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

[Sammy]

I've had similar problems as you're experiencing, what fixed it for me or at least what I think fixed it for me I change nutrients started with a cyco line of nutrients. My reservoir is 4 and 1/2 gallons, I run a little Chiller water temp stays 63 62 degrees , I'm running at full strength my PPM comes in between 11 and 1300. If I start out with a pH of 5.6 it rises pretty quick of the next 12 to 18 hours then it settles in about 6.2 . I have only had to adjust it one time from being out of the typical range and that was showing 6.8 plant never looked unhealthy always green drinking much more than one gallon per day. I top off with ph plain pH water, of course with hydroguard good luck ☮️

[JohnC]

Have you tried calibrating your ph meter dude?

Of course, I did. I have Blue Labs PH and PPM pen testers, calibrated weekly using General Hydroponics calibration fluids.

[Vapo69]

Ok, just wondered.......isn't calibrating weekly too much?

[JohnC]

I have no idea if calibrating each week is too much or not. I wouldn't think so.

[JohnC]

OK, so I went to my supermarket to buy some fresh water. What a surprise this has turned out to be. The "RO" water I have been buying tested to a PPM of 220 and a PH or 6.9. These are not the values I would expect from RO water, which should have a PPM of 0.

So now what do I do? If the supermarket water is not what it is claimed to be, do I just use tap water (PPM = 180, PH = 8.5) and stop wasting money on store-bought water?

This doesn't explain why my PH is dropping so much each night, but I do have to wonder about this water I'm using.

[Jason]

I use tap water. Run, add nutes, shaken not stirred, add to the WaterFarm. No rest from running it into the gallon jug, adding nutes and pouring over the clay balls.
Unless you have some wonky tap water, give it a try.
I haven't consumed the stuff personally since the mid '70's, but it seems to work really well for my girls.

That is a bit weird that your RO grocery store water has PPM of 220. that is WAY off. I'd contact the company after calibrating the measuring tool to confirm.
You might get some good free RO water out of it.
Good luck.

[GanjaGed]

Yea that seems way high, mine tests at 20 ppm or lower, though never 0

[Obi-Wan]

If I were you I would switch to tap water and use the 1/3 strength nutrients based on your feed chart. Your municipal water supply may contain trace minerals that will better buffer the pH and slow the drop.

[JohnC]

Good morning, folks. Another day, another PH drop.

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.

However, I think I have figured out the issue. There simply is no other explanation that I can think of.

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?

[Jason]

Use tap water. Besides, it sounds like the RO water you're getting is a bit sketchy.
Could a bit of ventilation reduce the CO2?

[tvbfe]

I would try tap water.

[Obi-Wan]

Is it possible to change the source of air for your pump? Pulling fresh outdoor air for the pump should fix the issue.

[JohnC]

Not without putting my air pump outside of the house or on another floor of the house.

[JohnC]

OK, 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 is my res 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.

[Jason]

O2 from the air stones moves pH up. And the 02 is antibacterial, which is good for root health.
Why remove them?

[GanjaGed]

Too much O2 causes an acid rain effect. This is often seen in hydro symptoms as Water/PPM stay stagnant and PH drops.

I'll post a chart of symptoms below (don't know how to do it in comments, lol)

[GanjaGed]

But if he's finding the buffers in tap water to work then there's that too. There are many factors that can cause things. I responded to the too much O2

[JohnC]

Interesting update this morning.

Yesterday, I experienced another unexplained drop in my reservoir PH. Yesterday morning, I added my usual 2ml of PH-Up to the reservoir to bring the PH back up to 6.1. Believe it or not, by 4:00 p.m., the PH had dropped to 4.3! I was livid to say the least.

So, at 4:00 p.m., I drained and refilled the reservoir again, this time using tap water. I mixed up my nutrient solution to 590 ppm and PH of 6.6. I left out Cal/Mag, assuming that the tap water would provide these elements. I did, however, add in 10ml of Hydroguard after I mixed everything up. Lights then went off at 7:00 p.m.

