DWC Bhut and Reaper... pH dropping very fast

MNXR250R · Sep 17, 2017

Greetings to All.

I have two separate Deep Water Culture systems running inside of a single 4x4 tent. One of the systems has been a constant chore to adjust the pH (up) from the start (Bhut), and the other system was pretty stable until the last yew days (Reaper). Now both systems need a charge of "pH UP" every day.

Both plants were started in Rock Wool and I have not removed them from the initial starting cube. I transferred the two plants from a grow dome into the DWC about three weeks ago.

I'm using General Hydro "Flora Series" in a 5 gallon bucket for each plant. First plant is a Bhut Jolokia and the second plant is a Reaper.

My nutes for both plants are the same. I use about 1/3 TAP WATER (for pH buffering) and the remainder is RO water. I mix the nutes and then adjust the pH to 6.0 with pH DOWN.

The Bhut required pH adjustments every day (fairly large adjustemts like from 5.4 up to 6.0, while the Reaper only needed minor adjustment once or twice in the three weeks.

Today the Bhut is dropping very fast (from 6.0 in the morning to 5.2 in the evening). The Reaper is starting to drop more rapidly but not like the Bhut. Reaper will drop from 6.0 in the morning to 5.7 or 5.6 in the evening.

My concern is that I am adding what seems to be a lot of pH UP to keep the system where it should be.

Is this normal ? I have nothing but rock wool and clay balls in the system.... I can't see any good reason for the pH to drop except that the plants themselves are doing it.

Any help would be appreciated.

Thanks,

Jeff

Spokanepepperman · Sep 17, 2017

What are your water temps water temps can swing ph wildly from my experiences.

MNXR250R · Sep 17, 2017

Spokanepepperman said:
What are your water temps water temps can swing ph wildly from my experiences.

Hey Spokane, the temps do vary quite a bit in the solution. Prolly from upper 60's to low 70's in the early morning to almost exactly 84 during the lights on period.

I thought that I knew what pH was.... hydrogen ions and hydronium ions and all. Temperature never entered my mind. I never thought that the temperature would have an effect. But apparently it DOES.

In my case however, over the low temp to high temp cycle, day in and day out, the pH is clearly drifting to the acidic.... and quickly :surprised:

. My concern then is still about adding so much "pH UP" to keep the pH in range.

I will be watching the temps and the variation in pH. Perhaps there is a "best time" to add adjustments.

Happy Growing !

Jeff

D3monic · Sep 17, 2017

I'd check ph at the same time each day. In my aquarium the ph drifts drastically at lights out, During the day, I inject CO2, that drives ph down. At night the PH goes up from the plants

MNXR250R · Sep 17, 2017

D3monic said:
I'd check ph at the same time each day. In my aquarium the ph drifts drastically at lights out, During the day, I inject CO2, that drives ph down. At night the PH goes up from the plants

D3monic.... I can't disagree with measuring at the same time every day. Make sense.

But I am seeing that the pH is dropping consistently. I add pH DOWN every day, and then again every day after that.

I'm hoping that sooner or later the pH will stabilize ... but hoping isn't knowing.

On a side note, I used to keep live plant aquariums (1996 to 2010ish. I had two 55 gallon tanks with T-8 grow lights. It was fantastic ! I had one plant that I loved more than any because of its color. It was a Hygrophila. Don't know the exact species but it would produce the most fantastic Fuchsia and Purple new growth. I had more than 50 fish per tank. I do miss changing the water over week or so ( or NO.... I don't :party:

)... I still love aquariums !

Thanks for the reply and Happy Growing !

Jeff

Biggy · Sep 17, 2017

How often are you changing water? Adding ph adjustments all the time will throw your nutrient solutions out of wack. I have the opsite problem. Mine always floats way up so I'm always adding phosphoric and or sulfuric acids to bring it down. After a few days the tds reads fine but in all actually I'm reading lots of sulfer and phosphorus and not much fertilizer. How long do you wait to test after adding? Mine will drop way down but after a hour or so it will stabilize to the actual ph. I use part well water that's extremely high in calcium bicarbonate hence the opsite problem that you have. I would recommend upping your tap water to better buffer the wild swing that too much ro will give you. I shoot for ph 5.5-6.5 with tds of 550-650. Peppers are pretty forgiving as long as you don't run the tds way high.

MNXR250R · Sep 18, 2017

Biggy said:
How often are you changing water? Adding ph adjustments all the time will throw your nutrient solutions out of wack. I have the opsite problem. Mine always floats way up so I'm always adding phosphoric and or sulfuric acids to bring it down. After a few days the tds reads fine but in all actually I'm reading lots of sulfer and phosphorus and not much fertilizer. How long do you wait to test after adding? Mine will drop way down but after a hour or so it will stabilize to the actual ph. I use part well water that's extremely high in calcium bicarbonate hence the opsite problem that you have. I would recommend upping your tap water to better buffer the wild swing that too much ro will give you. I shoot for ph 5.5-6.5 with tds of 550-650. Peppers are pretty forgiving as long as you don't run the tds way high.

Hey Biggy. These buckets of nutes are under two weeks old. I'll be changing every two weeks.

I don't wait very long after adding the pH UP before measuring... maybe two minutes. That's plenty of time for the ions to move around.

Our tap water is runs 3-400 ppm bicarbonate (so 1/3 tap 2/3 RO gives 100-133 ppm CO3). I measure 1100 ppm with a TDS meter so that makes the nutes somewhere around 1000 ppm. I've been using the General Hydroponics guidelines for "early growth". Maybe try a little lower on the next mix to see if that helps at all.

Thanks for the reply,

Jeff

OoNickoC · Sep 19, 2017

MNXR250R said:
Hey Biggy. These buckets of nutes are under two weeks old. I'll be changing every two weeks.

