1/4 of my plants drink 3/4 of the water

So, this has been happening lately.

I have four 360-degree hydro systems, each with 14 plants.

One of the systems is using hard water, the rest soft R/O water.

The system that uses hard water has been taking 40L of water every day, for about 14 plants, while the other 42 take around 15L.

The temperature and humidity are basically the same and they're all in the same room.

The hard water system has been doing pretty crap so it's not a big issue as I'm not likely to continue using it, but I'm still curious.

Any ideas?

Same strain in each of the blocks? Three times the transpiration rate begs for some external source.

Don't worry about it.

Not all lifeforms feed the same.

Just make sure they all get enough and all will be well.

More Ca in the hard water system makes it easier for the plants to take up other nutes & in doing so more water is taken up as well.

Just a guess.