Yellow Spots - Cal mag?

[olegren]

Hi, everyone. I'm back. Have been keeping my grows going while braving the apocalypse and trying to stay productive with work + school. The distractions help me not lord over my plants so much, but I'm concerned I might've been a little neglectful. My older grow is looking really rough; while the newer one seems to be developing problems similar to those the older one displayed early on. I thought I had a rust/fungus problem, but now I'm wondering if this isn't actually cal mag. Please see form below:

Problem: I'm seeing some small yellow spots on leaf growth. Some leaves are developing bright green/yellow tips as well.

Medium/grow method: Soil: FFHF+FFOF (66/33) with 25% perilite mixed in

Feed: and supplements used: None. Soil only.

water source: Well water PH'ed to 6.3-6.5

Strain/age: Northern Lights Auto (South Oregon) - Today is day 28

light used: 260W QB (Currently pushing about 14k lux at canopy) ~ 200ppfd on a 20/4 schedule

Climate: Last week's average temp was 79.74 F. RH @ 51.7%.

Additional info: This little lady is my third grow. She's sitting next to the second, which is about 2 weeks ahead. It had similar problems and is now looking pretty rough. I'm wondering if this isn't a cal mag deficiency based on some useful videos in the stickied threads here. I've heard a lot of people recommend cal mag supplements for QB lighting, but our water is heavy in both so I had not bothered. Definitely not over watering. Based on weight, she doesn't seem to need more than 16 oz or so in a week at this stage. I mention this only because the symptoms could fit with under watering, but again... weight seems fine. Even if the soil up top feels bone dry.

Worried that this was fungus, I also disabled my humidifier. Previously, I had it maintaining 60% RH inside the tent and exhaust running 1 min on / 4 mins off. The last couple days, average RH has been closer to 35% which I realize is very low. That seems to coincide with the onset of this, so maybe I have simply traded one problem for another?

I'm also including a photo of my second grow -- which displayed similar symptoms early on. She's looking super rough now. Wondering if this isn't the same basic problem in a more advanced stage, but I am way out of my element at this point.

Thanks in advance for any guidance!

 

[OttoCBD]

Have you tried adding cal mag? To me, it seems kind of risky to trust that your water source should have enough of both. I'd try half strength of any kind of cal mag to see if that does the trick.

 

[olegren]

Have you tried adding cal mag? To me, it seems kind of risky to trust that your water source should have enough of both. I'd try half strength of any kind of cal mag to see if that does the trick.

Not yet, but I think I'll grab a bottle and see if it helps. Couldn't hurt, right? We had a water analysis done not long ago, but actual quantities in regards to cal/mag were not in there -- just that it was high in content. Not unusual for this area. Our water is pretty hard.

Thanks!

 

[AutoWonders]

Pic #3 looks like it's on its way to a potassium deficiency. That will need to be double checked as deficiencies are not my strong suit. When I switched to Autocobs and Quantum boards, I've had less cal/mag problems compared to my old led lights.

 

[Waira]

two glaring issues: lack of feeds and that damn lousy Fuxfarms soil! I'm betting the pH is off as well, contributing to the problem,.. OF is the #1 problem soil I see in here, and I have tested many bags in the past; all were badly off pH, acidic form crappy composting and undercooking,.... not much to do but feed them, but even that's a risk... feeds are acidic, and if the soil is too, matters will worsen... You need a soil pH probe to check in-pot pH, a lot hinges on that... the Accurate 8 (CPW) soil pH probe is a good unit... This will determine if the pH is off and locking out what little nutes are in there,....
Last alternative is to do a flush, 2-3x pot volume; test pH occasionally and stop when it get in range again, about 6.5.... be sure to add 1/4 nutes on last pour through to restone what's been stripped by the flushing ....

