What ppm meter did you get? And a question because I didn't know how important ppm could be until recently. Let's say your water is too high or too low at 338. How do you eben go about changing that to where its supposed to be?
There is no too low for ppms. RO water is zero or near zero ppms. Too high depends on what is in the water. 338 ppms of what?
My well water is high. Above 300 I think. Hard water. But it's mostly calcium. For me, it doesn't make sense to pay to RO my water, take out the calcium and then pay to put the calcium back in with calmag. For others it makes sense in Hydro or to take out additives like chlorine.
It just depends on what is in the water and what your grow environment is. At least, that's my take on ppms.