Possible phosphorous deficiency advice needed

[Sam1992]

Hi all, first post on here so please be patient lol.
First grow started about two weeks ago.
Plants are we're looking healthy up until a few days ago one developed a few brown marks on the lower leaves also slight yellowing of the leaves, self diagnosed as possible phosphorus deficiency looks the most likely.
Set up is great no temp fluctuations, ph went low a few days ago dropped down to about 4.5 from 6.0 but i quickly rectified, could this cause phosphorus deficiency?
It's dwc 20L with air stone, under an air cooled 600w hps. Using canna aqua Vega for my nutes will be going over to aqua florres in a few weeks. Started off on low dose of nutes about 1/4 strength to prevent nute burn, after my first water change I upped the dose to 1/2 recommend, also added a few ml of cal mag. Roots are growing fantastic also.

Any common causes of phosphorus deficiency in a dwc setup?

 

[OG1969]

That big a ph swing could be it. I would keep ph 6 to 6.2 weed doesn't like much below 5.7 brother.
Peace OG

 

[Chris Scorpio]

Looks pretty healthy, and welcome aboard

I'd suggest adding Calmag and an add an enzyme cleaner like hydroguard or z7,z9 outside the USA

And keep an eye on that pH , RO water or tap

I get a few low leaf issues in DWC assss well, don't worry to much yet

How far below the net pot is yer watter at

 

[Emilya Green]

Hi all, first post on here so please be patient lol.
First grow started about two weeks ago.
Plants are we're looking healthy up until a few days ago one developed a few brown marks on the lower leaves also slight yellowing of the leaves, self diagnosed as possible phosphorus deficiency looks the most likely.
Set up is great no temp fluctuations, ph went low a few days ago dropped down to about 4.5 from 6.0 but i quickly rectified, could this cause phosphorus deficiency?
It's dwc 20L with air stone, under an air cooled 600w hps. Using canna aqua Vega for my nutes will be going over to aqua florres in a few weeks. Started off on low dose of nutes about 1/4 strength to prevent nute burn, after my first water change I upped the dose to 1/2 recommend, also added a few ml of cal mag. Roots are growing fantastic also.

Any common causes of phosphorus deficiency in a dwc setup?

First, ph should be n the hydro range, 5.5 to 5.8... the above recommendation of 6.2 would only be applicable in soil. Second, your are in veg... phosphorus is not even needed other than in trace amounts right now. Your deficiency looks like magnesium to me... very common and easily fixed, get some calmag in there. I would try full strength nutes too... and then see if you get a nute burn simply by following the directions... if and only if, then back down. You are growing DWC so you can get extraordinary growth, but you aren't going to get that being timid.

 

[Sam1992]

Hi guys thanks for the reply.
I added cal mag but only about 3ml to the 16l of water. Regular tap water left out for 24hrs to get out the chlorine then add nutes and check for correct ph. I've not been keeping a close eye on the ph as I just assumed it was set and wouldn't fluctuate too much. Water is about an inch or so below the net pot

 

[Emilya Green]

Hi guys thanks for the reply.
I added cal mag but only about 3ml to the 16l of water. Regular tap water left out for 24hrs to get out the chlorine then add nutes and check for correct ph. I've not been keeping a close eye on the ph as I just assumed it was set and wouldn't fluctuate too much. Water is about an inch or so below the net pot

You might want to check with your local water company and see if they use chlorine or chloramine like most modern cities do these days, because chloramine does not evaporate by sitting it out. Follow the recommended dosages of calmag for your volume of water and I bet your problem clears up if you get the pH correctly adjusted.

 

[Chris Scorpio]

Do full strength on that calmag my friend

But I disagree on the full strength nutes unless yer a seasoned grower. I've always run half strength in my DWC with great results, so just be careful

 

[Sam1992]

Awesome advise guys, done recommended cal mag strength and I'll keep a close eye on the ph. Keep you posted over the next couple days.

 

[Sam1992]

Day 20 veg.
Evening guys and girls, just a quick update after adding cal mag, recommended dosage 1ml per L plant appears to be in the same state if not a lil worse 24hrs later... I'm assuming it'll take a few days for it to have any noticeable effect? Could it be I'm not using enough of my aqua Vega for it to be getting sufficient nutrients, I just don't want to make any quick harsh decisions and over do it on anything.

