From Silvana:

Pool cleaning during the state of emergency

Following a number of enquiries it is confirmed by the Officer in Charge of Environmental Services of Mazarrón Town Council that, on health and safety grounds, ALL Pool cleaning Companies can continue working (one person only, at any one time) in order to maintain water quality. However, this should be done whilst safeguarding the workers and the clients’ safety, therefore fewer visits combined with a higher degree of water attention could be considered, in order to minimise unnecessary journey and reduce any danger of contamination, whilst achieving optimum pool maintenance and avoiding problems with mosquitos.

According to the World Health Organisation (WHO) to date, there has been no evidence to suggest that the new coronavirus could be spread by mosquitoes. The new coronavirus is a respiratory virus which spreads primarily through droplets generated when an infected person coughs or sneezes, or through droplets of saliva or discharge from the nose

However, COVID-19 being a Novovirus (New virus) this is not proven.

Mosquitoes can spread other diseases including zika, malaria and yellow fever so WHO still suggests taking steps to prevent bites. Wearing light-coloured, long-sleeved clothing as well as insect repellent can keep you safe outside and you should also be sure to remove any stagnant water so mosquitoes aren’t tempted to breed there.
Washing your hands and not touching your face are two ways to reduce your chance of contracting the respiratory illness.

People must maintain the chemical balance in their pools to prevent mosquito breeding, U.S. disease control figures estimate an average-sized unmaintained swimming pool could produce more than 3 million adult mosquitos in a month, there are also health risks connected with swimming or splashing in an unmaintained pool including Legionnaires disease and other unpleasant illnesses, it doesn’t need to be a registered company as long as the chemical levels are maintained, some years ago Mazarron Council were the first to introduce legal requirements for swimming pool water quality,and fines ranged between 300 and 3000 euros, the Council use Lokimica Laboratories SA to control pest spread which includes flying drones over properties looking for green pools.