What is this?

I had septoria, that looked different. I think its Not enough Calcium

Hey Growmee … Septoria is a fungal disease that can affect cannabis plants. To cure it, you can try the following methods: Remove and destroy infected plants to prevent the spread of the fungus. Improve air circulation and reduce humidity in the grow area. Use a fungicide labeled for use on cannabis and follow the instructions carefully. Practice good hygiene and sanitation in the grow area. Avoid overhead watering and use drip irrigation or bottom watering. Ensure your plants are getting enough light and are not overcrowded. Check your plants regularly for signs of infection and take action as soon as possible.

Hmm, looks like fungal infection to me. Septoria.

To be honest, I've never seen anything like it... but it looks pretty ugly! Sort of like a very bad calcium deficiency but I highly doubt that's what it is. I've read through your diary and you've been having problems with several things so I'd just like to talk in general about your grow here. First of all, when you use RO water, you need to add minerals back into it because it has none, zip, nada and plants rely on those trace elements... and using RO water alone can bring about a lot of problems is you don't add those missing minerals back into the water. I don't think (don't see) that you've done this and it might be worth your while to read a little bit about using RO water when growing cannabis (it's usually used in commercial hydroponics grows - very little benefit using it in soil). Try this article as a start: ------------- "Do plants benefit from the use of a Reverse Osmosis water filter system? There are several factors to consider when utilizing RO water for cannabis. Water purification systems remove pollutants and impurities, making them safe to drink. But it also removes almost all of the water’s minerals, resulting in water with no mineral content. As a result, RO water isn’t “good” for your plants by definition. Because it’s so wrong when consumed on its own, it’s probably worse than regular tap water. However, what it does provide you is a place to start working on your solution’s nutritional balance. As a result, RO filters are often used in hydroponics since it requires exact and regulated settings. Soil purity isn’t as critical for growing crops since the soil performs most of the work. Poorly adjusted RO water, on the other hand, will do more damage than benefit. As a result, before pursuing the usage of pristine water, be sure that you have the necessary abilities, equipment, and energy to compensate for the loss. https://premiumcultivars.com/water-and-nutrients/reverse-osmosis-water-for-cannabis/ ----------------- I don't know what the solution is going to be for this grow - I'm tempted to tell you to flush with tap water that's been pH'd ... and to start your nutrient program over again but with tap water (or even Spring Water) ... As I say, I don't know what I'm looking at when I look at your pics here - but I think the underlying cause of what's happening is your use of RO water... Good luck...