Posted: Tue Sep 10, 2019 9:09am
This is the product I mostly use, I haven't bought this particular one but they are fairly generic. These will last absolutely ages.
https://www.amazon.co.uk/Bluewater-Chlorine-Granules-5kg-Swimming/dp/B07RXKRJPL/ref=asc_df_B07RXKRJPL/?tag=cstareg-21&linkCode=df0&hvadid=265495279369&hvpos=1o5&hvnetw=g&hvrand=18101164524426535635&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9045040&hvtargid=pla-759274505956&psc=1
Initially I bought one of these starter kits which also has a foam remover - the foam remover can be useful if you use the tub a lot.
https://www.amazon.co.uk/Crystals-Cleaning-Multi-Function-Algaecide-Treatment/dp/B07B4FYD43/ref=sr_1_5?keywords=spa+chemical+kit&qid=1568098965&s=outdoors&sr=1-5&tag=cstareg-21
I normally change the water once a year though I did change it twice one year because the water had clouded due to us having too much sun creme on and or excessive use. That said the summer hasn't been that good weather wise in the UK this year so we haven't been in it that much. That damn jet stream :)
One of these allows removal of insects/ leaves unless really small - what sinks to the bottom gets vacuumed out with the wet and dry vacuum.
https://www.amazon.co.uk/Blu_Line-PLS01-Standard-Swimming-Skimmer/dp/B008TQVS9E/ref=sr_1_2?keywords=spa+cleaning+sieve&qid=1568099659&s=outdoors&sr=1-2&tag=cstareg-21
I've had my filter running continuously since last year - probably not good for it's longevity but I left it out over the last winter. It only really gets expensive when continually heating.
I've not really bothered cleaning my filters which are more expensive at around £12 a pop but they last for months.
Sorry that my product links are in the UK but as we haven't sold our house yet it is where we are, lol.