I’ll see if I can find the meter that I use which I believe others to use as well. Although that looks similar to mine except mine is blue. Should work, maybe.
Do NOT toss it out… lol seriously, you will get some smoke out of it. It’ll be better than nothing. Log what you learn. It will come in handy on your next grow. You’ll be ok. Just heed the advise of others.
Are you on any kind of light schedule?
When you switch to 12/12, she may double in size.
Temp of the water and lighting also plays a big roll in the development of the plant.
Get the light in check.
Get the temp of the water In check.
Get the nutes in check.
Get the PH in check.
Get the environment in check.
Get the air movement and air stones in check.
You’ll be off to an awesome grow.
After you finish this grow and you want to take it to the next level, we can guide you through it.
Let us help you get through this one.
You got this!