A SGSP collects and stores solar energy all over the year being the storage zone designed in a way that the summer stored energy can be used during winter [7]. Temperatures in the Storage Zone can range from some degrees above ambient temperature to values reaching 100 °C, depending on the Solar radiation available in the region and on the design of the storage zone and thus are appropriated for a wide range of applications. In this work we will focus in Aquaculture facilities.

In fact, the decrease of natural catches and the increase of fish demand as a food source, led to a growing interest in intensive aquaculture. In Portugal, Aquaculture growth, in the last decade, with an hundred farms providing 5% of the total consumed fish. Portugal is also the European country with largest per capita consumption and one of the highest in the world, with an annual average consumption of 60 kg/person.

In order to build a Solar Pond the basic conditions are the union of three factors: good solar irradiation good access to salt (typically NaCl but other available salts can be used) and existence of water. In the presence of these conditions the initial cost of construction evolves basically: excavation and waterproofing of a basin and the installation of some kind of heat extraction device. In a second phase the pond must be monitored making it possible to measure salinity and temperature gradients and the state of the Pond in terms of transparency to solar radiation. Those measurements will allow to predict the beginning of instabilities in the gradient zone allowing consequently its reposition. It may be referred that the basic destabilizing process in the gradient zone is the diffusion of salt which is a very slow process which in fact is the reason why solar ponds actually work. However the presence of the opposing temperature gradient can give rise to double diffusive instabilities and from time to time maintenance operations are necessary to correct the salinity gradient to values well above the critical values for the start of instabilities [8].

These corrections can be the extraction of a higher quantity of thermal energy from the storage zone, if the temperature achieved by the Solar Pond is higher then a known value, the injection of salt if the initial imposed profile is getting smooth, as a consequence of the diffusion process or of any convective instability, the injection of low concentration water on top of the gradient zone in the case of he existence of great losses by evaporation and the introduction of wind suppressors at surface, in the case of the existence of wind ripple at the surface [9].

If only the salt diffusion process was involved as a destabilizing process in a SGSP the expected lifetime of these devices without maintenance would be around ten years. However the above mentioned double diffusion instabilities and also the gradual decrease of transparency lead to the necessity of maintenance of the pond at least two times a year.

The idea behind this paper is to propose a different concept for the maintenance of a solar pond making maintenance operations simple standardized and with an annual periodicity.