Possible Corrosion in my loop? [Question]

[Jrjy3]

So I found a potential problem in my loop, and I was wondering if any of you could offer advice. 

 

I was topping up my loop today and I noticed that the copper cap on my reservoir was discolored. I thought that it could have been some gunk or something that built up on it, but after wiping it off, it appears to be corrosion. The picture below isn't that great, but I don't have a better camera, so it's the best I can do.

 

I'm using a CoolerMaster Glacer 240L pre-filled loop as my pump and first radiator (which is all copper) along with an additional Alphacool all copper radiator. The GPU has an EK copper waterblock, and the reservoir is an Alphacool res with copper plugs. 

 

I have a silver killcoil in my loop, and I also used some copper sulfate as an additional biocide. 

 

Because everything in my loop is copper, I didn't think I would need anti-corrosive, but should I add some, or is the stuff on the plug not corrosion? If I should add anti-corrosive, what would you recommend I use? I know anti-freeze works, but I've heard it gunks up easily. 

 

Additionally, is there anything I should do with regard to the GPU block or CPU block? Should I disassemble them to check for corrosion? (And if I should, and there is corrosion, what should I do?)

 

I know there are a lot of questions, but I greatly appreciate anybody's help!

[Jrjy3]

Flush and stop using copper sulfate for a while. The copper used in some parts may not necessarily be pure copper.

 

I built my loop around a year ago, so it's probably time to replace the liquid anyways. However, the only time I used the copper sulfate was when I built the loop, so it doesn't seem like it should be a problem. Either way, I'll flush it and see what happens. Thanks for the advice!