Three Weeks Into Flower And Brown Patches And Some Yellowing On Leaves

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Aug 13, 2018
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Ok my friends. I have a Wedding Cake S1 and a Green Crack sharing a tent. So far I haven't had a single issue and they are growing great.
They are into their third week of flower and I am noticing some brown rust like patches and some random leaves turning yellow. The rust patches do not wipe off onto my finger and the bigger ones are all crispy and crack. I have checked for any signs of bugs with my 60x loupe and there's no signs of bugs whatsoever and it is an indoor grow in a tent.

My temp and humidty have been perfect the entire grow and it doesn't appear the growth has slowed or halted.
I haven't been Phing my water as I don't have a device to do so but when checked on my last grow with Ph paper it was bang right.

I'm growing in Canna Terra Pro soil under two LED lights, one being Meizhi 300w Cob and the other 2000w Vander LED. I'm using Biobizz Grow, Bloom and Top-Max nutrients and have been giving them half doses.
It appears to have the problem on the older bigger leaves rather than any of the new growth.

I am using a Co2bomz device for Co2 and an oscillating fan on the plants. My extraction fan is definitely too weak as it is only a weedy 4" one.

Tomorrow I am going to order a Ph and EC devices so I can keep an eye on that side of things in case it could be a lockout or nute build up.

Not sure whether I should wait until those devices arrive or act now but I fear if I act now I could do the wrong thing and make it worse.

Thanks in advance guys.

I would like to know if you have been watering with tap and if you have been supplementing any cal mag?
Hi and yes straight tap water that I believe when tested with Ph paper on my first (completely failed) grow it was about 6.5 and other than the biobizz nutes I haven't added anything at all so no cal mag.
You for sure need to get the ph meter. If your tap water was acidic (less than 7) your pipes and fixtures would be severely corroded. So im guessing 6.5 is wrong. Most tap water is in the 7.5 to 8.5 range. Add in some cal mag. The next time you water preferably, you can also foliar feed at a low dose.
biobizz website faq's say ph'ing isn't necessary. organic nutes generally feed the microorganisms that in turn feed the roots/plants. the faq's also state that if your water is <200 ppm disolved mineral content, you may need to add calcium and magnesium. it suggests dolomite lime or epson salts(magnesium only) for that. another thing is tap water isn't necessarily always the exact same water. depending on what your town or city is doing to the water(ie-extra chlorine, recent flushing of the pipes, etc). chlorine or chloramine can kill the beneficial organisms in the soil so if you can, let the water sit out for a few days to allow it to evaporate. also, the plants look kinda droopy. are you watering them enough or too much? you should water them until you get some runoff. i let my plants sit in the runoff for about a half an hour to allow the soil to soak up as much water as it can then let the soil dry out to the point where the top is dry down to about one knuckle deep. top max looks like it makes ca, mg etc more available to the plant so maybe any of those micronutes that were in the soil have been exhausted.
I think my water schedule is right as I do water until I first see run of and then I stop and I always let it dry out until the top is bone dry and down to the knuckle it just falls off of my finger. I'm going to order the meters tonight after midnight when I get paid and then I can know for certain what my waters ph is so thanks guys. I was half guassing the ph to be 6.5 as I was using that cheat ph paper so it could really have been showing me anything at all.
I do feel (and this is just going on feeling the energy of the plants) that it could well be a cal mag issue and as I would like to try keep it all organic I'll go for the epson salts and dolomite rather than a liquid cal mag.

So first job will be to test my tap water and run off as soon as the devices arrive and then I'll post back and see where to go from there. Thank you guys.

I will add that in the other secion of the tent I have a blue cheese auto that is well into flower now and only looks to have a few weeks left and I haven't had a single issue with her at all, she's been an absolute pleasure to grow. I will upgrade my extraction fan though as soon as I can but one worry I have is that it will just suck straight out the co2 that the co2bomz squirts out but I can't see how to avoid that really unless I set the timers so the fan only comes on when the lights are out and the co2bomz isn't doing its thing.
Another quick question, what organic thing can I use to add the calcium if I am going to have to get a cal mag suppliment? I'll grab some that you mentioned for the magnesium but what about calcium?
i use general hydroponics camg+($20 on amazon for a quart, lasts me about a year and i am a small grower). i never check my ph(i use general organics biothrive but i am sure what you are using is fine). messing with the ph in organic grows is not recommended unless you have some really high or low ph water. ph is important when using chemical fertilizers. i screwed up a couple of grows when i switched to chemical nutes because i was used to not checking ph. i have never use co2 but my understanding is that it is only efffective at pretty high concentrations and higher than normal temperatures(85 degrees comes to mind). different strains have different nutritional needs which is probably why your auto is ok. bone dry is not a term or a practice i would recommend. my soil about an inch down is not dry but not moist. feels like soil fresh out of a bag of good soil. letting it get too dry is not good. you could kill your microbes off that way too. the lower leaves are going to be junk any way so you needn't be too concerned. i think another member here is a big fan of foliar feeding with dilute GH Micro. maybe she will chime in here. she knows her stuff a lot better than i do but i think you and lesso are right in thinking cal/mag deficiency.
and the epsom salt thing is from on the faq's page. i have never used it. i would be wary of the other recommendation of dolomite lime in flower since i think lime is high in nitrogen.
I use Epsom salts in my garden to stabilize the soil. When I use tap water I don't ph it but I have and it always runs around 6.5 to 7.0, which is ideal. You will learn a lot more by ph-ing the runoff water from your grow. As for the Epsom salts, add 1 tablespoon per gallon to every 3rd watering. The first indication of a magnesium deficiency is red stems on the leaves and red streaks in the stalks. Then the leaves get funky veins and start browning out. You should add it even if you do not show symptoms as it promotes nute uptake.
If you are concerned about ph you could always top dress with some dolomite lime.
I had read that for the most part with an organic soil grow it's not something to really bother about but I will but the testers just so I know what the Ph is up to and also how much salt build up I have in my soil.
So let's say it is a cal mag issue, am I to flush and then start my nutes from scratch including the cal-mag stuff then as well? I don't feel it is a major problem and it's early enough in flower to catch it in good time so thanks my friends, I'll keep you posted.
Just add the calmag or Epsom. Calmag is used in water gardens 'cause they got no other way of getting calcium. Epsom is used in organics 'cause they already should have calcium, which is a trace element to begin with.
If you need to flush a soil grow you really messed things up. I don't think you are there yet.
My bad. Dolomite lime doesn’t have nitrogen. Looks like it has calcium and magnesium. Sounds like it is not quickly available though...
Ok guys I have just ordered a Ph and an EC meter so I can keep a better eye on my tap water and runoff etc to make sure I'm not heading for a lockout and I'm thinking if it is a cal mag issue which from what you are saying it sounds like it is would you recommend going for the dolomite lime (I can get it on Ebay cheap enough) which I have read takes a while before it starts to work or just go ahead and buy some cal-mag even though it isn't organic and I was hoping for a full organic grow if possible? I guess I would rather address the problem quicker even if it means my grow will no longer be 100% organic.


That looks to be the European version in the link you posted from ebay. I don’t think you need to get it urgently if it is only affecting the lower leaves. I know it is easy for me to say since they are not my plants but if you get it in a week I think you’ll be ok...
That looks to be the European version in the link you posted from ebay. I don’t think you need to get it urgently if it is only affecting the lower leaves. I know it is easy for me to say since they are not my plants but if you get it in a week I think you’ll be ok...
I've ordered a bottle so hopefully it shouldn't tale long. My stems are all purple or have purple lines running up them as well. Deffo seems like a cal mag issue, thanks guys.

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