Yes it doesn't make sense to spend any more on Aquaguard, they are looters, when I wanted a dust bag for my vacuum they got another sales person along who was begging me to buy a air purifier. I no longer use the Eureka forbes vacuum cleaners because of the noise and pathetic build and more importantly the price they charge for filters, which does a poor job.
I have since replaced my vacuum cleaner with
this
There is no sensor in them, as long as you keep changing the first stage filter on a timely bases, the glass inside will be clear(mine is now 7 years running and the glass is still clear). You can see the UV light glowing through the white plastic water inlet connectors of the UV chamber, so you can know if its has become opaque.
The model I linked in the previous post has better plastics which is BPA free. Also when you have UF , the UV is more secondary. UV water needs to be consumed within a few hours, otherwise the virus will get reactivated, the amount of exposure time of water by domestic UV filters is inadequate to kill virus, it merely deactivates them for a few hours. UF on the other hand will block the virus.
In my UF purifier that I made, I am using a spiral wound BARC UF filter which has more life then the hollow fiber membrane based UF which needs a back flush to keep it from getting clogged. In a spiral would UF membrane I flush it every 2 to 3 days for a few minutes, so that I don't waste water. I could make it like RO which always outputs waste water but on the other floor, where I have installed it there is no drain located, hence I use a bucket any collect the water when ever I manually flush it.
Not sure what UF filter the model in that BPA free housing model, uses.