If the silicone between the bath/shower tray and the bottom of the tiles is leaking a black fluid, the wrong type of silicone has been used during installation.
Step 1: Use a silicone removal tool or work knife to remove all the silicone.
Step 2: Using nail varnish remover (or a similar solvent), wipe the area clean, trying to remove any discolouring left.
Step 3: Wait for the area to dry and check to see if the leaching continues. If it does, keep repeating steps 2 & 3 until the leaching stops.
Step 4: Apply Classi Neutral Cure 100% Silicone to reseal the area.
Note: When using nail varnish or any other chemical cleaners it’s important to read the health and safety information and follow all guidance and instructions.