I actually recommend keeping water level up to net pots all the time. After a day or so water level will lower due to plant drinking it, and evaporation. You will need to top off every couple days with ph'd water, and make sure you neevr top off more than the original amount of solution. So if you use 6 gallon buckets; you use around 4 gallons of solution. You can top off with up to, but not more than 4 gallons. Doing this does 2 things; It helps to keep a build up of salts in the rez from happening, and saves you money on adding fresh solution all the time. Process of fresh solution should be done every 7-10 days.

More often than not In veg when plants are small you would use the longer 10 day solution schedule due to plant not feeding as much. In flower; You may have to change solution in 7 days or less. *

* In DWC plants tend to get big. Especially if you use a big HID (1000watts) In this case sometimes you will go through the 4 gallons of solution and 4 gallons of top off ph'd water in less than 7 days.

Good Luck.

Good to see you around Loc Nar. Peace