Autoflower 17 days veg, brown spots on leaves

Hey, everyone.

I've been having a weird issue on the leaves of one of my autoflowers (Quick One from Royal Queen Seds). She's been growing in soil, supposedly a balanced NPK mix. As you can see from the pictures, this baby is getting weird brown spots in the middle of the leaves. I'm a newbie and this is my first growth, so I couldn't tell if anything else is wrong (except for her being a bit stretched cause of poor light conditions the first week).

I'm growing her in a 1x1x2m tent, 400W HPS. Fan circulating the air, temps are around 27C and humidity around 50-60.

Now I will say that I've been trying to correct a VERY weird issue with my runoff water. I'm using PH 6.5 rainwater and really didn't add any nutes as of yet (except for some tomato root bosters, but really only a 1/4 of what was prescribed and that was a week ago). Well, the runoff water is HOT AF. I'm getting up to almost a PH of 8 of my runoff water. I attributed it to the special green river pebbles that I added to the very bottom of the pot. I know they're full of minerals and that must be causing the runoff to be that hot, but is it possible this is causing these brown spots? I assumed the actual soil PH was around 6.5 (that's what the soil package says and that's my water PH as well). But the runoff is what's bothering me.

I tried to flush the soil a couple of days ago and maybe that's what caused PH fluctuations and did this? I have no clue how to plummet by runoff PH. It is hot as fuck and except for flushing, I have no clue what to do.

I suspect she's gonna start showing more and more problems the farther I go, exactly because of the PH issues.

What do I do? Do I try to flush again and try to drop the runoff PH or do I just let her go and see what she says in a week?

Thanks for the help, sorry for the wall of text!

Sorry for stacking up on the questions, but this is also bothering me.

One of my other autoflowers, day 19 Royal bluematic (from RQS), also is showing signs of something going wrong. I LSTed her to the side and she's doing fine overall, but the white markingsare showing up on the lower leaves and I have no clue what that is.

It started with what it almost looked like a cat scratch (left leaf in the pic) and then the very next day the whole middle of that right leaf expanded into that yellow/white spot.

What is that? I was thinking PH fluctuations again (same as the initial post), but I haven't done anything to this soil. This plant is using a different soil than what I described in my first post (no white river rocks and shit). It's a mix of starter soils, some coco in it too, peat, bottom filled with clay pebbles. PH going in is 6.5 rainwater. I didn't add any nutes lately and watered her 4 days ago. The soil is still moist a couple of inches down. She's on a 24/0 under a 400W HPS.



Thanks for helping out. Being a new grower on my first grow I'm at a loss. A tad shy of day 20 and I really don't wanna inject unnecessary nutrients in them or just do something stupid I might regret later.

Take chunks of soil from your pot in distilled water and check ph of that. If it's 6.5 then yes, the river pebbles are hot.

Edit: if the pebbles are only in the bottom of your pot.

Ivers said:

Take chunks of soil from your pot in distilled water and check ph of that. If it's 6.5 then yes, the river pebbles are hot.

Edit: if the pebbles are only in the bottom of your pot.

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Thanks! I never thought of that. I don't have a PH testing tool, but I did get ahold of the PH test drops. Will check the PH of the soil in the first post, definitely. Any clues about this second one? She doesn't have any river pebbles and still is showcasing something going on on her leaves.

I was hoping someone more experienced than myself would answer that for you, as I could leed you in the wrong direction.

Soil often contain nutrients for a plant to grow and thrive for 3 weeks. If deficiencies appairs at this point, I would start feeding.

Also i see the leaf stems are purple. If they are less purple/more green on the underside of the leaf stem, it could be result of a magnesium deficiency.
Magnesium def is very common in conditions where ph is off balance.
The spots can be calcium def.

I recommend getting a ph meter from ebay, they are not too expensive.

Hope this is helpful in anyway for you.
Good luck!

Thanks for chiming in again. I wouldn't know if my soil mix has appropriate amounts of nutrients, but that is definitely a possibility. Because all of the issues (on the two plants) started almost simultaneously. The mixes are different, but makes sense that might be the cause.

I will try looking into it a bit more appropriately after the next watering. Will try to reduce the PH a tad and possibly work off of that if it doesn't fix it. I was gonna hit them with a "scheduled" dose of nutrients on day 21, so hopefully that solves it.

Thanks again!