Hi drain and welcome to TFF!
I took a look at the "Acti" info and like the others, I can't quite figure out what it is. It is most likely either a "conditioner" (the term we commonly use for products that remove chlorine/chloramine and sometimes do a few extra functions) OR its a "bacteria in a bottle" product (another product range confusing for beginners because these are "hopeful" products (even in scientific circles), but are currently used "hopefully" in the "snake oil" sense on unsuspecting beginners, and in the final analysis, at least currently, are generally just very disappointing products per the reporting of our many members here on TFF.) OR, the "Acti" product is trying to be both of the previously mentioned type of products.
To my mind (unless there is a serious expense concern here), all of this is just a sideshow that is slowing you down from getting on with the lengthy process you are still going to need to go through before you have a biofilter capable of supporting fish and can get on with having fish and enjoying them.
Conditioners are, at the core, a pretty simple thing. There's a chemical that's cheap. It instantly deals with both chlorine and chloramine. Virtually all these manufacturers buy this chemical, put it in their variously colored and labled bottles, diluting it down by various amounts, and sell it at great profit in all the LFSs. For beginners, the info on conditioning can be a bit confusing if you search here on TFF because you will run across plenty of comments from experienced fishkeepers that they don't even bother to use conditioner! My advice is to keep in mind that there's a good chance that these fishkeepers are discussing what the do on large established fishtanks that have huge established biofilters and where they are often doing relatively smaller percentage water changes.
So for the beginner its probably prudent to follow the advice (offered by plenty of other experienced aquarists here) that they should get in the habit of using a good conditioner product, especially during the first six months or so, when their biofilter is still getting established. In fact its even recommended that one dose the conditioner at 1.5x or even 2x the recommended amount as given in the product instructions. My advice is not to go over a 2x double dosing though.
Now since the widely available chemical is so common and the process is so simple (since you just pour the right amount in to your tap water bucket or dose your tank for the amount the tank holds) there are many posts that just say more or less to get any conditioner and use it. For the most part this is true, but since we've got in to this discussion we might as well mention some detailed distinctions.
My own favorite conditioners to recommend to beginners are Seachem Prime and perhaps Amquel+, because they do a couple of things just right for the fishless cycling and the new fragile aquarium. Not only do they handle the chlorine or chloramine, they also are good at neutralizing any excess ammonia, making it safe for fish but still leaving it available as ammonium for the bacteria to eat and they are quite concentrated so that a bottle goes a long way.
Once one gets through the startup year or so, there are other conditioners that do interesting extra things that one might want to consider and ultimately, once one has very robust and established biofitlers, one might want to just consider getting a good pond conditioner so that the price is cut to the minimum.
As an example of the extra details, here, for instance is a nice little writeup by another person that I happened across just while looking up a product for this post:
Conditioner Article
Now that's not something I've used as a source before but you can see in the introductory paragraphs and some of the product descriptions, the same stuff I'm talking about up above. Anyway, for a small 5g aquarium, I'd get a small bottle of Prime and be done with it for a while!
Meanwhile, the other top priority things to be getting on with will be to search for a good testing kit, something like the API Freshwater Master Test Kit that most of us use. That's more or less essential to getting started in a good way and to help in your learning. And the search for the right kind of pure household ammonia that doesn't have dyes, fragrances or surfactants in it should get going too, as that can sometimes be difficult! All this and the reading too! Lots of homework!
~~waterdrop~~
/www.aquashop-mesure.fr/acti-clean-p...56277502ab2a0ab
