yes (liquid test?) or aquarium ph testers you can buy at your local pet store. I'm not at all sure if this is the issue or not.......hydro growers love ph and we cherish knowing it.

Things like underwatering, overwatering, heat stress, too many nutes and root disease issues can all cause a plant to wilt badly so it's pretty hard to say.

Ps....DONT use pool OR pet ph ADJUSTERS to change ph......fish ph up and down is too high in salts and I would seriously doubt anything you'd put in your pool would be something you'd want to use in growing.

You can use distilled white vinegar to lower ph and baking soda to raise it.....in an emergency only. You want ph between 6.2-6.8, going both in and out.

I'm asking about ph because of what appears to de a def in the one plant.....with the yellow edges.......but could be the wilted plant's problem as well.....although I have a feelng that the two issues are seperate.

Good luck.