Dwc Roots and topping off

[Johhnyblaze44]

I have 2 femanized grand doggy purps in two 5 gallon dwc buckets. Im using GH 3 part flora series. My ph is between 5.8-6.2. They are about 28 days from seed. When i changed my res i noticed the roots started to has a discoloration to them. They werent as white as before. I noticed it the day after i changed my res. heres some pics


Roots





Heres a picture of that plant



Is this root root/slime or am i just being paranoid?

Hers the smaller plant in the dwc. Its about 4-5 days behind the other one. I have yet to change the res on this one and the roots are still white




Hers that plant




Should i just not change the res?

When topping off should i just add tap water and ph the res?

 

[Hydrosun]

I top off with PHed nute solution. I also very rarely change the contents of the veg system, just keep adding more nutes. Every few months or so I'll drain the system and start with 100% fresh nutes.