Does RO water wash away nutrients in the soil?

Is your tap water bad? Why are you using RO water? If it is not needed then don't use it. RO has most everything stripped away which means you need to add some minerals/nutrients back that would otherwise naturally be in regular water. For example, the two main minerals in my well water are calcium and magnesium which is beneficial to my plants. If I were to use RO water I would have to add those nutrients back into the water... essentially undoing what the RO filtered out. But if your water isn't the best then RO is a good baseline to start so you know what is in your water.

No, unless you open tap of RO water for few days and do super flushing ;)))) Not the best way to water your girl if you go in soil, but a must for pro level if you go in any other growing medium. All the Best !

No, RO water will not wash any nutrients away faster than tap water or any other type of water, unless you are drowning the pot of soil constantly. There should be enough goodness in a pot that size for 3-4 weeks depending on soil quality, otherwise start feeding with half strength nutrients once she has 5 pairs of leaves/5 nodes.

RO has a higher aggressiveness then tap water does. This is from the lack of mineral content causeing it to be corrosive to anything that can be ionized in water. Eg metal, this is why RO water always uses plastic bladders and pipes. The RO water would leach out nutrients if you where watering and producing a lot of run off. but this would also happen with tap water that has a lot of dissolved minerals in it. RO would just do it faster IMO. If you watering and no runoff is happening your fine.

I’m not sure I understand? Using RO wouldn’t wash nutrients away any different than tap really.. You’re fine.. if you have good soil you shouldn’t need to feed nutrients for probably a month or more.