Variable Storage Tank - Strange Odours

I have a stainless steel tank of 150L that is a variable capacity system that has a floating lid which is then sealed with parafin oil (200ml) to create a permanent seal. There is then a lid that fits on the top of the tank to act as a dust cover.
This is the first time I have used this system. I recently filed the tank to 100L leaving about 30cm (1Ft) space to the underside of the lid.
After about 2 weeks I checked it but have found that there is an odour from the top of the vessel that resembles a stale acidity. I have since cleaned the area of any spillages in the hope that this goes away but I am not confident.
What could be contibuting to this smell or odour. The parafin oil should provided a permant seal around the edge so that there is no exposure of the wine to air. I am concerned as I thought that this system would be better that the small glass demijohns that the wine was originally in.
Any thoughts please ?.

I may not understand your system correctly, but it sounds like you installed things incorrectly and the wine has oxidized. The lid normally seals with an inflatable gasket and rests directly on the wine, not a foot above. You generally lower the lid to the wine (that's why it is called a floating lid). You pump the gasket up to create a seal which protects the wine. A foot of space above the wine is way too much and is a certain way to allow it to oxidize.


Please advise us if you have some other type of system.

You may have some off-gassing of the wine coming past the parafin oil collecting between the floating lid and the dust cover. Any CO2 collecting there will make the air in that space smell stale.

Hi appleman, this system has the floating lid directly on the wine which floats on top of it. The gap between the wall ofthe container & the rim of the floating lid is taken up with the parafin oil. The lid (1Ft above) is mearly a dust cover.

Thanks PeterZ. Is this a bad thing & will it affect the maturing process of the wine.

Maybe you can leave the lid ajar to let these gases out but still keep dust out of there.

I don't expect that the gasses building up in the head space will be a problem. They are coming out of the wine. Just air out the head space periodically.