 

[olegren]

two glaring issues: lack of feeds and that damn lousy Fuxfarms soil! I'm betting the pH is off as well, contributing to the problem,.. OF is the #1 problem soil I see in here, and I have tested many bags in the past; all were badly off pH, acidic form crappy composting and undercooking,.... not much to do but feed them, but even that's a risk... feeds are acidic, and if the soil is too, matters will worsen... You need a soil pH probe to check in-pot pH, a lot hinges on that... the Accurate 8 (CPW) soil pH probe is a good unit... This will determine if the pH is off and locking out what little nutes are in there,....
Last alternative is to do a flush, 2-3x pot volume; test pH occasionally and stop when it get in range again, about 6.5.... be sure to add 1/4 nutes on last pour through to restone what's been stripped by the flushing ....

@Waira - Thanks. I have been wondering about this myself. When I first started down this road, I got really into a thread on RIU where a guy swore by FFOF. He had a lot of grows where he was pretty much using that and only that, top dressing but adding nothing else.

That all said, the guy did admit that he'd heard their quality could vary pretty wildly nation wide. With other variables like light, water, and environment locked in, the list of potential causes is getting smaller and smaller -- soil being one of them.

I have a couple seedlings sitting in some happy frog right now. I'll go read about some other soils to try and maybe give one of those a shot when it's time to transplant in a week or so. Thanks for weighing in.

 

[OttoCBD]

As of late, FFOF is known for their free fungus gnats with every bag.

 

[Mustang92]

I'm onboard with Waira, i've had ph problems and drainage problems with the fox farm soil I've used this year. I'm usually to cheap to pay for FF but had some given to me. I'm now mixing it with promix and extra worm castings because I don't trust it anymore and I'm to frugal not to use it. I don't own a Accurate 8 (CPW) soil pH probe (thinking i need one) so I usualy check the run off once a week if it has FF in pot.

 

[Waira]

....yeah, it does seem very hit & miss with them. Local sourcing and manufacturing differences likely... When the first came out, they had hills and heaps of composted lumber waste to tap into, and it was good soil all those years ago,... Now it's long since depleted, they are many times larger, and from what i see, running on their old rep'... The soil is cheap too, comparatively, but that comes with quality drops! I find hands down, a few extra bucks per bag is well worth it!
Roots Organic original is still pretty good, fairly readily available,... Royal Gold King's Mix is my current fav', very light, a true soil (RG is mainly a coco/blend types)... My best mix is with Sanctuary Soils Empire Builder and KM, 50/50... The EB add some heaviness, water retention to it, hearty's it up some! I use the EB for outdoor photo's. Problem is, Sanctuary soils are not easy to find unless in CA....
Anyway, OF was never meant to be a "water only" soil, not even sort of,... What's that guy top dressing with?
If you want that type of TLO/LOS soil, look into SoHum and KIS.. KIS has a great Nutrient Pack that you can add to home made soil and cook for a bit, making "water only" soil... But even they say some mild supplementing especially during bloom will have better results, and you must use bigger than usual pots to make sure you have the supply load to last the grow,... Otherwise, you'll spend as much on shipping as you do the RTU bagged soil!

Get a soil pH probe, a good one like the A8... pH is so critical, even with great soil if it goes out of range it won't matter how good it is! Locked out nutes are locked out nutes...

 

[olegren]

Thanks, everyone, for sharing your insights and wisdom on this topic. I guess that is part of this process for me -- Figuring out what I picked up early on that works and what doesn't.

@Waira - The whole spiel was that he used nothing but FFOF. The premise was FFOF and only FFOF. Top dressing with the same. I did see him mention, later on, some other soils he liked to mix, and given seedlings/transplant concerns, FFHF was a top layer in many formulas. Thanks for calling out some other favorite brands. That was going to be my next question. At the end of the day, I don't mind using whatever works best -- Just want to do it right. I don't even have an aversion to liquid nutes. Rather, I bought into the idea (early on) that there were "simpler ways" that avoided the potential pitfalls of doing nutes wrong. I am pretty good at doing things wrong when it comes to growing.

I'll invest in a soil probe. If you don't mind me asking: If I were working with something like Roots Organic or another available in my area -- Is the idea that these soils are lighter and therefore you follow typical nutrient vendor guidelines and schedules with them? (While monitoring PH of course. I have been doing so for my water; but took for granted that this soil self-regulated)

And, as a quick edit -- Is this the probe you fine folks are referring to? Amazon product