Mephisto Grow - when to lower RH/is this calcium deficient?

[StankOfMyDank]

Hi all,

wondering when I should be lowering the RH in my tent? Currently on day 25 and I have the tent set for 75F/70%RH in line with a VPD chart.

also - is this calcium deficiency? I use reverse osmosis water and read that I need to start supplementing with CaMg each watering; and naturally Saturday (day 20) when I went to go water I noticed what looks like to be calcium deficiency. I messed up and used 1tbsp/gal (as opposed to the light feeding I was going for, 1tsp/gal, which is roughly 3x smaller than what I fed it). After another light feeding of CaMg on Monday I noticed yesterday that I still have yellow spots showing up.

I guess my questions there are
1) does it look like calcium deficiency?
2) could I have accidentally nute locked the roots with the 1tbsp/gal instead of 1tsp/gal mixup?
3) should I continue to feed light CaMg every watering?
4) will the spots on the leaves go away at some point or are they there forever?

thanks in advance! Also for extra detail - in soil with bio tabs. Just put in the tabs last Wednesday on day 17.

 

[namvet25]

Yes,keep using light doses of cal/mag at watering.

 

[KodakB]

The high humidity might be causing the calcium lockout. Try lower the RH% and watch for recover.

 

[Arthur]

Have you watered with plain RO? If so, that is the issue. RO is not something that can be used as a "stand alone" item. It must always be treated, either remineralized, or you can mix in a little tap. I run 4 gal RO to 1 gal tap.

RH won't lock out anything.... maybe if you held the plant underwater... but 75* 70% sounds pretty good (temps a bit low under LED) for anything not flowering, only risk to flowering girls is mold. Not something you want. Once buds are stacking, I'd bring the rH down some. Maybe 50ish. Maybe a tad lower.

Temp and rH in conjunction give us Vapor Pressure Differential, a tool that'll help a lot. VPD is the pressure differential between the rootzone and the air around the plant. Just like storms, things move from hi to low pressure areas.

Vpd allows us to adjust this pressure so things don't move to fast or to slow.

 

[Proph]

Hi all,

wondering when I should be lowering the RH in my tent? Currently on day 25 and I have the tent set for 75F/70%RH in line with a VPD chart.

also - is this calcium deficiency? I use reverse osmosis water and read that I need to start supplementing with CaMg each watering; and naturally Saturday (day 20) when I went to go water I noticed what looks like to be calcium deficiency. I messed up and used 1tbsp/gal (as opposed to the light feeding I was going for, 1tsp/gal, which is roughly 3x smaller than what I fed it). After another light feeding of CaMg on Monday I noticed yesterday that I still have yellow spots showing up.

I guess my questions there are
1) does it look like calcium deficiency?
2) could I have accidentally nute locked the roots with the 1tbsp/gal instead of 1tsp/gal mixup?
3) should I continue to feed light CaMg every watering?
4) will the spots on the leaves go away at some point or are they there forever?

thanks in advance! Also for extra detail - in soil with bio tabs. Just put in the tabs last Wednesday on day 17.

1. No. How can it be a deficiency when you been adding too much calcium??
2. Yes, very easily
3. NO...NO...NO.. and NO
4. No, they won't chang or go away. Autos do not have recovery time.

You need to read/learn about nutrients. How they work. What deficiencies look like etc. All the basic growing stuff. Calcium is immobile. Calcium issues start at the top of the plant and it spreads down the plant. Magnesium issue start at the bottom, and spreads up the plant.

I don't know how anyone can say to keep adding it when you haven't even mentioned what medium you're growing in. VPD has to do with getting optimal transpiration, which creates optimal nutrient uptake through the leaves and water uptake. All of these things factor in to how well the plant feeds. What medium are you growing in?

 

[Big Sul]

Was wondering same thing regarding medium. Also, have you fed them at all, or just RO water?

 

[pg2052]

@Proph - do you generally suggest to people not to use tap water given that it has calcium and magnesium in it? Just straight RO?

 

[StankOfMyDank]

Ok so a bit of varying advice here. Some saying use CaMg at watering, some not. I appreciate all the wisdom here.

I’ve basically backed off CaMg as I had potentially locked out the plant doing that. I ran a flowering compost tea recipe I saw in True Living Organics book by The Rev (diluted 1 gal of tea to 1 gal of distilled water) on Monday and gave it RO water with Hygrozyme and some pH up to bring it up to about 6.8 on Wednesday. Turns out that some of my issues were related to soil pH - clocked in at about 5.8 before the compost tea on Monday. I plan on measuring again tonight but still only plan to run RO/Hygrozyme/pH up until further notice (when the soil pH is back to about 6.2-6.5). Plant is still showing signs of deficiency, but thank you Proph for describing the Calcium and Magnesium deficiencies better than I’ve seen anywhere else. It seems like this was actually a magnesium deficiency all along.

People asked what medium I’m using - it’s Fox Farms Ocean Forest soil straight up with 2x bio tabs added at day 17 in 5 gallon Smart Pots.

I had a question now regarding my babies again - the leaves on #1 are curling down pretty significantly on new growth. Wanted to know if this is light stress? My HLG 320W XL is at 100% and about 14” away last night before I moved it to about 18”. Any other ideas at what it could be? Pics attached.

Also - does watering with Hygrozyme pHd up to 6.8 sound reasonable for the next watering or two? I think it might have been caused by essentially me overwatering, nute bombing with too much CaMg 10 days ago and not adding small amounts of CaMg with every RO feeding. Still not entirely sure what I’m doing (as this is my first grow, still learning every day!). Thanks again for all the advice. I definitely could use it! Just wanna learn as much as I can to treat these ladies right.

 

[Big Sul]

As I am still learning, I offer the following observations from a noob perspective. It is my understanding that OF is a Soil that has enough feed for 4-6 weeks for autos. The addition of biotabs at day 17 MAY be a little early which MAY contribute to the leaf curling.

 

[StankOfMyDank]

As I am still learning, I offer the following observations from a noob perspective. It is my understanding that OF is a Soil that has enough feed for 4-6 weeks for autos. The addition of biotabs at day 17 MAY be a little early which MAY contribute to the leaf curling.

Any and all advice is taken! Lol I thought that may have been slightly early - I’ve been following the Mephisto grow guide to start and they suggest around weeks 2-3, so I tried to split the difference there, but I think you have a good point. Next time around definitely waiting until halfway through week 3. After the bio tabs were popped in and I started to add CaMg the problems got significantly worse.