AaylaSecura

That's what I feared. Thanks for the reply

It happened less than a full day after I put the dye. It's not like the PC is in front of the (glass) door, facing it, but I guess the Sun does hit it in the morning. I can try to put a bit more dye, not use the CCFLs, and cover it during the day to see if this will happen.
 
Hmmm given that I only put 5-6 drops of dye I wouldn't expect clumps but I guess it's better to flush it sooner than what I had planned for the first maintenance.

Yes, I noticed some of the paint coming off and I regretted getting painted fittings... Once I have everything connected again, I will simply disconnect the inlet of the reservoir and put that tubing in a bucket, the keep filling water into the reservoir -> and run it for a minute of so to flush the whole loop; then connect the output of the last block back to the reservoir inlet and fill it up. Should do the job.

@Faceman
 
My original intention was to build a completely custom water cooling loop that includes the CPU adn the GPU, but since this is the very first time I'll be using liquid cooling at all, I am reluctant to experiment (especially on such expensive hardware). So I decided to go with an AIO and from your words I recon it'd be best to get the Nepton 240M and leave the GPU with its stock coolers. When I have the time and money I will sure try to build a custom loop and will definitely go for a custom one for my next build whenever that may be.
I think I got what I needed for now, thank you again for the help!