I don't wait very long after adding the pH UP before measuring... maybe two minutes. That's plenty of time for the ions to move around.

Our tap water is runs 3-400 ppm bicarbonate (so 1/3 tap 2/3 RO gives 100-133 ppm CO3). I measure 1100 ppm with a TDS meter so that makes the nutes somewhere around 1000 ppm. I've been using the General Hydroponics guidelines for "early growth". Maybe try a little lower on the next mix to see if that helps at all.

Thanks for the reply,

Jeff

I cant believe i didnt ask, did you try to ph the runnoff of the wonky plant? by this i meant run ro water though and collect the effluent to see if the hydroton/clay was somehow buffered with a salt or something at some point.

MNXR250R · Sep 19, 2017

Hey OoNickoC, Not sure what your asking. Flushing a system with R/O and measuring the pH of the runoff is a technique used with soil or soil-less systems. In my case, I am running DWC and I have no soil.

HOWEVER, I have wondered about the influence of the clay pebble substrate (Hydroton) on the system. From everything that I have read, the Hydroton is completely inert. That is not so say the the Hydroton will not hold ions, but it is not supposed to affect the pH of the system.

I don't know for sure.

Happy Growing,

Jeff

D3monic · Sep 20, 2017

What Nutrient solution are you using? I used to use Sensi Bloom/grow with PH perfect. It's a pretty good product and maintained PH at a level I didn't need to adjust.

OoNickoC · Sep 20, 2017

MNXR250R said:
Hey OoNickoC, Not sure what your asking. Flushing a system with R/O and measuring the pH of the runoff is a technique used with soil or soil-less systems. In my case, I am running DWC and I have no soil.

HOWEVER, I have wondered about the influence of the clay pebble substrate (Hydroton) on the system. From everything that I have read, the Hydroton is completely inert. That is not so say the the Hydroton will not hold ions, but it is not supposed to affect the pH of the system.

I don't know for sure.

Happy Growing,

Jeff

I had a small bag of hydroton that had a ph of like 7 and one with a ph runoff of like 6.2, I had to soak the 7 in a 6.0 for a day or so. I assumed that might happen every now and then if it gets exposed to water in the bag and sits wet for a while.

mrgrowguy · Sep 20, 2017

What is the health of the root mass? do you see any browning or greying? anything look like it might be dying? If you have anything but healthy white roots, you may be getting a ph swing from decaying matter. It happened to me once when I pinched an air line and the plants went two 24 hr periods without air. The plant's roots just barely started to die, I thought I caught it in time, but I noticed I was having to adjust the ph more and more, similar to what you're having to do.

If you have super healthy roots, pearly white, and can write off decay as a troubleshoot, then how is the health of your plant's top growth? If it is super healthy, than it may be possible that your plant is taking in all the nutrients that you balanced out with the ph down, once it takes the high ph nutrients, it leaves the low ph down solution, causing the res to become increasingly more acidic. Though, if I were to take a wild guess, I would still lean towards possible root decay as the actual reason for the ph swing.

Just a few thoughts... hopefully they either help or you can at least write them off as simple troubleshooting and move on to other possibilities.

:drooling:

.

MNXR250R · Sep 20, 2017

OoNickoC said:
I had a small bag of hydroton that had a ph of like 7 and one with a ph runoff of like 6.2, I had to soak the 7 in a 6.0 for a day or so. I assumed that might happen every now and then if it gets exposed to water in the bag and sits wet for a while.

OoNickoC. Everything I read about the Hydroton is that is was pH neutral. But I've read a few things that turned out to be less than accurate. Next run I'll take Hydroton and soak it in ph 6.0 . Maybe this will help.

Thanks for the input !

mrgrowguy said:
What is the health of the root mass? do you see any browning or greying? anything look like it might be dying? If you have anything but healthy white roots, you may be getting a ph swing from decaying matter. It happened to me once when I pinched an air line and the plants went two 24 hr periods without air. The plant's roots just barely started to die, I thought I caught it in time, but I noticed I was having to adjust the ph more and more, similar to what you're having to do.

If you have super healthy roots, pearly white, and can write off decay as a troubleshoot, then how is the health of your plant's top growth? If it is super healthy, than it may be possible that your plant is taking in all the nutrients that you balanced out with the ph down, once it takes the high ph nutrients, it leaves the low ph down solution, causing the res to become increasingly more acidic. Though, if I were to take a wild guess, I would still lean towards possible root decay as the actual reason for the ph swing.

Just a few thoughts... hopefully they either help or you can at least write them off as simple troubleshooting and move on to other possibilities.

.

mrgrow, the roots look ok to me. Pearly white is how I would characterize them. The upper leaves look very good. Too good actually ! I have leaves on the Reaper that are as big as my hand :dance:

Now... the Reaper hasn't been that plant that I have had to adjust the pH all that much. Every day yes... but less than 1mL UP (in 2.5 Gal). The Reaper is growing like.... CRAZY !

The plant I have to adjust a a lot, and the one that is causing the most concern is my Ghost. The Ghost isn't nearly as "robust" in growth as the Reaper. Both of these plants started in the DWC buckets at the same time, and both were about the same size (close enough to say "same size"). The Reaper is 2.5 to 3 times the mass of the Ghost (visual estimate). Also, the Ghost roots are not what I would expect. The root density is nothing compared to the Reaper.

Today was a little different. Both plants were adjusted last night to about 6.2. I left them for a full 24 hours (had to work eh). This evening the Ghost was at 5.8, and the Reaper was at 6.1. So I didn't have to add so much "UP".

Anyway, thanks for the information !! I'll be watching the roots from now on

Happy Growing,

Jeff