Day 17 Flower: Fan leaf discoloration

First time poster, long time lurker. I am just getting back into growing after a few year break. So far, all has been relatively good with my 3 plants (OG kush from seed, star tonic clone, and blueberry clone). However, just in the past few days (day 15-17 of flower) the blueberry plant has begun to develop some browning on the fan leaf edges (see pics). I have looked around a bit and saw some similar posts, but most that I came across were more of a yellowing issue. I was hoping to get a few opinions on what could be going wrong. I'll try to give as many details about the grow as possible...

Medium: roots organic soil (haven't been very impressed with this stuff, will probably go back to ffof). 5gal containers.

Lighting: 600w HPS (6" blower for exhaust/cooling) and 4x Cree CXB3590 3000k (passively cooled, added day 1 of flower). I rotate the plants every 1-2 days.

Nutrients: BioBizz line: bio-grow, root juice, and bio-bloom. I try to feed every other watering. I started in veg with the root juice and bio-grow at 1/4 dose. Had some deficiencies in early veg but these went away as I started to ramp up the dosage per feeding. For flower I started with a 1:1 ratio of bio-grow:bio-bloom, then to 1:2, and most recently 0.75:3.

Water: Tap. I do not know the ppm unfortunately. As for pH I only have the strips and do not test every watering, when I have tested in the past it seemed to be between 6.5-7.0. Next watering I am going to record pH going in and coming out. (I will be investing in some better water testing equipment next grow for sure)

Temp/RH: Lights on: 75F 44% RH Lights off: 62F 50% RH
Late veg / early flower I was having a problem with low temps (57F) and high humidity (85% RH) at night. No PM thankfully. Leaving the exhaust fan on at night has seemed to solve the problem for the most part.

This plant has always lagged behind the others when it came to watering. It takes an extra 2-4 days to dry out. Not sure if this is just the plant or if I should have added perlite to the soil. The other plants seem to be doing just fine though. There has been a time or two when I watered it lightly when it didn't need to be, because I was short on time / wouldn't have the opportunity to do it the next day. Could overwatering cause this discoloration?

I have probably forgotten to include a few things, please let me know if more details are needed. Any thoughts or opinions would be greatly appreciated!

Hmmm...

http://www.growweedeasy.com/phosphorus-deficiency-cannabis

Good Luck and Great Growz

Thank you for the link! The plant is showing a handful of symptoms listed on that page. I am going to give it a flush, then hit it with some more bio bloom, and try to get the nighttime temps up a bit. Hopefully that will help out. Much appreciated

Adjust your water ph to 6.3 for soil, or soiless in flowering, if not your locking out magnesium witch then locks out others since its a mobile nutrient.

Lower humidity to 30% 40%

Keep the veg nutrients going for the first 2 weeks into flowering if using a 1 or 2 part fertilizer

Add some magnesium and or cal mag combo with the added benefit of having nitrogen to keep them greener for the extra demand they require going into the stretch and the magnesium to sustain the leafs.

Too much calcium locks out magnesium

FLBD said:

and most recently 0.75:3.

Click to expand...

This should only happen once (if ever) in the period between the end of week 5 and the end of week 6

High P is not needed in container gardening

and it is the early switching to bloom nutes and boosters that cause what you are seeing

Thank you for the replies. Should I have not been giving any bloom nutes the first couple weeks of flower? Or just less than what I was?

No bloom nutrient formulas for the first two weeks while into flowering, keep using your vegetation nutrients.

The reasoning is that the plant is still in vegetation mode into early flowering and still requires vegetation nutrient ratios until the plant has slowly transitioned fully into flowering for at witch time it's demands change in favour of the higher P & K nutrients.