From what I understand the EasyLife brand is not that common in the US, which means you will get limited responses. I myself have never seen the need for this specific product but use some of their other products such as Easy Carbo (excel equiv.). Some things to point out :
On their website here is the top lead sentence describing this product: "The ultimate water treatment that does not contain chemicals":eek5::eek5::eek5: . A product with such a description is an immediate no-buy for me. Some of their chemists should get in touch with Marketing Dept. and explain that even if it has only water or air in the bottle IT HAS CHEMICALS :icon_roll:
Besides this, it sounds like your normal "tap water conditioner" with added X substances and pipe-dream marketing. No need to put it outside the water changes and frankly I prefer to add simpler dechlorinators.
While we are on the topic, fish food adds the fertilizers (just at very low conc. ) and fish and microbial metabolism adds the CO2 ( just at very low conc. ). You see, there is no need to fear the chemicals. Most plants you have there have very low demands and not vacuuming the substrate helps. The plant selection is good and the environment created for the bettas also seems fitting. I would say you are not doing anything wrong.
If it works and you are satisfied with it keep at it and enjoy.