New DIY ATS build for 120g

I have found that electrically speaking, the reds are more sensitive, meaning, if you zap them with intermittent current like a bad connection that jumps a gap, they blow easily and all in series. On my first MCPCB I had SMD jumpers that were not always good connections from the reflow machine (Steve's LEDs mounted components for me) and if one of these was loose and you bumped it, it would go on/off/on/off very quickly and zappo all the reds are gone. The blues would eventually, but they seemed much more resilient overall. By the time I switched to violets I had the problem solved with the loose connections so I guess I really don't know the answer for sure, but my gut tells me that they are at least as sensitive.

The blues I was using were 1000mA rated Philips, driven at 700mA you might expect better resiliency to intermittent currents. So logically the violets, rated for 700mA just like the reds, would blow easily.

Overheating from repeated soldering will do in an LED rather quickly actually...especially if the iron is too low or too high.

If too low and star PCB is mounted, you have to hold the iron on for a really long time or result in cold joint = solder could pull off pad in future
If too hot and star PCB mounted, this can work but if you hold for too long
If too hot and unmounted, you can fry it if you hold too long so you just have to get used to the timing
If too low and unmounted, you this can work OK but can result in a cold joint = solder could pull off pad in future
If removing connections, you want to de-solder if you can, but at minimum add more tinning before adding the new connection

The key is to have the iron hot enough to flow solder on to the pad for tinning in like 1 second or less. Then let it cool a bit before going to the next pad or soldering the connection. If it's on a heat sink, hotter iron is OK but still have to move fast.

 

That's typical progression, you probably want to wash away the dark growth but not too vigorously. Use slow running tap water, room temp and swip each side once with the palm of your hand, then if you still have a lot on there rub with your fingertips (gently). Leave all the strands on there (the ones that remain) and let it run for another 10 days.

Dark growth usually means high nutrients, not enough light, etc, but I'd say it's too early to judge. Don't change lighting at this point. What do you have it set at?

 

I would keep that going for another cycle and see what it looks like in a week or so