My thought was that it is either caused by too much ppm or too much light. The taller of 2 plants is most affected.
I did a water change today and measured the waste water:
pH 6.6 (up from 5.8)
1200 ppm (up from 1150)
Is it normal for the octopot reservoir pH to rise that much in 1 week? Is this something I should try to be keeping down?
Since the ppms are higher than originally, I figured the plants had more than enough ppms to meet their needs… so I decreased to 1080 ppm this week.
Also… during last week’s water change I raised the light and increased it 1 level. The PPFD at canopy level read 790… which is pretty much where it’s been for the last month.
I took a new measurement today, and the PPFD was up to 940… quite a bit higher that at the start of the week.
Now I’m thinking that the light being too strong has probably caused the new growth to have burnt tips… especially since the growth closest to the light is affected the worst.
I turned down the light 1 level and the new PPFD is reading 750.
Hopefully any new growth in the next couple days won’t have burnt tips!!
Am I dealing with this problem correctly? Is there anything else to check for or adjust?
Your res nute mix is maybe too hot. I run mini octopots, and typically run the ppm at only 750ppm. I’ve found pushing above 1000 always causes problems.
Also, Yes. It is also typical for the pH to rise like that after a few days. Because the salts/nutrients sometimes lower pH. So as those nutrients get absorbed by the roots (and removed from the water), the pH will drift up.
There not much can be done to stop this.
Nutrient problem. I would have this using only fish emulsion. I assumed it was a deficiency because I only gave it the fish, and my little sodium vapor lamp was really not too much for the plant to handle.
Burnt tips are tricky because the reason behind of it is not so clear. Its often caused by sharp Ca ion breaking weak cell wall. So the question is what caused weak cell wall.
Often directly related to light and water uptake.
I know really majority of home growers connect tip burn to nutrient burn and stuff. That is not how scientists perceive about tip burn. Also, nutrient burnt is something that is hard to even define because it doesnt really exist. In fact, if you give high dosage of nutrients (high EC), it will hinder water uptake but thats not nutrient burnt at all. You only get nutrient toxicity by wrong nutrient recipe and if you use premade product (ex; plagron, canna, whatever premix) it’s slim to non you get nutrient toxicity.
And the most importantly leaf exist for photosynthesis and transpirstion.
Green part of leaf is for photosynthesis.
Tip burn is annoying because tip loses chlrophyll (green) structure and you lose photnsynthetic capacity. But as you can imagine, those tip burn area is less than 2% of total leaf surface. So, I recommend to dont even worry about tip burn😁 like seriously it doesnt even lose your producitivy noticibly, unless tip burn area is a huge fraction on the leaf area.
Hope my answer doesnt offend anyone but this is how plant scientist and horticulturist and biosystems engineer in horticulture often perceives about the tip burn.
