Brown spots with yellowing areas

[DaveR1974]

Problem: Brown spots with yellowing areas

Medium/grow method: 3 Gallon fabric pot with Biobizz Lightmix

Feed and supplements used: From BioTabs.nl - Week 1 :
1 - Startrex mixed in Soil
2 - 5 grams of Mycotrex in transplant hole (germinated in Jiffypot)
3 - 1 Gram Bactrex and 5ml Orgatrex in 1/2 litre filtered water
Week 2 :
Added 1 BioTab
Week 5 :
1 - Added 2nd BioTab
2 - 1 Gram Bactrex and 20ml Orgatrex in 1/2 litre filtered water

water source: Filtered tap water

Strain/age: Seed Stockers Northern Lights Auto - Currently day 43

light used: LED - FECiDA 50W LED Sunlike Full Spectrum (300W CFL equivalent) - 18/6 light cycle - Approx 40 cm/15in from canopy

Climate: Ambient temp 23C Night, 25-27C Day. RH 50-60%. Day 40 saw spike in Day temp to 32C

Additional info: Started grow in Space Bucket ( Log ) First noticed the spotting Day 37. Day 39, noticed tops of plants only few cm from light and unable to raise lights, so day 40, transferred to Grow Tent.

 

[draxcel]

Hi,not a doctor as I have problems too,but it looks like some sublte deficiency or lockout Maybe.I'll post a link in some minutes
As promised,here


I use this video when not sure to have a first diagnosis

 

[blue]

Looks to be a CalMag def .. rusty spots.
Most likely caused by the filtered water having the calcium filtered out of it.

I would try using gassed off tap water (leaving the water with lid off to gas off / dechlorinate) .. assuming that your tap water isn't the worst type of hard City water in the UK .. the Biobizz lighmix should do a good job at buffering the PH into rage for you.

 

[DaveR1974]

Thanks. I'm in a soft water area, so I will stop filtering.

I thought the BioTabs were supposed to supply all the needed nutrients, hence I was filtering to get rid of the Chlorine.

What kind of change should I notice and how long until I notice do you think?

If the unfiltered water does not work, I know I can add Epsom Salts to combat the Magnesium deficiency. What could I use to combat the Calcium deficiency that is organic?

What should I do about the leaves with the spotting? Prune or leave them until they fall off, or will they repair themselves?

 

[draxcel]

I think they Will not repair,but,they will store energy and do photosynthesis so keep Them and if they fall off it's ok.

 

[Deke]

Calcium from egg shells. Or just get a bottle of cal mag it will last a long time.

 

[Waira]

BioTabs includes a PK booster, either the liquid PK or the dry tea stuff, and it's essential IME with this product!
I see P defc. straight up.... large patch necrotic patches is a pretty classic P defc. symptom, so is the weak bud setting....
The Tabs are more N rich than anything which is why they recommend using the PK boosters for best results. Late inclusion of that last Tab isn't going to really help with this, but is likely needed for all the other nutrients, though i dislike the amount of late N input that will bring....

Your best bet is to get some PK booster in there ASAP, their stuff, or whatever you can grab! Avoid rock phosphate, it's too slow to release, you need right-now PK, guano's are fastest I think but weak on K usually, so keep that in mind...
Roots Organics offers HPK, 0-4-3, liquid bat-poo basically, and a good PK ratio too....

 

[DaveR1974]

Thanks.
I need to wait until the weekend to get some form of PK booster, as don't have the funds at the moment.
The Roots Organics range is not easily available where I am, but I think I've found an alternative from BioBizz (Bio-Bloom), but I notice it has N too (NPK of 2-7-4). Do you think this would be okay?

In relation to the late inclusion of the 2nd tab, I was following BioTabs own instructional video for Autoflowers. I take it you would recommend following their standard instructions for future grows instead?

 

[DaveR1974]

Calcium from egg shells.

Good tip, though it will take time to save up enough eggshells, and they are slow release. I will remember them though to add to my soil mix for a future grow.
I have since found that I could use Gypsum (not the wall material) which is readily and cheaply available form Home Brewing stores.
1 tablespoon of Gypsum (Calcium phosphate), along with 1 tablespoon of Epsom salts in 1 gallon of water. Cheap and easy (like me) CalMag.
Dosage - 2ml per litre of water

 

[Daipot]

Looks to be a CalMag def .. rusty spots.
Most likely caused by the filtered water having the calcium filtered out of it.

I would try using gassed off tap water (leaving the water with lid off to gas off / dechlorinate) .. assuming that your tap water isn't the worst type of hard City water in the UK .. the Biobizz lighmix should do a good job at buffering the PH into rage for you.
Most definitely