Plants aren't doing good.

Hi guys, my plants aren't doing good. I am in coco and my PH is 7.2 which I am struggling to lower because every time I add PH down the PH rises back to 7 after a few hours and from the research I have done it is due to the buffers in my tap water which is stopping me from lowering my PH. So that is my first problem. Another problem is some of my plants are looking okay and some are looking yellow, almost like they have a nitrogen deficiency which I am struggling to correct. I'm mainly focusing on any new growth and it is coming through green which is a good sign?. My E.C is 1.5 and temps are between 27c and 29c. I can provide pictures if needed. They are under a 600watt HPS at about 28 inches away from the canopy. They are around 5 weeks old. They started to turn yellow when they became root bound in 1 liter plant pots at 4 weeks old. Maybe that is the problem for the yellow and droopy growth? They seem to be doing a lot better than they were but it seems like I am still struggling along. Any help is appreciated. Cheers guys

I think my only option is to either switch to normal soil which likes a PH of around 6.5 - 7.0, or use RO water which doesn't have buffers in the water and then add calmag and stuff back into the RO water after I have corrected the PH?

I'm just trying to provide as much information as possible. Some of the new growth has very small rust spots on some of the phenotypes. But I don't think its rust mold or whatever it is called. I think it's a deficiency??

I am growing a mac-1 hybrid by in house genetics. It is called s"MAC"kin. And from what Capulator said on his instagram before it was deleted, he said mac-1 is 100% indica and the plants seem pretty small from there age. I am guessing that is because it is either a mostly indica or 100% indica strain? It is crossed with Pancakes by cookies and I know that is mostly indica due to it's ridiculously dense buds? So I'm guessing they are small and short due to the genetics? I know that in flower they triple in size, as most strains do.

I'm not a coco guy but I know they like a ph down around 5.8-60 so you are way off base. You have to ph your water much farther down and if that's not working then you're going to have to use ro water from the store or get a home RO water filter kit to filter it at home. Your plants would definitely benefit from a transplant into bigger pots I'd imagine at this stage at well, pics would help. Try using some mycos product to help stimulate the roots that are bound up to spread out and get moving. The yellowing is because the ph is so out of whack they can't uptake nutrients most likely, compounded by possible salt buildup in the small container and root bound plants. Fix the ph issue and give them a bigger pot and they should green right up. Hope this helps. I also think in Coco you need to water multiple times a day but I'm a soil guy and hopefully some body with more Coco experience can chime in.

Pics will help.
A Ph of 7 can cause issues in coco. 5.5-6.5 is considered ideal. With coco there should be little to no buffering. I don't ask this often because I don't check mine but what is your run off Ph?

FirstCavApache64 said:

I'm not a coco guy but I know they like a ph down around 5.8-60 so you are way off base. You have to ph your water much farther down and if that's not working then you're going to have to use ro water from the store or get a home RO water filter kit to filter it at home. Your plants would definitely benefit from a transplant into bigger pots I'd imagine at this stage at well, pics would help. Try using some mycos product to help stimulate the roots that are bound up to spread out and get moving. The yellowing is because the ph is so out of whack they can't uptake nutrients most likely, compounded by possible salt buildup in the small container and root bound plants. Fix the ph issue and give them a bigger pot and they should green right up. Hope this helps. I also think in Coco you need to water multiple times a day but I'm a soil guy and hopefully some body with more Coco experience can chime in.

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Small rust spot on the leaf, droopy slightly and looking slightly yellow

Old growth yellowing. I believe it is a nitrogen problem, But I don't know how to fix it The new growth is coming through green so maybe it is okay? or is it taking the nitrogen from the bottom and feeding it to the top due to a lockout? I don't know.

Not looking the best, the new growth is coming through green but the old growth is yellowing off. And yes I am about to feed the plant next to it, I know it's dry I have been trying to figure out the problems all day

The rust spots are usually magnesium deficiency brought on by either lockout or ph imbalance so high the plant simply can't uptake the nutrients. What is your humidity level? Your temperature is on the warm side. You'd have to be pretty humid to have a decent VPD number for young plants.

FirstCavApache64 said:

The rust spots are usually magnesium deficiency brought on by either lockout or ph imbalance so high the plant simply can't uptake the nutrients. What is your humidity level? Your temperature is on the warm side. You'd have to be pretty humid to have a decent VPD number for young plants.

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my humidity is about 55 - 60%. It was about 70% but I lowered it slightly as they grew older, is this right?

FirstCavApache64 said:

The rust spots are usually magnesium deficiency brought on by either lockout or ph imbalance so high the plant simply can't uptake the nutrients. What is your humidity level? Your temperature is on the warm side. You'd have to be pretty humid to have a decent VPD number for young plants.

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Yeah I think it's a lockout. When I make a 10 liter watering can up and lower the PH. it rises after a few hours again after testing the PH of the water in the watering can. I hope this makes sense?

Mix your nutes. Ph down. Feed em.

coreywebster said:

Mix your nutes. Ph down. Feed em.

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So as soon as I PH the water, feed them straight away and don't worry about the PH drift?

Are you up north or down south?

OK, these charts are invaluable to me.

And I'm a little confused, you mix your nutes and then let them sit? Why? If your solution sits stagnant there is a good chance of fallout when the nutes settle. This could cause Ph fluctuations.

harrychilds said:

So as soon as I PH the water, feed them straight away and don't worry about the PH drift?

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Yeah. Just add your nutrients, stir well.
Check ph, adjust accordingly and feed

Johiem said:

OK, these charts are invaluable to me.

And I'm a little confused, you mix your nutes and then let them sit? Why? If your solution sits stagnant there is a good chance of fallout when the nutes settle. This could cause Ph fluctuations.

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I get a 10 liter watering can, add 10 liters of water out of the bath tap. Let it sit for 24 hours to get rid of the Chlorine. Add my nutes and then add PH down. I get a reading of about 5.8 - 6.0 PH and then let it sit in the watering can for another few hours and check the PH again. And it's back to 7.0 - 8.0

coreywebster said:

Are you up north or down south?

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Down south dude

Yes, I've had that happen and it's really frustrating. I can't claim to understand the science of why it happens but it's something to do with the amount of buffering agents in the water. I'd try getting the water down to 5.7 and seeing how it does. 5.8 is fine for Coco and going a little lower to let it ride into the sweet spot shouldn't be a problem. If not I'd hunt for a different water source and do some experimenting with the ph of it. Getting the ph right is critical in hydro and Coco so stick with it, you'll get there. I grow organics and don't have to check ph at all, it a very easy style of grow. Mix in dry amendments in the beginning before planting and then a couple of top dressings during my flower that I just sprinkle on. The only thing else I do I just water them and maybe add some epson salt if I see magnesium deficiency in veg. Super simple and all organic which I like.