DWC Hydroponics water PH drops over time

[FlyingDutchPaddy]

Update for today, i checked pH at midday - measured 7.3

Yesterday evening after complete water change, pH was 6.5

What I'd previously do was add pH down to the main res to bring it back down to 6.5 from 7.3 now, but i'm not sure if doing that is a good idea.
(used to add around 8 - 11 ml in total of pH down to the system)

Reasoning: adding pH down now to bring the system to 6.5 (when it settles) will result in pH dropping down to the 5.5 region in a couple of days...

I'm wondering...
I havnt been adding extra water to the res between water changes - difficult to see water level in the level checker as it is the growtent....
As the plants drink up the water, they wouldn't be taking up any of the extra H ions from the pH down.... ?

if thats so, less water, same amount of pH down... pH down concentration in system would go up, lowering pH more...

so solution would be: adding water when pH goes below 5.8 to dilute pH down in the system so overall pH goes up again?

[FlyingDutchPaddy]

Campesino, nothing besides the GH Flora Trio, and Essentials pH down.

I do think i need to get some Cal-Mag supplement for the small brown spots that are starting to appear on most leaves now...

[Campesino]

You need to get 29% H2O2 and add 2.5ml/gal to the Res! This will kill bacteria and add oxygen to the water. I also recommend using SM-90 in the Res, also 2.5ml/gallon. This will also help fight bacteria and offers a number of other benefits. I suspect you might have trouble getting SM-90 if you can't get hydroguard, but you should be able to find 29% H2O2

[IslandColas]

Loving the new ph! You doing great brotha just keep it up. I can tell you spend a lot of time thinking about your crop. That will pay off in the end. Lots of meticulous growers produce some fire crip.

[FlyingDutchPaddy]

Good morning everyone

lighting has just begun so I took a measurement @ 20180610 - 10:20 ; pH = 5.9
just about perfect... now it needs to stay there...

[DankwingDuck]

that ph is perfect .

[IslandColas]

Love your ph!!! Much props

[FlyingDutchPaddy]

Update for this evening, @ 20180610 19:00 - pH = 5.8

earlier this afternoon around 16:00 i measured 5.7 so I filled up with 1 L of nute water (1ml micro / 0.3 ml gro / 1.7ml bloom) at pH 7.0
just topped up by another 1 L of plain water @ pH 7.3.

will check again in 2 hrs just before lights out.

[IslandColas]

You’re on it brotha! Keep it rocking and you’ll be pleased at harvest! Is it just me or does the res seem to be stabilizing a bit?

[FlyingDutchPaddy]

Hi IslandColas ,
I’m keeping a close eye on it during the weekend...
Now that Monday is approaching, can only measure & take corrective action in the evening...

But it seems to be on target now after adding a L plain water & 1 L nuted...

Thanks for the comments

[IslandColas]

Please keep me posted as much as you can. I only check my reservoirs once daily during the week as well. I’m near positive it will stabilize if you just continue your small adjustments and continue to change your reservoir every 7-10 days

[FlyingDutchPaddy]

Monday evening update. 20180611 @ 18:35 - pH = 5.3

Added 1L of water containing:
20ml CalMag
20ml pH up
20ml H202 (12%)

pH of that L was 11.1

will measure pH again before lights out to see what it stabilises on.

[FlyingDutchPaddy]

@ 20:15 - pH = 6.4 in main res & one of the buckets.

[FlyingDutchPaddy]

Update 20180612 @ 19:10 - pH = 6.3

added 1L plain water, and 2ml of pH down to lower it slightly.

[Campesino]

I am not familiar enough with re-circulating system set-ups. I'd have more questions than answers at this point.

You'd get some other good opinions if you post your issue here ( IslandColas new thread) : https://forum.growweedeasy.com/forum...-growers-group

[Obi-Wan]

I just did a quick search on your particular rdwc system. The diagram that the company provides shows air stones in the individual grow buckets but I don’t see one shown for the reservoir, does it have an air stone that I don’t see in the diagram? I setup my own system with a similar design but I use an air stone in the reservoir to churn the nutrient solution as it drains back into the reservoir.

