Indoor Yellow/brown spotting on seedlings

[Exivious]

These are 12th day seedlings in coco. No signs of mites or any insects. Temps have been around 78-80f for several days with RH 70-75% and good air circulation. I didn't notice the spots while watering earlier today, but 6 hours later. When I finished watering, some droplets splashed on the leaves. I'm hoping this caused burning on contact, but that may be a bit of a reach...

More info in my journal starting here: First Grow - 4 Different Auto Strains in Coco

 

[Exivious]

Another spot I just found:

Could this actually be early stage calcium deficiency? I decreased CalMag a few days ago by 40%.

Oh please let this be it. I will raise CalMag immediately.

(This is a direct cross-post from my grow journal--sorry!)

 

[Exivious]

I think I've successfully diagnosed this one and am on the way to rectifying it. I guess we'll find out in the coming days. Because the largest audience on any forum is the people who will find threads via search engines many years down the road, I want to make another cross-post from my journal in case it helps someone else in the future:

Why did you lower calmag?

There was some logic behind it, however misguided. I first started reading about growing just two days before biting the bullet and ordering all my supplies (about five days before germinating). My baseline early on became the ultra-conservative growweedeasy guides. They recommend a lot of traditional stuff like 'only feed nutrients every other watering' for coco. I thought since I was feeding daily, perhaps I would back off the usual CalMag dose just a little to avoid an accumulation of calcium toward the end of the grow. It would appear it might not accumulate in the substrate to the extent I had anticipated.

I'm about 95% sure this is the problem now. I'm going to do a light late feeding tonight to bolster calcium levels.

Edit: I just re-fed, this time with a hefty dose of CaliMagic. Day 10 is when I decreased from 5 mL to 3 mL.

 

[namvet25]

Are you PH'ng your water?Coco is known for having PH problems so this is very important.Your intake water should be around 5.8 to 6.

 

[Exivious]

Are you PH'ng your water?Coco is known for having PH problems so this is very important.Your intake water should be around 5.8 to 6.

Yep. My filtered tap water is 6.5 so I add a bit of acid. I've been using indicator drops and feel pretty good about them down to 0.5, but last night ordered a pH pen. For the increased CalMag last night and throughout today, I used a bit less acid hoping to get close to 6.2 to increase calcium absorption till the issue is dealt with.

 

[namvet25]

Yep. My filtered tap water is 6.5 so I add a bit of acid. I've been using indicator drops and feel pretty good about them down to 0.5, but last night ordered a pH pen. For the increased CalMag last night and throughout today, I used a bit less acid hoping to get close to 6.2 to increase calcium absorption till the issue is dealt with.

I'm not an expert on coco but I have used it and found it is very hard to regulate ph and therfore more problems seem to happen.As far as those spots on the leaves that could be due to water spots and not any defiecency.