GSE flush to combat algae? First grow help

[cannablissx13]

So I've been noticing a lot of odd behavior in my babies (3 super lemom haze) within the last week or so, from discolored leaves, drooping, other odd little indicators of defiencies. Was checking ppms (water levels had dropped significantly as well as the ppms almost dropping by 100) and noticed some green in 2 of my plants roots. Newbie mistake with light contact with the 5 gal buckets im using.
They're coming up on 6 weeks old and i wanna attack the algae, and I've been seeing a lot about grapefruit seed extract.

So if i put in plain water to cut off nitrogen and phosphorus to the algae and supplement it only with the GSE would that be deemed safe? And if so how long should i flush for? Ive seen some posts say a week and others 2 days. I feel like a week without nutes would be an awful idea tho.

Or does anyone have any other suggestions to get me back on track?

They seemed fine one day and the next, depressed. Ive pruned the yellowing leaves and they otherwise seem healthy, just droopy. Im sure they're just getting screwed by the algae

Pictures provided were taken a day or 2 ago

 

[Chris Scorpio]

Natural light pics bud

Can't see crap with all the blurple

 

[cannablissx13]

Sorry about that.
These ones are the best i can get with my crappy phone. There have only been maybe 8 discolored leaves all together, and they've been pruned. But today I've noticed little specks of yellow closer to the edges of newer leaves on 1 and clawed yellow tips on the other. The 3rd is my fatty and shes just thick and droopy