This morning at 8:00 a.m., I went to the basement to check on my lady and take some readings. The water level in the reservoir went down by about a quart overnight. The PH dropped slightly to 6.4 and my PPMs went down to 580 ppm. Air temperature is stable at 71 degrees and water temperature is steady at 67.4 degrees.

Based on today’s readings, this is my understanding. She is drinking and eating, albeit a small amount, which I guess is to be expected after the roller-coaster ride she’s been having. I went ahead and added 1.5ml of PH-Down to the reservoir to bring the PH down a little bit more. I also added some plain RO water to bring my water level back up.

So how do I proceed from here?

[Jason]

So with tap water pH went from 6.6 to 6.4? That seems to be an improvement over the RO water.
I'd just stick with tap water.
Tap water does not provide Cal/Mag. At least mine doesn't so I add that. No Hydroguard here.

[GanjaGed]

Jason

This is the symptom chart. It's just one method of diagnosis,

[Jason]

Cool chart. I think it says too much CO2, not 02 in the 3rd box from the top. I'm not familiar with the acid rain effect.
Checking air source for high CO2 would be something to do.
Also Note 1 is mentioned, but not on the chart.

The chart also says if pH is static that is "perfect". I don't know about that. GH says pH should range to insure all nutes are absorbed. They print a chart to show what is absorbed at what pH. I like to see mine range up due to 02. If it stayed static, I'd be concerned, just because
my WaterFarms don't do that.

Looks like most of the solutions involve res change. I don't measure PPM at all. pH three times a day, and add balanced water to over flow the drilled hole for the air stone line. I add water twice a day.
Just mixed up Week III nutes and everybody is very happy.

[GanjaGed]

I use it as a diagnostic tool, my res runs about 30 days on avg between changes.

It's by no means comprehensive. Slowly drifting PH isn't a bad thing.

Res changes can often solve problems esp. for newer hydro growers so it makes sense to include that in a list of possible solutions. In fact my res starting to do something out of the ordinary almost always triggers a solution change for me.

[Jason]

I change my 2 gallon res every 6 days. At times pH can range up a full point in 3-5 hours. Other times, its fine or fine enough for days. I just measure and adjust as needed.
I have no experience with a system that is changed every 30 days. That would seem to extend the growing period quite a bit. I use the GH 12 week schedule and then extend for ripen and flush.
When I got my second WaterFarm, I forgot to wash the clay balls. That created a week of constant adjustments. Other than that, I haven't had any problems.
And the resulting flower is incredible.

[JohnC]

Well, my excitement was short-lived. Using tap water in my reservoir, my PH dropped from 5.8 yesterday afternoon (It was 6.1 in the morning) to 5.2 this morning. She drank a bit less than a quart overnight.

So I topped off the reservoir with some nutrient water and added 2ml of PH-Up to the reservoir. I can only imagine the adding PH-Up to a reservoir that already has a bunch of PH-Down swimming in there cannot be good for the plant.

[Jason]

Ranging a point a day is something I see during Flower. But mine ranges up due to added 02 from the air stone.
Ranging like that is supposed to be healthy as different nutes are absorbed at different pH levels. GH puts out a charts to show this. My guess is the chart NOT is based
based on our girls, just plants in general.
I've never read that the pH adjustments interfere with the plant. So you probably don't need to worry about pH UP and pH DOWN making her bipolar or stressed.
6.1 to 5.2 is a very good range for nutrient absorption.

[JohnC]

Yes, I'm well aware that my PH should be ranging up during veg but mine ranged DOWN almost the entire time, and by a significant amount each day. There has to be a reason for it and so far I'm getting nowhere towards finding that out.

[Jason]

Maybe check the CO2 level in your room. If the air pump is pumping that into your res, that will contribute to what you're seeing.
My grow room is one thin wall away from our gas furnace. I don't know of any negative effects due to that proximity.
The ranging you're getting is good for nutrient absorption. As long as its not inconvenient for you to adjust, maybe just go with it.
My WaterFarms both blasted UP a full point yesterday. I adjusted slightly early evening, so they could have some high pH nutrients. This morning I got it back down to low 5. I'm in an 18/6 light/dark schedule at the moment.