Little advice needed please brown spots!

[hazeclouds92]

Strain - Barneys farm zkittlez og autos
# of Plants - 5
Grow Type - Soil
Grow Stage - flower
Bucket Size - 12L
Lights - (1) 600 Watt HPS
Nutrients - bio bizz grow and bloom
Medium - bio bizz all mix
PPM - unknown
PH - 6.2-6.5
RH - 50% to 55%
Room Temperature - 22°c-25°c
Solution Temperature - room temperature
Room Square Footage - 1.2x1.2x1.8m
Pests - None Known

Could anyone help in diagnosing what this issue could be? It has effected 1 plant of the 5 alot more than the other 4 brown rusty spots appearing on the leafs mostly on the higher ones receiving light.
Thanks

 

[Old Salt]

Because of the distribution of the spots on the leaf, I'd check it for pests, top and bottom, under strong magnification. If you see nothing, then look at possible nutrient problems.

Did the problem start with the bottom leaves and move up, the top leaves and move down, or appear everywhere on the plant at roughly the same time?

 

[Bush Doctor 77]

My first thought was critters. You can expect some fade in late bloom, but I don't think it's normal fade.

 

[hazeclouds92]

Because of the distribution of the spots on the leaf, I'd check it for pests, top and bottom, under strong magnification. If you see nothing, then look at possible nutrient problems.

Did the problem start with the bottom leaves and move up, the top leaves and move down, or appear everywhere on the plant at roughly the same time?

Thanks for your input, will check the plant tonight for any pests, what pests would cause the spotting like that?
I had a few gnats in the last grow but upon completion the tent and full room was bombed, fly paper out and the full tent and equipment washed with a bleach solution before starting these, not seen a single one since.
The problem started maybe 3 week after they started to flower I believe it started at the top and is working it's way down the plant, the leaves exposed to the light are the most effected.
Looking at pictures of deficiencys the closest I can find seems to be a magnesium/calcium issue, I'm in a hard water area and the plants have not had a flush since been potted into there final pots (5 week ago) could a build up of salts be causing a lockout for cal/mag?
Thanks again.

 

[Bush Doctor 77]

Thanks for your input, will check the plant tonight for any pests, what pests would cause the spotting like that?
I had a few gnats in the last grow but upon completion the tent and full room was bombed, fly paper out and the full tent and equipment washed with a bleach solution before starting these, not seen a single one since.
The problem started maybe 3 week after they started to flower I believe it started at the top and is working it's way down the plant, the leaves exposed to the light are the most effected.
Looking at pictures of deficiencys the closest I can find seems to be a magnesium/calcium issue, I'm in a hard water area and the plants have not had a flush since been potted into there final pots (5 week ago) could a build up of salts be causing a lockout for cal/mag?
Thanks again.

It could very well be salt build up. I like to flush with 1/4 strength nutes or water about once a month. I grow in peat/perlite, which some call soil, but it is not and I treat it like a hydroponic media. You say you have hard water. Do you dilute it with RO/rain to get TDS about 200ppm before mixing nutes?

 

[hazeclouds92]

It could very well be salt build up. I like to flush with 1/4 strength nutes or water about once a month. I grow in peat/perlite, which some call soil, but it is not and I treat it like a hydroponic media. You say you have hard water. Do you dilute it with RO/rain to get TDS about 200ppm before mixing nutes?

I'm pretty certain I have no pests in the tent but will have a real good check through all the plants tonight.
If I cant find any pests I will give them a good flush with plain water and see if that halts the problem.
I dont currently have a ppm meter so wouldnt know the measurement from the tap water, I feed very light due to not having a ppm meter generally 1/4-1/2 strength of recommended ratio, if ppms were too high would it not present itself as nute burn on the leaf tips?
I have a 100L water butt that collects rain water would it be better to use this rather than tap water?
Thank you for the advice much appreciated.

 

[MrSauga]

How high is the light? Some of those tops are cooking as you can see with the curled up edges. That rusting could be burning since you say it's only on the tops.
Whatever the issue is I'd raise the lights 6" to start with.

 

[hazeclouds92]

How high is the light? Some of those tops are cooking as you can see with the curled up edges. That rusting could be burning since you say it's only on the tops.
Whatever the issue is I'd raise the lights 6" to start with.

The light is a 600w hps that is a fair distance away probably at 30 inch or so from the canopy right now, the rusting is not just on the top it is also further down the plant on some shaded leaves, it is definitely alot worse towards the top though.
Thanks

 

[hazeclouds92]

Afternoon everyone!
Had a real good look over the plants last night couldnt find any evidence of pests anywhere within the tent or on any of the plants, pulled a few leaves to check under microscope still couldnt find anything!
Will flush tonight with plenty of distilled water see if that helps out over the week.
Any other suggestions?
Thanks.

 

[Bush Doctor 77]

Afternoon everyone!
Had a real good look over the plants last night couldnt find any evidence of pests anywhere within the tent or on any of the plants, pulled a few leaves to check under microscope still couldnt find anything!
Will flush tonight with plenty of distilled water see if that helps out over the week.
Any other suggestions?
Thanks.

Did you check under the leaves for critters?

 

[hazeclouds92]

Did you check under the leaves for critters?

Yeah checked both top and bottom of leaves had the full plant out of the tent to check thoroughly! Nothing to be found
Thanks

 

[Old Salt]

I thought spider mites as the damage they cause is very like what you have.

With the problem starting with the new leaves, and moving down, I'm thinking a magnesium or manganese defficiency. These can be locked out by too much calcium.

 

[hazeclouds92]

I thought spider mites as the damage they cause is very like what you have.

With the problem starting with the new leaves, and moving down, I'm thinking a magnesium or manganese defficiency. These can be locked out by too much calcium.

I've had them little f***ers before(2 crops ago)! Absolute nightmare to deal with! I had read they can lay dormant until the right conditions return for them to thrive, so again after that crop was done, everything was thoroughly cleaned with a bleach solution and the full room and tent smoke bombed, had no issues with them on the last 2 crops. Certainly know what I'm looking for with them little pests!!
Magnesium has been my "guess" from the start, I have a feeling the soil is full of salts from the hard water out of my tap! So my next step is to give all of them a really good flush I have a big rain water collection tank I'm thinking of using the water from that rather than the tap or bottled water... anything I need to do with it before dousing my plants in it?
Thanks in advance
Really appreciate all the input from you knowledgeable people!

 

[Old Salt]

Not that I'm aware of. Just flush slowly with three time the pot volume.

I've got four 275 gallon totes behind the house for rainwater collection when spring arrives.

 

[Bush Doctor 77]

Hard water comes in 2 types, basic and acidic. I live in the western high desert. We have hard water that is loaded with Ca/Mg. Back east I had hard water that was acidic and loaded with iron. I mix my 350ppm hard Ca/Mg water with RO/rain to 200ish. I never add Ca/Mg, and the only time I had a problem was when I increased the RO/rain to well water ratio.

200ppm water is used to flush and for mixing nutes. I never use RO/rain for either.