Whats the best record cleaning fluid?

On the advice of some of the contributors here, I purchased some Art du Son cleaning fluid and mixed up about 2 litres worth of the concentrate with distilled water.
I poured about a litre into my Raven RCM and stored the remaining litre in a clear plastic bottle sitting beside the RCM.
3-4 months later, I can see some largish amounts of grey/black 'fungal- appearing' growths lying at the bottom of the plastic bottle.
This sure doesn't appear 'kosher' to me and it indicates that the same contamination is sitting UNSEEN in the storage tank of my RCM.
Two questions :-
1. What could this be and why?
2. How do I drain the storage tank of my RCM and 'flush' out the 'growth'?

Halcro: What you see is bacteria / mold growth. Unfortunately, several posts on other threads have outlined these growths in that fluid. I do not know if it is a failure of the product or the water but the solution others have found is to put unused fluid in the fridge not in RCM storage tanks. I suggest you empty out the RCM any way possible . Use a solution of household bleach (10 parts water to 1 part bleach) to soak in the tank overnight. Clean, rinse and air dry the tank. In the future it maybe advisable to only "paint" each LP manually before cleaning to prevent a repeat problem. All the best.

Your container was probably not sterilized.

I don't understand this problem and why I don't have it. I no longer use L'Art du Son, but I have had a nearly full one gallon distilled water and L'Art du Son bottle sitting next to my Loricraft for over a year and have no mold. My Texas home does have central air and heat, of course, but mold does show up on food and other cultures in our house. I know that L'Art du Son does not contain any bleach given its goal to remove no vinyl when cleaning.

Is it possible that contaminated vessels or water were used in the first mixing?