another reservoir change today. I want to get my EC readings back up to around 1.2 (I am at .7 now). Since I just flipped to flower a day ago, I expect the stretch to commence and she'll be hungry.

Any thoughts? I really feel like I'm floundering here and need some guidance.
 

JD77

New Member
Hmmmm I am in mid week 3 of flowering and this morning I checked my res and I lost .7 PH last night. I run about 6.2 and was at a 5.5. That is a shocker to me because I have been steady throughout my entire grow. The only real difference was I finally turned on my gas furnace and my grow area is in that area. Had to be co2 pumped into the water.
 
Thread starter #11
I think @JD77 found the answer to my issue.

Yesterday, I did another reservoir change. I waited four hours or so before taking the following readings:

Air temp: 67
Water temp: 65.3
Humidity: 32%
PH: 5.8
PPM: 550

Today, about 16 hours later, I took the following readings:

PH: 4.8
PPM: 560

Water level in my 5-gallon reservoir dropped by about a pint.

When did this daily drop start happening? About a month or so ago, right about the time I turned on the gas furnace for the winter season. And where does my furnace sit? About 15 feet away from my grow cabinet.

So now I have to decide: Do I continue to use RO water, knowing that it sucks up CO2 like a sponge? I would have to continue to add 1.0 to 1.5 ML of PH-Up to the reservoir daily, not knowing how this might impact the plant. Or do I change to tap water, which would hopefully be more PH stable, not knowing what exactly is in the water to start with and having to deal with chlorine / chloramine?
 

JD77

New Member
Water level in my 5-gallon reservoir dropped by about a pint.

When did this daily drop start happening? About a month or so ago, right about the time I turned on the gas furnace for the winter season. And where does my furnace sit? About 15 feet away from my grow cabinet.

So now I have to decide: Do I continue to use RO water, knowing that it sucks up CO2 like a sponge? I would have to continue to add 1.0 to 1.5 ML of PH-Up to the reservoir daily, not knowing how this might impact the plant. Or do I change to tap water, which would hopefully be more PH stable, not knowing what exactly is in the water to start with and having to deal with chlorine / chloramine?
I have a 15 gallon reservoir that has roughly ten to twelve gallons in it which leaves 2.5 to 3 gallons in each of my two buckets. I am experiencing about a gallon a day loss of water and my ppm fluctuates about 10 - 30 a day either way so not too much. I just checked the PH after adjusting this morning and its holding steady at 6.2 we will see as the furnace is on more at night. Mine is about 10 foot away from the furnace.

Now here is what is disturbing me. Gas furnaces do not emit co2 they emit carbon monoxide or co. So if it is a furnace issue then its the co entering water system. We have a carbon monoxide alarm upstairs but not downstairs. Is your furnace operating efficiently? Filters changed?

I've noticed yours is dropping a lot more than mine. Perhaps a bigger reservoir will help in slowing that down? I am using city water. We have some pretty bleachy smelling water and it really hasnt affected anything. Tap PPM runs about 100 to 110
 

DukeO

Well-Known Member
(Water level in my 5-gallon reservoir dropped by about a pint in 16hrs.)

(This DWC is supporting a single plant that has been growing strong for 12 weeks now.)

One of my plants that has veged for about 4 weeks and is in week 3 of flower will drink well over a gallon a day.

I have been running DWC buckets for many years.

I pretty much never do a full rez change anymore and I never clean/wash any buckets through the whole grow.

When I first started out I was using GH and I was running into a lot of the issues your seeing.

I grew some great plants with it. But I found it to not be very stable and it is just loaded with dyes.

I was also having root issues that would make my PH drop like a rock at times.

I moved over to Botanicare Kind and it is very stable and very very clean.

I use that with z7 water treatment and tap water and pretty much all my issues have gone away.

If your already paying for ro the z7 will pay for itself.

It will also keep your roots free from rot and keep your rez clean and ph more stable at the same time.
 

JD77

New Member
Duke0 there you go promoting that z7 again lol. I am gonna get some here soon, money has been super tight. Hows the price of the Botanicare compared to GH? Is it nutrients or PH adjustment stuff? I have about a half a quart of micro, grow, and bloom left.
 

DukeO

Well-Known Member
Duke0 there you go promoting that z7 again lol. I am gonna get some here soon, money has been super tight. Hows the price of the Botanicare compared to GH? Is it nutrients or PH adjustment stuff? I have about a half a quart of micro, grow, and bloom left.
It is not much more then GH and it has more ph buffers then GH. You should give it a try when you run out of GH.

A three pack of quarts is about $50 and 3 pack of gallons about $110

They are a three pack. But you only use two at one time. So base and veg or base and bloom.

It seems to last for a long time to me. But I have not compared just how much a gallon of mix from each cost.

Just because something my cost more per gallon to buy it still may be cheaper over the long haul when mixed.

My guess is you will never go back once you try it. LOL

After I tried it I gave all the rest of my GH away.
 
Thread starter #17
Thank Mad for that chart.

OK, so I managed to get my air temperature to stabilize at 70 degrees. I have the reservoir stable at 65 degrees. That's the best I'm gonna be able to do as far as temps go.

I completely understand how temps are important. However, I don't see how temps address my original problem of PH crashing each day.

Based on my own scouring of the internet, PH drops in Veg are usually caused by one of the following:

-- A bacterial / algae infection at the roots
I feel I've already ruled that out. My roots look good and clean, the water smells clean, and I change the reservoir weekly. I also use HydroGuard in the res between water changes.​
-- Nutrient strength is too high
I was feeding as high as 900 PPM but have cut it back to as low as 350 PPM. Still, my PH drops by about a full point each day. I am currently feeding at ~550 PPM.​
-- Somehow, I'm in a CO2-rich atmosphere and I'm pumping CO2 into the reservoir
I have no way to check the CO2 concentrations in my basement so I'm clueless there.

Tomorrow, I'll do another reservoir change and this time I'm going to use tap water and hope for the best. I've tested it to 180 PPM and a PH of 8.5. If the PH in my reservoir continues to drop each day, then I simply have no choice but to keep using PH-Up every day to get my PH back in range.
 

JD77

New Member


Lemme know if you have any questions about the chart
I've got this printed out in my book next to my logs and feeding chart. Very useful info. I will post my ph in the morning.

Duke0 I will definitely give it a try next round of nutes I buy. I dont think I will run out this grow but I am definitely getting the z7 soon. Also could you point me to a feed schedule for those botanicare nutes? I am using the hydroguard and love it.
 

TheMadDabber

Member of the Month Dec 2017
In a relatively equaliberated state your Ph should only rise slowly. Check you TDS for rising falling or static levels. As well as you water level (it will never rise but static or falling, you want falling or the plants not drinking).

That info will provide all we nees to get you on track friend!
 

TheMadDabber

Member of the Month Dec 2017
Im 99% you need to go back down in EC aka TDS. Do not please do not put that high pH tap water in the res. 6.5 max 7 if you feel extra froggy. Add 150 ppm cal mag and not a drop of anything else. Also dumb question but your phing After adding all your nutes and supps correct?