PH test solution inaccurate?

Hi Guys,
Im struggling with some seedlings, i have done my fair share of research and have every angle covered but it seems that i have nutrient lockout on my seedlings, could this be from the slight differences in PH'ed tap water ive been feeding them? I normally pour a cup of tap water let it sit for an hour. The solution test shows my tap water to be slighty green being 7, i then use some of the ph down powder to bring the water down to a yellow colour when tested being ph 6.5 and thats what i have been watering my seedlings with. Could this have caused nutrient lockout?
In the meantime i have ordered a digital ph tester to make sure its accurate.
Attached a photo of the PH up down kit.

I would get a brand name down and up not fish stuff.

There are specific acids to use to alter your ph during vegetative and flowering stages. I use a nitric acid based ph additive during veg and a phosphoric acid based ph additive during flowering. As the poster above said, i would get chemicals that are used primarily for growing.

you should not be feeding seedling any nutes just ph'd water.

H R Puff N Stuff said:

you should not be feeding seedling any nutes just ph'd water.

Click to expand...

Yup. They are too young for nutes. If you are using soil like Ocean Forest, it has plenty of what they need anyway. Green tap water at 7 ph is fine, no need to try to mess with it unless its way out of wack

I'm confused! I'm not using nutes that is a ph up down kit and I've been using the ph down powder to get my tap water to around 6.5, my question was as I only have a colour indicator test could the slight variations in ph be causing lockout?

That kit and its color chart is incorrect for growing