[FlyingDutchPaddy]

Obi-Wan , from the manufacturer it comes standard with 4 air stones for the buckets, indeed. There is no 5th airstone for the main res.
i suppose i could get another air pump and put the spare airstone in the res...

thanks for the idea

[IslandColas]

current reading @ 20:45 - pH = 6.1

IslandColas, @Campesino,
I have an idea about what may have been happening.

the pump that is recirculating the water from the main res was sitting on the bottom, exact same level as where the drain hoses from the buckets were coming back to the res.

i have a feeling that the water being recirculated was not properly remixing with the water already in the main res, causing this rapid drop in pH over a few days.

what i've done is raise the pump to just under water level in main res leaving enough for consumption of the plants/evaporation so its doesnt go dry.

would you have other idea's about this?

thanks

If can, I would make the drain hoses introduce the water from the top of the reservoir and keep the pump at the bottom. This ensures you have a full mix of your nutrient solution before it gets sucked back into your buckets. You could also use waterfall effects to achieve extra aeration/agitation.

[Sockfilter]

Agreed on the return nutes.

I had a 4'x4' flood and drain table with 40gal rez feeding the table. The return just drained back into the rez by free falling and splashing into the rez (yes lid on it). That creates more O2 in the rez.

Also on the pump within the rez, I added another small pump just to keep the rez constantly mixed up, combined with the vast surface area of the res, O2 was naturally absorbed and I never had to run an air stone and pump.

However keep in mind that this was a big rez that could handle and dissipate the additional heat the extra pump introduced into the rez..

More than 1 way to skin a cat and just throwing out other ideas that may or may not be useful in your endeavor

Sounds like you are dialing it in FDP..

[IslandColas]

I am not familiar enough with re-circulating system set-ups. I'd have more questions than answers at this point.

You'd get some other good opinions if you post your issue here ( IslandColas new thread) : https://forum.growweedeasy.com/forum...-growers-group

YES! Spread that feed link everywhere! You’re awesome!!!

[gbauto]

I have used GH Flora trio for 3 years in my RDWC system. Total capacity is 25gal. My well water is 6.9@ 45ppmTDS I think that GH uses pH buffers to target pH around 5.5 when mixed with RO water. I tend to start at 5.5 and then use pH up to drift towards 6.5 over the 10 days between fluid change.

[FlyingDutchPaddy]

pH for this evening ; 20180613 at 18:30 - pH = 6.0 in main res & one bucket.

only 0.1 drop in pH... seems to be stabilising... but needs a watchful eye.

will comment with again just before lights out.

[FlyingDutchPaddy]

at 20:45 - still pH = 6.0
no water added today...

[FlyingDutchPaddy]

This evenings measurement, pH = 5.9 at 20:50

[FlyingDutchPaddy]

Friday afternoon update, 20180615 at 17:20 - pH = 5.7
topped up with 1.5l of nuted water that measured 6.9.

will let that circulate through the system so it settles...
comment later on what it stabilises to...

[FlyingDutchPaddy]

Update: after settling pH was 5.8...
Added 4ml of pH up and before lights out was at 6.4 @ 21:00

[FlyingDutchPaddy]

Morning update 20180616 at 10:45 - pH = 6.4

[FlyingDutchPaddy]

This afternoon update, pH was 6.4
added 1.5 L of water with 20ml calmag extra.
measured 6.2 afterwards.
comment later this evening before lights out.

[FlyingDutchPaddy]

pH still at 6.2 at 18:20

[FlyingDutchPaddy]

New week, new monday... new measurment...

20180618 at 19:00 - pH = 6.0

0.2 drop over about 25 hrs...
2 of 3 plants starting to look ready...
3rd 'mystery' plant is growing big.... lots of budsites...

spots on leaves seem to have stopped spreading...

will need to change water tomorrow, been 10 days now since last complete change.

[FlyingDutchPaddy]

Tuesday 20180618, change all the water day... receive TDS meter day

TDS meter is NaCl (salt water) factory calibrated to 342 ppm

2 measurements before the water change: pH & ppm.
Before changing water pH measured at 5.7
Standard tap water ppm = 244

So, change of water details:
Quantity = 45 L
3x 15L , per 15 L measurements were:
micro - 30 ml - ppm 596 - pH 7.3
Bloom - 60 ml - ppm 737 - pH 6.3
CalMag - 30 ml - ppm 669 - pH 7.4

After adding all 45 L to res & buckets,
average ppm = 645
average pH = 7.5

waterpump & air stones on for 10 mins;
ppm = 653
pH = 7.5

Added 8.5 ml pH down, let it circulate for 30 mins.
ppm = 650
pH = 6.5

Resting pH after plants were put back in at 20:45 - 6.7

Will see what happens overnight...