4 different strains, 2 having problems

Im doing my 2nd grow in coco and since ive started feeding them one plant started to yellow about a week ago, i flushed it and 2 days ago another strain started getting yellow tipped leaves. There is not much sign of improvement since i flushed it and i will post some pics as i dont know if it could be a defficiency or them being nute burned any help would be appreciated




two of them look healthy one is real bad at the back left. the worst one is a Top69, there aint much info on it as it pretty new strain, the other im starting to have trouble with is the Kush at the front right. The NL and white russian are doing well and they in the same medium on the same feed, so im confused to what to do

What is the Ph?

it was 6.1, i only have a test kit and nothing to change ph with?

I dont really have any cash to buy ph control stuff straight way as i jacked my job when first crop arrived, is there any way to change it using household goods, i dont think its the ph but i will need to learn how to control the ph soon so it on my shopping list.

Im not sure if its nute burn or deficiency that causing yellowing. It should be nute burn as it happened on first feed, only used qtr strength feed aswell, im just worried as it was flushed maybe 6 days ago and still no signs of recovery, and now the kush has yellow tips

The others will soon follow, get some pics with the light off ,cant see with those ones.

sorry couldnt post last night, here is some pics i took with the lights off...



as you will notice i cut off the worst of the yellow bits last night using sterilised scissors. i not sure whats happening, if you can help would be appreciated

hmmm...I would back off the concentration a little, and try to let them get drier inbetween waterings.

I'm with misnu there, i admit to knowing nothing bout coco, but that looks like clssic nute burn to me. One tip tho..Ya might try getting just one strain dialed in. Some strains have widely different nutrient requirements, I really have respect for those able to pull off multi strain grows, epecially in hydro or a hydro-like environment!!

Yeah i will try that misnu thanks. Jack i just trying to find a strain thats easy to look after that why im trying different strains, you will notice in first pics one plant is doing really well so i will be buying more of those and work on just one strain at a time in future. this multi strain buisness probably aint the best idea for a newbie like me but i do my best and hopefully learn how not to overfeed and stress the plants to much.

I thank you both for your time. If i could ask one more q... What if the yellowing gets worse should i flush them again or stick to giving them low doses of nute.