Hillsborough Leisure Centre expects to re-open to swimmers at 9am on Wednesday morning (5 March).Operators Sheffield International Venues closed both pools at the centre at midday today (Tuesday) following a leak of harmless carbon from the filtration system into the two swimming pools. Staff noticed a slight discoloration in the water following a routine filter change and immediately asked 20 swimmers to leave the water.Tim Hicks, health, fitness and operations manager at Hillsborough Leisure Centre, said: “We can confirm after contacting the manufacturers that the carbon is harmless. The pool water is now being filtered overnight to return it back to its crystal clear condition. We hope to have the pools operating as normal from tomorrow morning. The rest of the centre is operating as usual.”Anyone wanting an update on opening times should contact Hillsborough Leisure Centre on 0114 231 2233.