What about a box to hide power cables like this? It looks like it has clips to help keep the lid on and you can just screw it to the wall to hide the coiled wire.
You can also get brominating tablets (it’s a pool cleaning supply) with the same diameter as the official tablets and save a ton on the consumable aspect of that system.
Leisure Time 45425A Brominating Tablets, 1.5 Pounds https://www.amazon.com/dp/B000O5ZZ4W/ref=cm_sw_r_cp_api_glt_fabc_N4Z67HA4HD1M4HVS6KVE?_encoding=UTF8&psc=1