FOOD COLORING!!!!!!!! Stay away from the Fesser and probably the other one too. I had pink Fesser 1 and in less than 6 months it had completely and permanently stained the tubes pink. The particles which make it pink and uv reactive obviously do not dissolve in water. It also stained my XSPC Rasa 750 res/pump all my fittings had a coating of chalky pink residue. The micro channels in the block had some blockages and all the acetal on the inside of the block was stained with the chalky pink residue as well.
I have had NO problems with food dye it is dirt cheap and allows you to use distilled water. $20 for something that can't even keep it together for 6 months is crazy.
The reason I chose to buy Fesser 1 was because I was a NEWB and it said that it was non conductive. I do not think it stays that way but maybe someone else can comment on that. Distilled water is non conductive for a short period of time and I think that is the only reason they get to claim it is non conductive. I may be wrong but IMO it's all a scam.
If you like green you can use Ethylene Glycol to color your water green. It is toxic so it will keep any build up from happening. Silver Oxide is toxic as well and takes such a small amount it won't color the water so if you want a different color than green you can use silver oxide and food color.
There is a lot of debate as to whether silver oxide does anything in a loop and whether it does good or bad so read up and make your own decision. I use ethylene glycol.
Oh also if you want a nice aqua blue you can use blue food dye and ethylene glycol.
That is blue food color and ethylene glycol mixed with distilled water.
Making sure your entire loop is free from contaminates is also important as if the loop never had any contaminates it probably wouldn't grow anything anyways. But IMO you need to add something toxic. Ethylene Glycol also acts as a lubricant and a corrosion inhibitor I can not say the same for Silver Oxide.
I voted Koolance as in Koolance's Ethylene Glycol mix $2 for enough to treat 1-2 liters.Edited by givmedew - 2/18/13 at 1:03am