noob with some questions, yellow spots and curling without using nutes

[MrJee]

My 7 White Widow plants have developed curling leaves that turn upward, and they have yellowing spots mostly on the edges of the leaves, some are completely burnt.

We are growing in homebox xl(120x120x200) with the whole tent covered in mylar(floor, ceiling,walls) with 6" inline fan and duct.

We are growing in bio bizz allmix soil, lights are on 20-4 and temps are around 29 celsius.
I do not think the heat is an issue, because it was hotter than this and they were fine, they have been growing about 3 weeks, and these signs started to show themselves about two weeks ago.

Then they were light green coloured spots in the middle of the leaves, now they look like this.
We have been ph adjusting our water down to about 7.0-6.5, due to 8.5 readings from our tap.
we have not started to use any nutrients yet.
humidity is at about 55 %.
Can too much ph down cause a ph imbalance and lockout of other nutrients?

I do suspect some of this is due to heat and maybe a little overwatering. my friend has been watering about every other day, but they have seemed fine before.
The plants have grown so fast, i had no idea they could become so big and bushy in such a short time, should i start to feed them now?

We have bio bizz nutrients series.

Ph levels of the soil is about 6.8.
Growing with a 600w mh, hps bulb for flowering when time comes, currently in 12ltr pots, lights were about 95centimeters away, but we moved them down to about 60cm today.

We are using General Hydroponics ph down, my friend said the runoff one day was 5.8 on one of the buckets, two days after the signs started to show, i read somewhere not too pay too much attention to the runoff ph.
They are still in veg state, not sure when we should start 12-12 and begin feeding.
Can this be a lack of nitrogen or maybe Cal Mag?
The big one has the most symptoms.

Please do not rip my head off since this is my first ever real grow, and hoping not kill my loved girls

Thank you for looking, any advice will be greatly appreciated

 

[Dr. Dank]

relax, they are fine, actually they look nice. You need to let your soil dry between waterings so stop your friend from constant waterings. Hes not helping. Heft a watered pot, feel the weight, when soil is dry, pot will be lighter, then water. Your PH sounds fine. Whats your water like?

 

[MrJee]

I have not tested the water alkalinity, but i suspect the water we have here is of good quality and might have a little higher cal mag than ro water since the ph levels normally range withing 8.0 and 8.5 from the tap.
No extra chlorine or anything, located in norhtern europe.
Just ph down the water for safety measure, is this a good idea or should i just use water straight from the tap?

 

[newbieharvester]

IMO this is the time for you to flush them good, then let them dry.....

 

[Zeltar]

Looking nice, the leaves will fix themselves just let them work at it

 

[MrJee]

so i have no reason to worry?
that is great, i really do not want to over react and do something stupid and make it worse, i guess some curling and yellowing is to be expected?

How will i know when i should start to feed?

 

[Zeltar]

Id suggest leaving it a week, (watering only once mid week) let the soil dry and then start, start out with 1/5 of the normal nute dosage and apply it every other watering, gradually increase the nutes with growth

 

[VerdantGreen]

ok, you are using an organic soil mix that (afaik) already has nutes/ferts in it. so you dont necessarily need to use more until your plants look hungry.

you are right,imo, to adjust the pH of your tapwater if it is as high as 8.5. but you cannot use regular pH down in organic soil as it may kill the microherd/soil biology that is needed to convert the organic ferts into plant food.
i use citric acid (you can buy it from ebay or you can buy canna organic pH down which is based on it) to bring my tapwater down to a good pH.

also you should let tapwater stand for at least a day to let the chlorine disperse as this will also kill your soil biology. also check that chloramine isnt used in your tapwater as this is bad.

plants look ok though.

VG

 

[MrJee]

but if my plants are ok, why do they look like that?

 

[bigwity]

overwatering overfeeding overloving. flush and let them dry proper before your next watering. then wait untill they need feeding so many people feed when they dont need to. they think the more food they get in the plant the quicker/bigger it will grow. i bet if most people half there nutes it will double the size of there plants

 

[MrJee]

we are about to start flowering, we will transplant into 19ltr pots and begin flowering the next week.
When can i tell when it needs to be fed nutrients?
We will be using mineral water (great bottle water,not the soda kind) with ph about 6.6 no added ph down or ferts from now on

 

[VerdantGreen]

the leaf margins folding upwards i have always associated with overwatering, and that also causes many imbalances.
flushing is fairly pointless with organics (as in putting loads of water through the soil) it will also make you soil very wet

the overall look of the plant is will tell you if you need to feed. if the leaves start to yellow then you should give it some extra food. yellowing from the bottom up usually means they want nitrogen (but you dont want to give it much nitrogen in mid-late flowering. yellowing of the tops often means they want more P and K (bloom ferts)
those are huge generalizations but a good starting point.

dont worry too much if the odd leaf dies back or isnt perfect - that happens.

VG

 

[G.A.66]

nitro is a mobile ellement so it can be deff anywhere on the plant, not just bottoms and they user more nitro and k in bloom than phos.
looks like ph to me. could be from to much watering.

"We are using General Hydroponics ph down, my friend said the runoff one day was 5.8 on one of the buckets"..think ya answered your won question here...
also i use 6.3 for soil. you also havent said ec/ppm level of food used.

 

[VerdantGreen]

yes nitrogen is a mobile element but when the plant starts to run short of nitrogen it uses up the N stored in it's leaves starting at the bottom of the plant - thats why plants yellowing from the bottom up indicate that N is running short.

they are growing in organic soil, so i doubt they are measuring ec/ppm and they havent added any extra food yet anyway over and above what was already in the soil.

 

[MrJee]

yep that is correct, we are not measuring ec\ppm and we have not startd to feed anything, we have just been ph adjusting our water with gh ph down, only a drop or two is sufficient for about 10litres of water.
can too much phosporic acid cause issues or ph imblance in the long run?
I will check on them today and see if they look any better, will check runoff of ph again and feed the largest of the plant .5 ml of biogrow to see if it makes it better.

thanks for your replys

 

[VerdantGreen]

hey mrjee as i said earlier in the thread, phosphoric acid isnt suitable for organic soil - you need to use citric acid. you can buy the powder off ebay very cheep and it will last you years (just put a tablespoonful in a pint of water and you have a bottle of organic pH down.

tbh i have never measured my runoff with organic soil. i just make sure what i am putting on it is a decent pH and let the soil/humus/microbes/roots do the rest.

 

[MrJee]

thanks for the advice, i have ordered powdered dolomite lime, and citric acid..should be good from now on i hopes.

 

[ibjamming]

thanks for the advice, i have ordered powdered dolomite lime, and citric acid..should be good from now on i hopes.

Just be careful...I mixed about 1/4 teaspoon into about 3-4 gallons of water and it dropped the pH by about a whole point...use SMALL amounts. At least until you get used to it. A little goes a long way...at least for me it did.

 

[VerdantGreen]

yeah, dont use the citric acid powder neat!

make up a solution as i described above and a few tablespoons of the solution will sort out a couple of gallons of water - a can full.

 

[G.A.66]

to be honest the realy arent that bad. a bit of droopy/sag. usualy waterings or room conditions cant transpire corretcly and does effect how it processes the foods, and the ph in the medium. i have the same thing here with this heat. tad slower growth and leaves arent reaching for the lights