Two pieces of prep work you should do before having concrete pumped around your new swimming pool
If a concrete contractor has agreed to use their concrete pumping machinery to create a concrete surround along the edges of your new swimming pool, you will need to do the following two types of prep work before they can start working.
Drain the swimming pool before you cover it
You will need to put a cover over the pool whilst the concrete pump is in use to prevent wet concrete from getting into the pool. If your swimming pool has been filled, then you might not want to drain it before covering it, simply because the process of emptying it and then refilling it would be a lot of hard work. However, you should resist the urge to skip the draining portion of this process.
The reason for this is as follows; if whilst the contractor is using their pump, a small part of the cover is pulled upward (by, for example, the wind) and some wet concrete gets into the water-filled pool, this concrete will probably cause a blockage in the pool filter when it is pulled into it during the filtration process. If this concrete hardens whilst the filter is being removed, it could be impossible to extract from this item's components, in which case you might have to buy a new filter. If this issue arises, you would have to wait until after you had ordered and installed this filter to start using your pool.
Conversely, if you drain the pool and some liquid concrete seeps under the cover, the worse that will happen is that this concrete will dry on the pool tiles. This is a minor issue that you could fix in minutes by gently scraping off this concrete with a semi-sharp tool.
Don't forget to protect the heat pump
If your pool is heated, then you must also prep the area near the pool where its heat pump is located to shield it from the liquid concrete that may soar in its direction when the contractor is using the concrete pump. If you don't and some concrete dries on the surface of the heat pump, it might obscure the pressure gauge or even solidify around the screws that secure the cover of the pump over its internal parts (which might make it impossible to remove this cover).
By putting some waterproof material (such as an old tent that you don't use anymore or a piece of tarp) over the heat pump and weighing this material down with bricks or rocks, you can keep it safe whilst the concrete is being pumped.