yellow tinting on leaves?

Since I've put the NFT system on the plants have shown some good growth, I'm slightly worried that the leaves seem to be developing a yellowish tint, at the tips and edges. I've heard this could be a few different things, I dont think it's overwatering (since its in the nft system i hope not)

Each of my tanks are 9 gallons, I have a CF reading of 6, a ph of 5.5 and have placed a little oxygen in the tank a few days ago.

Here are some updated pics, any advice will be gratefully received ;)

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It might be too wet, or it might be ferts...

Im no good with hydro

Yellowish leaf ends generally mean to much nitrogen. HOWEVER, I am only familiar w/ soilless growing. I know some of the babes I used to grow would start out w/ yellow leaf ends and gradually go greener.
Water temp also turned out to be a problem that was difficult to solve.
Keep Posting! I wanna see how yer girls turn out! :)

Use a minimum amount of nutrient in this early stage. I prefer only root stimulator in this stage

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Originally Posted by MrGuy

Yellowish leaf ends generally mean to much nitrogen.:)

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thats strange, I always found that yellowin leaves was too little nitrogen.

Yeah I had heard the same thing..... Guess I'll just leave them and see how they go.

yellow spots have been showing up recently on two of my plants too (ima first time grower, indoor, soil)
i have read that it was because of too little nitrogen as well and just gave them some nutrients (12-6-6 to start em out, i heard when you start feeding 20-20-20 is ideal, but i wanted to start out smaller since they are only two weeks old and 7 inches tall)
ill let you know if the yellow spots go away in a few days (hopefully)

happy growing

thanks dude, what's your cf reading?

I've got them at 8 but dont know whether to push them up, some of the tips are a little yellow but most of them are a great green plush color. I think maybe I fert'd too early but they catching upto needing it now.