Indoor Rust spots

Jul 22, 2021
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Hi all,

First timer here! I’m on about week 4 (end of) and have been noticing some rust spots. I had some about 2 weeks ago (literally one or two little but new growth from there seemed okay, maybe a bit bright green on one plant but soldiered in anyway. Now my other plant (the one without the supporting bamboo stake in the photos) has developed some. They both get fed the same, using Biobizz nutrients in coco/perlite mix with calmag each and every water (have been following the Biobizz nutrient schedule).

I have also noticed today that some of the leaves have been curling inwards so I moved the light to 24” (from 14).

I thought it could be caused by the PH level of the feed I’ve been giving them ( was around 6.4ish - now around 5.4 upon reading that actually when using coco this should be where I’m aiming for)

Anyone got any ideas ? I’m also really struggling getting the RH down below 68-72% have put a dehumidifier in there and it’s made almost no difference at all, so it could be a combination of things but would like to know what to pinpoint. Should I just flush with plain water for a week or so and see how she goes ?
A few things: They look over fertilized. Are you fertigating to 20% run off every day that you fertigate? Are you using ALL of the nutrients in the Bio-bizz schedule.

What is the source and PPM of your starting water?
Hi Man, Thanks for replying to me again !

I haven’t been doing that previously, running until run off- I’ve been giving about 1L each 3/4 times a week and up until now they’ve seemed okay with it, with only a few drips of run off in the trays underneath though.
today I have flushed with 2.5L each of plain water @6.2 ph - runoff measured 6.7 / 6.6 .
Whole time I’ve been using bottled drinking water from local supermarket. Every time I water I’ve been giving them nutrients so I’m giessinrg that’s where the problem stems from.

I dont have the whole Biobizz range (only three I haven’t got are fish mix, root juice and microbes) but I haven’t been using all of them anyway.
I’ve only just really started with top max, alga-mic (only as foliar spray so far) and activera in the past week. I just received a bottle of bio-heaven though so will start a little bit of that once they have dried off too.
Biogrow and calmag I’ve been using since the start and Biobloom was at Around 3 week mark. Almost been following their schedule exactly, I’ll add a photo in case anyone else reading wants to see it.

The PPM of the water I’m using (before nutes) is 0085? Seems quite low to me but I’m not sure how accurate my pen is, it was a proper cheapo one from eBay. In all honesty I haven’t been checking the ppm as I was told in another forum by a couple of people not to worry about it if I’m using a growing medium, and that it only really matters for hydro ‍
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I must say though, even since flushing a little bit this morning before work, the one that has the most rust has grown about half an inch and is looking quite perky already!