Maybe leftovers of previous setup. Try cleaning everything up. Also make sure the water you put in is well distilled, and that the bottle has not been left open too long, or exposed to sunlight. Leave hot water (even slightly hot, +2°C over ambient) at contact with air, and algae and bacteria will settle there in no time.
I've been using distilled water + redline (and nothing else), and vinyl tubing continuously for 8 months now, without any trace of deposit showing up.
I'll get rid of vinyl tubing soon though, those cannot stand turns - even *light* turns. They tend to pinch or become 'flat' after time.
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