 

[Growingasmile]

Day 20 veg.
Evening guys and girls, just a quick update after adding cal mag, recommended dosage 1ml per L plant appears to be in the same state if not a lil worse 24hrs later... I'm assuming it'll take a few days for it to have any noticeable effect? Could it be I'm not using enough of my aqua Vega for it to be getting sufficient nutrients, I just don't want to make any quick harsh decisions and over do it on anything.

This chart is useful I love it.

 

[Growingasmile]

Awesome advise guys, done recommended cal mag strength and I'll keep a close eye on the ph. Keep you posted over the next couple days.

this could be a PH issue dwc p.h. is better around 7 for me but it really depends on strain and other factors, or oxygen deprived roots what type of air pump are you using?

 

[Sam1992]

This chart is useful I love it.

This is what partly led me to believe I was dealing with a phosphorus deficiency, still unsure of what the problem is though :/ had some good advice already just trying to keep a close eye on it all.

 

[Mikesem420]

@Growingasmile I think your right I have an issue just like that thought it was calmag but i found out I had the pump plugged into the light timer switch so the pump was off for 6 hours a night its improved since I've switched it but I think it was lack of air and calmag deficiency I read that calmag wont absorb at low temps and my veg closet was down too 66° the other night I brought it back up to 72° with a space heater and flushed so far so good..

 

[Sam1992]

this could be a PH issue dwc p.h. is better around 7 for me but it really depends on strain and other factors, or oxygen deprived roots what type of air pump are you using?

Keeping an eye on the ph trying to aim for 6.0-6.2
Standard aquarium air pump with two outlets being used. Not sure if you can see but the 4inch round vent in the bottom corner is my fresh air intake with two inline fans pumping air in. Also the pump is almost right next to that so plenty of fresh oxygen and plenty of bubbles....

 

[Growingasmile]

I think your right I have an issue just like that thought it was calmag but i found out I had the pump plugged into the light timer switch so the pump was off for 6 hours a night its improved since I've switched it but I think it was lack of air and calmag deficiency I read that calmag wont absorb at low temps and my veg closet was down too 66° the other night I brought it back up to 72° with a space heater and flushed so far so good..

You're kinda right but DWC tanks should stay at or just below 70f because much above it and the water will have less dissolved oxygen in it.

 

[Growingasmile]

Keeping an eye on the ph trying to aim for 6.0-6.2
Standard aquarium air pump with two outlets being used. Not sure if you can see but the 4inch round vent in the bottom corner is my fresh air intake with two inline fans pumping air in. Also the pump is almost right next to that so plenty of fresh oxygen and plenty of bubbles....

That's definitely enough bubbles, I would make sure reservoir temps are about 70 degrees and I would keep a very close eye on ph

 

[Sam1992]

@Growingasmile I think your right I have an issue just like that thought it was calmag but i found out I had the pump plugged into the light timer switch so the pump was off for 6 hours a night its improved since I've switched it but I think it was lack of air and calmag deficiency I read that calmag wont absorb at low temps and my veg closet was down too 66° the other night I brought it back up to 72° with a space heater and flushed so far so good..

Thanks for the reply.
Air pump has been on constantly. Except an hour here and there for maintenance.
Temps are also very steady at 25°c in the day lights on and 20°c at night lights off.
All foods etc are kept close by but not in the room.

 

[Emilya Green]

Sorry, been out of town all day... magnesium deficiency is not going to go away instantly... it will take 3 wet dry cycles to really get the stuff flowing around the plant again and the green will start coming back into the leaves that are starting to lose it. The burned areas will never come back, but the way you tell if the calmag is working is that you will first see a stop of the progression of the symptoms. Once you notice that its not getting worse, it will slowly start to get better. Keep chasing just one ghost at a time. If you suddenly make a bunch of changes outside of calmag and getting your pH correct, you are likely to cause new problems. Keep working this one... it will get better.

 

[Sam1992]

Think she's getting worse guys... 24hrs between pics... does anyone think she's gonna survive, looking pretty dull... no growth for 4-5 days.

 

[Growingasmile]

Think she's getting worse guys... 24hrs between pics... does anyone think she's gonna survive, looking pretty dull... no growth for 4-5 days.

Her new growth looks okay I would give it time, but you maybe right sometimes too much stress will stunt a plant and it can be a wash