Reverse osmosis wateris nearly pure water with a PH of 7. Reverse osmosis is a filtration method that removes more than 99% of all the contaminants in water. The result is nearly purewater, which which has neutral pH of 7. But if it's exposed to air, RO waterdrops down to an acidic pH range of 5
Stick with what you have for this grow and upgrade when you get more experience. The lights you have now should do fine. Don't expect more then a dried ounce from each auto
I'm just letting you know the humidity range that seems to work best for me, Everyone will be a bit different. The higher humidity will cause it to dry slower, which is a good thing. So if you want to keep the rh higher that's totally up to you
I checked the specs on the light, they are not great but will do the job. You can use 1 light at 18-20" away for the first 7-14 days then add the other light.