Large fan leaves yellowing and dying. First grow.

[Osirus]

SOIL GROW

Strain - Big girl is Northern lights/indica hybrid , Little girl is Unknown.
# of Plants - 2
Grow Type - Soil
Grow Stage - Vegetative
Bucket Size - 5 Gallon
Lights - (1) 600 Watt MH
Nutrients - Bio thrive 4-3-3, only fed once at (1) tsp per half gallon in its life Jan 13. One watering before transplant into 5 Gallon.
Medium - 15% Perlite 85% Happy Frog Soil.
PPM - Unknown.
PH of water given - 7.0
Run off PH - Big girl 5.0 , Little girl 6.0
RH - 50%
Room Temperature -74°- 78° day , 66°-69° night
Solution Temperature -Unknown, room temperature.
Room Square Footage - 4x4x8
Pests - None Known

Problem: Leaves of big girl are yellowing and dying. After I added the nutrient I noticed the pH run off of Big girl dropped to 5.0, little girl was 6.0 and unaffected by the nutrient. I only had a half gallon of water at the time so I put (1) tsp to half gallon. Recommended light feeding was (2) tsp per gallon, so I just halfed it. Jan 13 was the first time I ever tried nutrient and this is what happened.. I do believe the pH is just way too low and it may be locked out. Any suggestions? I hear happy frog is a very acidy soil. BTW I only have the drops to measure pH so I just use whole decimals. Also I did a transplant Jan 16 into 5 gallon, watered with plain 7.0 water. Now just waiting for next water to correct pH.

 

[KingJohnC]

You want pH 5.8 for hydroponic and soiless (peat moss and coco coir) and pH 6.5 for soil. I would flush your plants with pH 6.5 adjusted water until the runoff pH is the same as the input pH. Your leaf problems appear to be from a nutrient lockout.

here is a nutrient availability chart

 

[Osirus]

Thank you for the quick reply. Would you suggest i do a flush right away or next watering? I just watered 3 days ago, so its still fairly wet.

 

[SweetLeef]

Hey Osirus!

Fear not, for you are in the hands of good KingJohnC! I'm gonna send you good vibes and see what happens

 

[KingJohnC]

Thank you for the quick reply. Would you suggest i do a flush right away or next watering? I just watered 3 days ago, so its still fairly wet.

I would flush your plants now if the yellowing is progressing fast.

 

[Osirus]

I figured the potential hazards of nute lock out are worse than over watering. Thanks for the advice, ill try it and post a follow up. It does seem rather fast.

 

[Osirus]

Hm.. No matter how many gallons of 7.0 (light green) i pour in it, the ph wont go any higher than 6.0 (bright yellow). Im on gallon number 20 and this is only a 5 gallon pot. It did raise it from 5.0 to 6.0 though.. Should i try adding a buffer after this soil dries out next watering?

 

[KingJohnC]

You could try to add a buffer to your nutrient solution next time you water or top dress. Do not use baking soda as a buffer, it contains too much sodium. Just make sure you continue to water with pH 6.5 adjusted water.