Heating oil tank (plastic) has rusty coloured layer on bottom... Problem?

[DIYNotIan]

Hi

The tank is around 7 years old. Any ideas what causes it and/or whether it is a problem?

Sorry the photo is not great, it's the best I can get through the small opening.

Many thanks

 

[ChrisJP]

Since there is presumably nothing within the plastic tank that can rust, this layer of rusty material must have come from the oil deliveries. This suggests that the oil merchant has steel tanks with water layers at their base and that rust formed from this is being dispersed into their oil. May be advisable to change the oil supply merchant?
As long as the rusty layer is not disturbed it probably won't do any harm. If it's disturbed enough to get into the oil take-off pipe (which is located a little bit above the base of the tank), the filter on the offtake pipe will catch the rusty particles, but could clog up fairly quickly, necessitating removal and cleaning it - not a big job but tiresome nevertheless.